Entries Tagged 'Maintenance & Knowhow' ↓

Preamble
‘Knocking’ or ‘Pinging’ is a typical ‘rat-a-tat-tat’ kind of a metallic noise that a petrol engine lets out due to ‘pre-ignition’, when accelerated on load. Its ‘volume/loudness’ and ‘frequency’, amongst other things, depends upon the loading on the engine and its ‘rpm’. If allowed to persist, continuous knocking over a period of time can burn holes into its pistons and thus kill it completely.

The most common causes of knocking in a Petrol engine - and their preventive remedies - are in the following order:

1. ‘Lugging’ the engine in the wrong gear. i.e. shift one step down.
2. Over ‘Advanced’ Ignition timing - reset to OEM recommendation.
3. Adulterated/Fuel of lower than recommended ‘Octane’ Rating - go up one grade than what you have been using.
4. Fuel-Starvation, either due to a clogged Carb OR Fuel Injectors in an Mpfi Engine - get them cleaned up OR use well-branded Petrol Additives for the purpose.
5. ‘Anti-Knock Sensors’ not working in an Mpfi engine - for whatever reason - requiring professional intervention. Likewise, the Vacuum Advance/Retard feature in the Ignition Distributor being faulty in a Carb type engine.
6. Excessive ‘deposits’ within Cylinders AND Exhaust Line - mostly due to repeated short runs - more so in an Mpfi Engine coz it’s programmed to run in an ‘Auto-Choke’ mode when ‘Cold’.
7. Sticky Brakes. If so, the Car won’t roll freely even on the slightest of inclines when ‘let loose’.
8. A worn-out engine - will require a ‘compression check’ at an authorised Workshop to confirm.

‘In a relatively new car, say, with less than 50 kkm on its Odometer, (8) above will hardly ever apply and consequently, (3) and (6) are the most likely culprits. For the former, one can switch over to the new ‘Premium’ Petrol’s that are now available with an Octane rating of ~ 90 and if that doesn’t help, go for a non-stop 150+ km Highway drive every 3-months at speeds > 80 kph. This is recommended especially for those living in smaller/congested towns and doing short runs as a matter of routine.

By now, the new generation/premium/90-91 Octane petrol’s with additives pre-mixed are available practically all over the country and switching over to them should produce the desired difference. However, when doing so for the first time on a car with, say, more than 10 kkm on its Odo and more so if not having used ‘additives’ earlier on regularly, one should ensure the following:

1. Consume the existing fill upto ‘E’ level.
2. Fill to ‘F’ with the premium 90/91 Octane petrol.
3. ‘Top-up’ again by the time the level is down to 3/4
4. Repeat (3) above atleast twice - before reverting to one’s normal filling-up pattern.

This will ensure that the concentration of gums and glues that the premium petrol will dislodge from the system doesn’t go beyond the in-tank electric fuel pump’s handling capabilities. Otherwise, there’re good chances that they’ll kill the expensive fuel-pump.

Preamble
In Part-I of the above Article, we tried to understand how the ‘Cooling’ or the ‘Refrigerating’ part of the System works.

From April 2000 onwards, most Manufacturers have switched over to ‘R134A’ as the ‘Mandatory eco-friendly’ Refrigerant - as opposed to the earlier Ozone-depleting ‘R12′.

To an average Car Owner, it should suffice to bear in mind which System his Car has. This is clearly stated in his Owners Manual + suitable ’stickers’ in the Engine Compartment - such that while ‘topping-up’ no mistakes are made.

Suffice to say that ‘R12′ in a ‘R134A’ System can be tolerated to some extent but the other way round is a no-no. This is because the ‘latent heat of evaporation’ of R134A is ‘lower’ than R12 and therefore, R134A systems call for larger front-end Condensers and in-cabin ‘Cooling-Coils’.

To make things a little more complicated, most of the present generation Cars nowadays come OE with an ‘HVAC’ - Heating Ventilation and Air Conditioning - System. The major advantage of such a System is that it allows one to choose the most comfortable in-cabin Temperature without having to suffer the suffocating thermostatic ‘dead-band’ of an ‘AC System Only’ in the earlier Cars.

Now let’s see how this is achieved and what are its plus/minus points - as far as load on the engine and hence the fuel consumption is concerned.

A Typical HVAC FAQ
People often wonder or wish to know if there is going to be a difference in Load on the engine/fuel consumption when one keeps the ‘Red to Blue’ Thermostat at max blue or less. For example, what happens when one moves the Thermostat from the coldest to an intermediate position - Does the AC Compressor run continuously or keeps cutting in and out - loading the Engine accordingly

OR

Does it run continuously and thus load on engine more?

One would ask such a question when failing to notice any difference on the Load on the engine when the AC thermostat is set to less than ‘max-cool’.

Or in other words, the AC Comp doesn’t seem to cutout even when one desired less than max cooling from it. So - where does the extra cooling go when the Thermostat is set to low!

Fundamentals of ‘HVAC’ Systems
1) The Cooling Coil of the A/C has a Thermostat of a ‘fixed’ setting of (+) 2-4*C, to prevent its ‘frosting’. In the mpfi Cars, it’s an Electronic ‘Thermistor’ type. Therefore, in the ‘max cool’ setting, it cuts off the Comp whenever the Cooling Coil approaches frosting, depending upon the ‘heat load’ on the System.

2) In the earlier A/C cars like the M800 which didn’t have a Heater also, the Thermostat used to cut off the Comp, resulting in a ‘dead band’ of about 2*C before it could cut-in again. During this dead band, like in Room A/Cs, there comes in a feeling of suffocation.

3) Therefore in the present generation Cars with HVACs, instead of cutting off the AC Comp altogether and thus get that suffocating feeling, there is a ‘progressive inflow’ of Hot air let in from the Car Heater and mixing it with the Cold air from the A/C Cooling Coil, as you slide the so called the ‘Thermostat’ to ‘less cool’ positions.

A simple diagram below illustrates how this is achieved -

4) Consequently, depending upon the in-cabin thermostat setting below ‘max-cool’, the AC Comp is on most of the time. And whenever the Comp (fixed displacement type) is on, it will lead to the same ‘drag’ on the Engine.

5) However, with the advancement of Technology, fixed displacement type AC Comps are increasingly getting replaced by ‘variable displacement types’ on the more expensive Cars (Cielo was the first one to have it), which are able to ‘adjust’ their ‘output’ depending upon the total ’system requirements’. Consequently, this results in lower drag on the Engine even when the Comp is on, depending upon the Heat Load demand on it.

To sum-up, particularly in the present “B” gr Cars’ HVAC Systems having ‘fixed-displacement’ type AC Comps, it’s advisable to keep the in-cabin Thermostat on ‘max cool’ setting and bear some of the suffocating feeling if one wishes to get the best possible FE with A/C on - rather than to let the AC Comp run all the time by selecting a lower setting.

However, during certain times of the year when the Summer is just setting in or exiting - coupled with the Windscreens’ ‘defrosting’ needs depending on the atmospheric humidity at the same time - it may become inevitable to select an intermediate setting for the best/most comfortable results. In such a situation, the HVAC System would decide for itself as to how much the AC Comp has to work. Afterall, life is meant to be enjoyed and not spent in counting pennies all the time!

And before concluding Parts-1 and 2 of these Articles, some FAQs:

Q1) What is the best way of putting on the A/C when the car cabin is hot (i.e when the car is under the sun for a long time)? I have heard people say that the windows should be down for sometime with the A/C on? Is this correct? Should the A/C be on or is it just the blower that should be on?

A1) Most Owners Handbooks cover this aspect. The idea is to keep the heat load on the Car AC system as low as possible to begin with for ‘perceived’ faster cooling - by driving out the ‘trapped’ hot air which can at times be + 20 to 30*C above the ambient temps ! I have personally ‘clocked’ +60*C inside in N/I peak Summers with +40*C ambient !!

The best way to do it is to atleast roll down the 2-front windows, switch on the blower only to max/fresh air mode and drive off for ~ 2-3 mins. Thereafter, roll up the windows, turn the FAD to ‘recirc’ and sw on the Comp - leaving the blower to max - to be progressively lowered to comfortable speeds - usually 1 or 2 after a while.

Q2) I know of people who put the A/C off and on at intermittent intervals to save on fuel when the car is running/at signals. Is this a good practice?

A2) It’s out of ignorance. The more you manually sw on/off the Comp - the more you’re cutting into its Clutch life. Above all, why sweat at the traffic lights. AC is meant to keep you cool and not sweat. If you choose to have it, use it ! If it has to cut-off per System needs, it’d do on its own!!

Preamble
It’s that time of the year when Car AC’s are just about being switched in - even in North India. They perhaps never got switched off ‘down south’ of Nagpur!

Considering the fact that most motorists face problems with their Car ACs sooner than later, it’s worthwhile to get the hang of it all - coz ignorance in such matters can cost one dear - in more ways than one.

The System
All Car A/C Systems are basically similar, with a cooling capacity of almost 1-1.5 tons (!), in the sense that they essentially comprise:

1. An Engine Driven ‘Compressor’ with an ‘Electro-magnetic’ Clutch. The Compressor Capacity is designated in ‘CCs’, like the Engine. 80 to 120 CCs being the most popular ratings for passenger Cars of the types on our roads. The ‘Refrigerant’ used so far was ‘R-12′ of the ‘CFC’ family of gases but is now progressively replaced by ‘R-134A’, a NON-CFC, for environmental considerations.

2. A Grill-front mounted ‘Condenser’, cooled either by a common (Radiator) fan or a ‘Dedicated’ fan of its own. For example Maruti 800 and Zen/Esteem - respectively. The latter is a superior and hence a more efficient but naturally a more expensive system.

3. This is followed by a ‘Receiver-Drier’, mounted somewhere in the Engine Compartment. Its purpose is to control and ‘Purify’ flow of the Refrigerant to the cooling coil, under various operating conditions.

4. A ‘Cooling Coil’ with a multi-speed Blower mounted in the Passenger Compartment, generally inside the Dashboard. This unit has two additional and vital parts viz. (a) An ‘Expansion Valve’ and (b) a ‘Thermostat’. The latter can be a ‘Bellows’ type like in the pre/EU-I M-800s or ‘Electronic’, as in the Zen/Esteem and some others. All Mpfi Cars today have the Electronic one only. Larger vehicles like the Tata Safari have two such units, one up front and the other at the rear, to cool the entire passenger area effectively.

5. The ‘Expansion Valve’ regulates the quantity of gas flow to the Cooling Coil (also called the ‘Evaporator’), depending upon the ‘Heat Load’ on it and the ‘Thermostat’ prevents ice formation on the cooling coil, which not only affects the cooling efficiency but if allowed to happen, can also damage the system.

How to get the best out of your Car A/C.
Let us consider the M-800 System, being most omni-present and ‘Edgy’ by design, by virtue of the Engine itself being < 50 Bhp. This exercise can be divided into two parts:

A. Your Garage.

(i) It should check whether the System is Healthy, by way of Suction/Discharge Pressures, Internal or External Component Blockages, ‘Pressure equalisation’ times on Switching Off and Cabin Grill Temperature.

(ii) On M800 ‘Retrofits’, check whether a 120Watts Radiator Fan is provided, by replacing the ‘Standard’ 80-Watt one.

(iii) Ensure proper Foam sealing on all the four sides between the Radiator and the Condenser, between the Exhaust Manifold and the Condenser (behind the Bumper). This is the most neglected area.

(iv) Existence of a ‘Heat Shield’ around the Compressor discharge pipe and the Condenser in an M800, as provided in an ‘OE’ fitment. This again is generally thrown away by mechanics right during the first service of a new car, thinking that it serves no useful purpose. If it were so, it won’t be provided by the Manufacturer in the first place and be subsequently priced as an MGP/SGP Spare costing over Rs: 350/-!

(v) Whether the Radiator Fan comes on and stays on even when the Radiator Thermo Switch cuts in. Approach in reverse sequence especially for the Retrofits.

(vi) Check all parameters of the Engine Tune, such as Idle RPM/CO, FICD RPM (1050), Ignition Timing including satisfactory working of Centrifugal and Vacuum Advance features, Dwell angle and its stability up to 4000RPM, Spark Plug condition and Gap, Air Cleaner/Petrol Filter Cleanliness, Carburetor II Butterfly in good working order, Engine Valve Clearances and Timing (if suspect).

(vii) Wheel alignment, Engine Compression/Power balance (if suspect), Radiator/Condenser Cleanliness (inside/out), condition of Radiator Cap/Thermo valve (Change if suspect). In our Dusty conditions, these two have to be pressure washed every 2-months from both sides.

(viii) Correctness of Dash Board Temp Gauge vis-a-vis digital thermometer in the Radiator neck, Radiator Fan coming on without A/C around 85*C to 90*C, full closing of Fresh Air Damper in ‘Recirc’ mode and proper alignment in ‘Full Forward’ Mode.

B. Yourself

(i) Do read and follow the Owner’s Manual on the Car A/C usage.

(ii) Maintain the recommended Tyre pressures.

(iii) Always drive in a gear one step lower with A/C on, than what is recommended for normal driving.

(iv) Ensure that the ‘Recirc’ flap is always closed and avoid driving in our dusty conditions with Fresh Air flap open, as it deposits dirt on the cooling coil, thus making it less and less efficient.

(v) Always get your A/C checked out at a competent and reliable Garage at the beginning of a season.

(vi) Check frequently the ‘free-rolling’ of your car, to guard against ’sticky brakes’. This can be very easily done when coming to a stop, say at traffic lights. Just let go of the brakes when the car is about to stop and shift to neutral. The car should continue to move forward without any noticeable feeling of a ‘drag’. Don’t forget to engage the hand brake when you come to a stop!

(vii) Last but not the least, it’s of utmost importance to switch on a Car AC atleast once a week even in Winter times and let it cut-off on its Thermostat once or twice - to keep the System internals well lubricated. This is coz the lube oil of an AC System moves along with the AC Gas !

C. What can go wrong!
Perhaps the most common ‘complaint’ of most Car Owners is that either the AC is not cooling well enough OR when they use it, the engine over-heats.

Here are some tips to equip you against being taken for a ride by who so ever you choose to have it fixed by:

i) Not Cooling enough :

The main reasons for this, assuming that your System is physically in good shape, can be - a) Under OR over Gas Charge, b) Dirt-clogged front-end AC Condenser, c) Choked ‘Receiver-Drier’, d) Faulty ‘Expansion-Valve’, e) A dirt-clogged ‘Cooling-Coil’, f) Faulty ‘Anti-Frost’ Thermostat on the Cooling Coil, g) Loose AC Compressor Drive Belt OR its faulty ‘Clutch’.

ii) Engine Over-heating :

Likewise - a) Dirt-Clogged Engine-Radiator, b) Engine ‘Out of Tune’, c) Jammed II-Butterfly - especially in Carb type M800’s, d) Driving in a gear higher than what the engine demands, e) ‘FICD’ engine speed being much higher than recommended, f) Car not ‘free rolling’ enough for whatever reason - as covered above.

Conclusion
Once you have got the hang of it as to what makes it tick and keeps it ticking, there is no reason why it should not deliver satisfactory performance even through the peak of our North Indian summer. I have personally driven an M800 through Rajasthan in the month of May with outside temperature being 48*C, Cruising speeds up to 100kph, Cabin Temp. around 25*C, and the Engine Temp. not crossing the halfway mark!

Forewords:
With the summers having already set-in, it’s time to check one’s Car AC System, to ensure that it performs well when needed most. Just remember that a Car AC in principle is quite like the ‘Split-AC’s that have now become popular for home/office use - except the fact that the ‘outdoor unit’ is housed in the car’s engine compartment and the ‘cooling unit’ inside the cabin, in the dashboard.

With the M800 still being the highest in numbers on the roads and most people being some what penny-wise pound-foolish, a lot of them buy a ’standard’ M800 and then try to retro-fit an AC ‘Kit’ as cheaply as possible. Naturally, they don’t deliver what they promise and the Kit Fitters wash off their hands by finding faults in the car/engine. So here’s what you can keep in mind while going in for an AC-Retrofit on an M800…

There are ONLY 2-AC ‘Kits’ suitable for an M800 - one is the Subros’ that comes as an OE fitment and the other is the after market ‘Sanden’. The rest/cheaper wayside ones are mostly ‘mix n (mis) match’ and as such, they seldom work satisfactorily, if not kill the engine sooner than later by overloading it. Besides, all car AC’s can rob a car of 10-20% of its power and associated fuel consumption - for obvious reasons.

On the other hand, while it cools better than the Subros’, due to it’s larger compressor and condenser/cooling coils to match, the drawbacks of a Sanden Kit for the M800 are - i) Compressor overloads the engine more than Subro’s, ii) if its front end Condenser is ’skived’ type, it is unsuitable for the dusty Indian climate.

As such, there’s no Kit better suited for an M800 than the OE/Subro’s and that too installed either by a competent MASS or a Subro’s Authorised Service Station. Such a Kit including the 120-Watts Radiator Fan upgrade costs around Rs: 18k lot. Make sure that the price quoted to you for it includes the replacement 120-Watts Radiator Fan, which is a must for both Sanden as well as Subros.

However, it must be kept in mind that Cars older than, say, 3-yrs and specially the ones having Aluminium Radiators are most likely to suffer from overheating after a Retro-fit even entirely as recommended above - due to the inevitable scale formations within the Engine/Radiator.

Should that happen, then it’ll call for a ‘Cooling System Flush/de-scaling’ - using one of the many well-branded products available in the market - exactly as per instructions given on their packaging.

However, having decided to go in for either of the two, M800 being under-powered as it is, to get the best results including on the life of the engine, one must ensure that - i) with AC on, always drive in one gear lower than what one would other wise do w/o AC i.e. in 3rd at speeds below 40 kph, in 2nd below 20 and so on, ii) get the std 80 watts radiator fan replaced by a 120 watts ‘Denso’ one. This is reqd even with Subro’s kit as otherwise your engine is bound to overheat in city traffic and damage itself in summers. The outgoing fan has hardly any resale value so you may as well keep it as a contingency spare and iii) if the condenser fins are ’skived’ type, make sure that you have them medium pressure washed atleast once a month and less frequently if they’re of ’serpentine’ type. Further, this must be done even in winter times when the AC is not in use and ALL car AC’s as such should be switched on atleast once a week for 15-20 minutes in winters also, to keep their Compressors well-lubricated and thus in good shape to face the next summer.

Forewords
Having got an over-view of a car’s basic electrical system last week, here’re some Do’s and Dont’s to keep them trouble free:

Do’s

• Keep a regular check on the electrolyte level in your battery. Top-up to ‘max’ level, as and when required, using ONLY pure/battery grade distilled water. Overfilling is to be avoided at all costs as the electrolyte/acid will spill over when the battery is getting charged and thus ruin its adjoining areas for good.
• Even the present day ‘maintenance free’ batteries require such attention ~ every 3-6 months and the ‘semi-sealed’ ones once a year or so. Keep its terminals free of sulphate’ deposits and lightly smeared with petroleum jelly.
• Likewise, it’s important to keep an eye on the Alternator drive belt tension since belts tend to loosen with age/mileage. A loose belt can lead to a flat battery after a while, for no fault of the Alternator.
• Switch-off headlamps at night in b2b traffic but leave the parking/tail lights on – wherever possible.
• This way, an OE Alternator can last ~ 50 kkm+ and well branded Batteries ~ 3-yrs before needing any service/attention. As and when needed, entrust the work ONLY to their Authorised Service Centres.

Dont’s

• On the present MPFi/CRDi cars, it’s NOT advisable to retro-fit any electrical accessories, such as music systems, fog/rally lamps, high wattage head lamps, remote/central locking, fancy lights/horns etc that are not ‘OE/Dealer Approved’. If at all, that too only by the Dealer and against a formal receipt. Otherwise, your OE Warranty and consequently the Insurance Cover stands to be annulled for having carried out ‘unauthorised’ modifications – not to mention utter loss of reliability of the vehicle.
• It’s commonly advised out of ignorance even in prominent Media that using ‘relays’ for retrofitting high wattage accessories will solve the problem. Nothing could be farther from truth as – a) this’d inevitably involve tampering with the OE Wiring Harness that’s a taboo for MPFi/CRDi’s and b) a relay is just a ‘passive’ switching device that can only increase the load switching ‘capability’ of the OE switches and therefore, the additional electrical load in terms of Amps/Watts has to come from the Battery and in turn the Alternator only.
• The present day cost-competitive ‘edge’ designs leave hardly any room for such overloading, including the OE wiring. In plain speak, it’s asking for trouble – relays or no relays.
• Some vitals of a car such as the Starter, Horns, Brake Tail Light Bulbs, are NOT ‘continuously’ rated - like a household Mixie - as their application doesn’t warrant so. Therefore, cranking a Starter repeatedly for more than 3-4 secs at a stretch can considerably shorten its life, along with that of the Battery. Ditto for Horns. They should be ‘tooted’ only in short bursts. Likewise, don’t rest your foot on the brake pedal when parked or waiting at traffic lights. Instead, shift to neutral and engage the parking brake fully BUT don’t forget to release it when taking off!

Forewords
Development of a rechargeable Battery in the ‘20s revolutionised the Electrical System of a Car thereafter. Today, particularly in the luxury sedans’ of the west, they can be as complex as in a long-haul passenger jet airliner – deploying some kilometers of specialised wiring, relays and switches.

Electrical problems like a flat battery or malfunction of the key parts are most frequent that plague an average motorist. So sooner one understands the basics, the better for him and his vehicle. Due to space constraints, this one is split into 2-parts – Part 1 covering the basics and Part 2 some Do’s and Don’ts.

Some Basics
The ONLY source of ‘power’ in a conventional vehicle is its engine. Therefore, its Alternator and in turn the Battery are ‘secondary’ sources, ‘powered’ by the engine. Today, all cars have 12V DC Systems whereas heavy commercial vehicles deploy 24V DC for understandable reasons.

Flow of electricity in a circuit is like flow of water in a stream, where ‘velocity’ of stream (kph) is equivalent to system ‘voltage’ (V) and rate of flow (cusecs) is eqvt to current in ‘Amperes’ (A). Further, an electrical ‘load’ is measured in ‘Watts’ (W) and in a DC system, it’s a product of VxA.

Battery
The fundamental requirement of a car battery is to provide reliable power to its ‘starter-motor’ and its Ignition System, to fire the engine even under most adverse conditions – such as sub zero temperatures, prolonged shut downs, poor state of engine health etc.

Therefore, a car battery is ‘sized’ accordingly i.e. higher the power required to ‘crank’ the engine, ‘larger’ (AH) the Battery. Typically, a battery type ‘NS40S’ has an AH capacity of 30@20 hrs. In other words, such a fully charged battery can deliver 1.5 Amps for 20-hrs.

It’s note worthy that ‘A’ and ‘H’ are not always inversely proportional i.e. if such a battery is discharged @ 5 Amps, it’ll last < 6 hrs!

Alternator
Having got a suitable Battery on-board, it’s logical that it’d need to be kept fully charged, as it gets substantially discharged every time the engine is cranked. Until mid-‘60s, this job was done by a ‘dynamo’ but as load demands increased, it was found wanting in more ways than one – such as inability to charge at low/idling engine speeds and relatively short/unreliable life due to the ‘commutator’ it had to have, to convert the basic ‘AC’ it generated into ‘DC’ for use on board - coz the Batteries are DC only.

This need paved way to development of ‘Alternators’ that overcome such deficiencies, where wear-prone ‘commutator’ got replaced with a solid-state ‘Rectifier Plate’ and its external electro-mechanical ‘Voltage Regulator/Cut-out’ got replaced with in-built (solid state) voltage regulator – to maintain the Alternator output within 12-15 Volts regardless of the engine RPM.

Today’s average sedans have Alternators with an output capacity of ~ 60 Amps/15 Volts a/a 20 Amps of Dynamo’s of yore and are so designed that they’re able to meet practically all the ‘designed’ electrical loads of a car while on the move, including while idling at traffic lights, and yet have required spare capacity to keep the battery fully charged at all times

Preamble
Last week we read about odours in a car. Since it’s a piece of complex machinery in motion, some noises are inevitable even though today’s cars are a lot quieter than their decade old siblings. Some of these are normal where as some are like coming events…

Unfortunately, an average owner-driver is unable to distinguish between the two. So let’s try and explore these.

1. Normal Noises
To qualify these, let’s take the noises a new car makes when you first drive it as ‘normal’ - assuming it didn’t have any defects. These can be broadly subdivided as relating to - i) Engine/Transmission, ii) Suspension, iii) Under chassis and iv) Body/doors/panels.

First types will be lowest when the car is stationary with engine idling. Such ones will progressively go up depending upon - a) engine rpm and b) road speed. In the former category, ‘refinement’ of the engine/transmission design and ‘build-quality’ holds the key whereas in latter, ‘rolling noises’ depending on tyre/tread pattern vis-a-vis road surface AND the front/rear Suspension Design gain prominence.

2. Abnormal Noises
Keeping in mind that ‘all aluminium’ engines are noisier than cast iron block types, it’s interesting to note that all the refinement of engine/transmission design can go for a six if the rolling noises predominate at higher speeds, in some makes from as low as 20 kph upwards. To a large extent, narrow footprint tyres preferred by OEMs due to better fuel efficiency are mainly responsible for such rolling noises, closely followed by faulty suspension design that leads to ’structural resonances’.

On the engine/transmission related noises, even in a healthy engine excessive ‘valve/tappet clearances’ can add significantly to the noises it’d make. In addition, faulty foundations of engine/gearbox too can add to them. Besides, ‘peripherals’ like drive belts, water pump, AC comp., power-steering pump and alternator bearings too can get noisy, with impending failure. It should be kept in mind that any engine/gearbox/accessories will get noisier as they get older/wear out.

Over and above, the most common noises in Front Wheel Drive Cars are from wornout ‘axles’. Every FWD car has two of them and each has two very hi-tech ‘Constant Velocity Joints’ at its either end, covered with Synthetic Rubber Boots and packed with special ‘Moly’ grease within. Normal life of such CVJ’s in our conditions is ~ 60,000 kms PROVIDED their SRB’s don’t suffer any premature failures as is quite common on our grit-laden roads, especially during the rainy season. Once that happens, the special grease escapes from the CVJ/SRB’s and dirt gets in - leading to the CVJ getting damaged in no time.

The rattling noises a wornout CVJ makes are quite characteristic and as a thumb rule, the lhs ones are the first to give way for understandable reasons. If an Axle rattles while turning, even on take off from standstill, it’s the ‘wheel-end’ CVJ that’s gone. On the otherhand, if such rattles are heard on accln. or de-accln., then it’s the ‘drive-end’ CVJ that’s wornout.

In such situations, it’s wise to replace the entire Axle assy with an OE part for lasting relief, though expensive, as regardless of what one may advise it’s next to impossible to satisfactorily re-furbish such hi-tech CVJ’s in the after market.

3. Suspension Noises
These can be broadly classified as - i) Soft ‘thuds’ and ii) Rattles. When the soft thuds become louder and occur without much provocation, as going over small potholes, one’s Shock Absorbers will need looking into. If there are ’squeaks’ emanating from under-sides, it’d be various Suspension Rubber Bushes that’d need attention. Normal life expectancy of such parts on our kind of roads is ~ 50,000 kms and that too if the car is driven carefully.

Rattles, on the other hand, signify some things loose or mis-aligned with car’s under-sides. Most common culprit is the exhaust line that’s either damaged due to a hit or unsatisfactory repairs done while replacing a muffler etc.

4. Steering Noises
While some ’soft ones’ are inevitable especially on our kind of roads due to the inherent ‘multi-link’ nature of such mechanisms, when they get louder and manifest without much provocation that one needs to attend to them.

Such noises can arise either from loose or wornout - i) ‘ball-joints’, ii) ‘rack and pinion’ assy incl its 2xguide bushes, iii) unbalanced front wheels and iv) steering column bearings/bushes and/or its ‘universal joints’.

Logically, these should wear out time/distance wise in the same sequence as above but lapses in their manufacturing quality or assembly can create exceptions. Above all, fair amount of skill is needed in identifying the real culprits coz every thing out there is so ‘inter-connected’.

5. Doors and Windows
Such noises are perhaps easiest to locate for a layperson and can afflict even a new car. From doors, they’re due to their mis-alignment with the body frame or excessive slack in their locks/latches. Ill-secured door panels too can vibrate and make noises. On other hand, window glasses tends to ‘chatter’ if not fully raised or lowered - unless their guide ‘channels’ are wornout due to age - usually beyond 3-years.

Also read:
How do I keep my car trouble-free
Smells in a car

Preamble
Now that we have had a look at how to keep our cars trouble free. Well, here’s some more - keeping in mind that cars are somewhat like other living beings and let off distress signals when all is not well with them. So as an intelligent owner/driver, it’s worthwhile to detect them in good time before it’s too late - be it as a driver or as a passenger.

1. Fuel Odours:
Such smells can be most dangerous of them all - implying a potential fire hazard. These arise due to either a perceptible leak or ’sweating’ in the ‘plumbing’ between the fuel tank and the engine. A competent Garage or a DIY owner can spot them by inspecting the fuel lines to and from engine to fuel tank and take remedial measures.

However, in some of the present day cars, in-cabin fuel odours are often noticed even when the above plumbing shows no flaws. These have been traced to a faulty gasket on the fuel tank flange for accessing the fuel pump/level gauge under the rear seat! In the older non-Mpfi cars, in addition, these could also arise due to ‘over-filling’ the fuel tank.

2. Burning Odours:
Present day cars deploy a variety of synthetics and plastics within and outside their cabins. A ‘normal’ person can distinguish amongst these as those arising out of - a) Friction materials used on Brake Linings/Clutch Plates, b) Rubber or Plastic Parts and c) Lube Oils or other engine fluids.

The friction material odours can arise due to ’sticky’ brakes or more commonly, the Parking Brake not having been released fully. A Clutch too can give out burning smells if ‘rode on’ in heavy (b2b) traffic or uphill.

For rubber type odours, under inflated tyres are the most common culprits and plastic types prima-facie mean overheated electrical wiring either within or outside the cabin. Most common cause for such ones is the deployment of ‘unauthorised’ and crudely installed electrical accessories such as a high-powered Music System or a Remote/Central Locking System.

In addition, if the roof lamp is left on for long times, its plastic cover can over heat and emit such odours. Tampering with OE wiring harness is an absolute taboo with the present Mpfi Cars.

On the other hand, Oil/other fluids’ burning type odours invariably imply either an overheated engine or oil leaks from the engine/gear box coming into contact with exhaust line that can run as hot as 500.C+ next to the engine - tapering off to nearly 100.C towards the tail end. This too can be a fire hazard. Brake Fluid leaks within the wheel assemblies can also emit burning smells, as brake discs/drums can get very hot under hard braking.

3. In-cabin Odours:
The last of in-cabin odours can be ‘organic’ type - let off by decaying matter within. Most common ones are from the Car AC, due to rotting matter deposited on its Cooling Coil. Since such matter can gain access via the fresh air duct if kept open and in our conditions, it’s advisable to keep it shut most times. The only remedy here is to have the AC/Cooling Coil Serviced, which can be a time consuming and expensive. As in most cases, prevention is better than cure.

Other major offenders in this class are debris of eatables accumulating in the inaccessible corners. The best thing to do is to avoid any eatables inside the car especially with children and if inevitable, have the car internals first vacuumed thoroughly and only then have the various nooks and corners blasted out with compressed air - only to be vacuumed again. If ‘pre-vacuum’ were omitted, most of the dust so dislodged would settle down on the AC Cooling Coil - with its own undesirable consequences.

Having ensured all these, it’s a good idea to keep a car ‘air freshener’ inside but mind you, let it not be like spraying perfume to suppress bad body odours!

Also read:
How do I keep my car trouble-free
Noises in a car

Preamble
Besides noises, in any car some ‘vibrations’ are inevitable. These are ‘noises’ that can be ‘felt’ but not heard. It can be difficult for an average person to distinguish between normal or abnormal vibrations. So let’s try and explore them…

Causes of Vibrations
It’s elementary physics that any rotating mass will vibrate if its weight is not evenly distributed around its ‘axis of rotation’. Their ‘intensity’ is proportional to such ‘unbalance’ AND speed of rotation. If vibrations are not contained to ‘safe’ levels, ‘metal-fatigue’ sets in a machine, eventually leading to its wreckage.

Prime source of vibrations in a car is its engine – followed by wheels and road undulations transmitted to its body by its suspension. Let’s look at each of them.

Engine
The ‘reciprocating’ movement of pistons in an engine is converted to a ‘rotary’ one by its ‘Crankshaft’, which is linked to them by ‘Connecting Rods’. Therefore, unless each one of these parts is individually well balanced, it will vibrate.

Despite, some vibrations are inevitable. These are ‘damped-out’ by flexible ‘foundations’ between the engine/gearbox and the car body. Such foundations are made of rubber fused on metal anchors but in more expensive cars, ‘hydraulic’ foundations have become a norm.

However, even a well designed engine can vibrate if – i) its ‘idling speed’ is below normal, ii) it’s over loaded due to improper gear selection, iii) its foundations are damaged or misaligned, and iv) if one or more of its cylinders is not producing right amount of power compared to others.

Wheels
Until the advent of Maruti-800 in mid ‘80s, concept of ‘wheel balancing’ was unknown in India. A wheel being an ‘assembly’ of its rim, tyre/tube, is invariably unbalanced even when brand new, because of permissible manufacturing ‘tolerances’ of its constituents.

And when the wheel diameters get smaller, their ‘rpm’ for a given road speed goes up compared to larger ones. Given the overall ‘lightness’ of cars nowadays, such unbalance in wheels produces unwanted vibrations in an otherwise ‘smooth’ car. Worse still, it makes the steering ‘wobble’ at higher speeds.

It’s worthwhile remembering that a wheel once ‘balanced’ won’t stay so for long because of daily/uneven wear going on its tyres due to braking/cornering etc. Worse still, the ‘balancing weights’ can and do fall off for many reasons. So it’s advisable to get one’s wheels re-balanced, say, every 5,000 kms.

It’s a popular misconception that only front wheels need re-balancing because that immediately reflects as steering wobble. Since any unbalance in rear wheels also produces vibrations and these, even if not felt as such, do eat into the lives of rear suspension bushes, shock-absorbers AND wheel bearings.

Like wise for Stepney – for simple reason that one may need it any time upfront and if it’s unbalanced, one’ll have a wobbly steering till re-balanced. From this point of view, it makes a lot of sense to have a wheel re-balanced immediately after puncture repairs before stowing away as spare.

A finer nuance to have all the 5-wheels in good balance all the time is that if they’re not, the front ones will inevitably wobble a bit even if not perceptible. Consequently, car’s ‘rolling’ resistance and hence fuel consumption stand to go up!

Conclusion
From the foregoing, it can be visualised that a well tuned engine and all the five wheels in good balance can add significantly to the overall life of a car.

I’m often asked this question and I tell them that every Car Maker provides a ‘Preventive Maintenance Program’ in its ‘Owners Handbook’ that comes with it - which lays down a detailed recommendation on time-bound as well as distance-bound basis. Execution of these in toto at a competent and well- equipped Authorised Workshop is your best insurance towards its reliability.

Next comes ‘how to get maximum mileage out of it’. Well, the logic is simple i.e. by ensuring that all the above ‘PMPs’ are done well and in time. In addition -

1. Maintain correct Tyre Pressures by checking/resetting once a week when ‘cold’, using a reliable Gauge,
2. Ensure correct Wheel Alignment by checking once every 10,000 kms,
3. Restore ‘Dynamic Wheel Balance’ of all the 4-Road Wheels every 5,000 kms if not earlier on ‘SOS’ basis - such as after a puncture repair,
4. Avoid short runs to the extent possible, and above all
5. Drive sensibly and in correct gear all the time - without any ‘Jack-Rabbit’ starts and stops.

Quite often, overly cost conscious owners mislead further by their ignorant road-side mechanics act penny-wise-pound-foolish, by questioning the very basics of present day car designs. For example ‘what purpose does ‘Coolant’ Serve and is it necessary to use it’! I must confess that I’m at a loss at such ones, though I try and recover my composure as quickly as possible.

The logic here is that the present generation Car Engines are high performance ‘precision machines’ with complex and narrow Coolant Circulation Passages within. Use of a good quality Coolant ensures they stay ‘corrosion and scale-free’ for a long time and lubricate the Water-pump internals as well. If not, you can rest assured that your car will start overheating at the slightest provocation. For best results, only distilled water should be used to dilute the ‘coolant-Concentrate’ to the recommended level. Coolants, like Gearbox Oils, have a life too and should be regularly replaced as recommended in your car’s ‘PMP’.

hen there are some other features of present day cars that baffle not only their first time owners but their friendly road-side mechanics also - such as “my Car heats-up very fast and runs much hotter than my earlier Cars of the ’70s. My Mechanic tells me to remove the ‘thermostat valve’ from the Cooling System”.

Nothing could be farther from truth and asking for trouble. The present generation Cars are ‘designed’ to run between 85-95*C for maximum fuel-efficiency and reducing exhaust pollutants to a minimum when the engine is below its designed operating temperature. The purpose of the Thermostat Valve is to ensure that these two requirements are met silently and that too regardless of the Ambient Temperature outside.

Then there are some others, such as ‘when should I use the 5th-Gear’. The answer is that 5th gear is a ‘cruise gear’ and in most cars, depending on their ‘cc’, one can comfortably get into it at speeds ~ 50 kph. It relaxes the engine by ~ 20% and affects the fuel consumption (and pick-up) accordingly. However, there’s no point in getting into the 5th gear unless one can sustain it for atleast a km or two. Otherwise, one will be shifting 5th and 4th/3rd all the time. This will waste more fuel than saving and prematurely wear off the Clutch and the Gearbox also at the same time.

Last but not the least, in these days of driving in the ‘fast-lane’ when people have no time even for a breakfast before dashing off to work, most tend to forget some basic daily checks on a car that hardly take a minute but can save hours by the road side in case of an avoidable breakdown. Here’s what one should do as a habit -

1. look at all the 4-tyres to see they appear properly inflated,
2. if one can see the car’s undersides while approaching from a distance, see if it has dropped any significant oil or other fluids overnight. If not, then after moving it off but before taking off for good,
3. smell for any petrol or oil odours inside before starting the engine,
4. after starting, wait for atleast 10-secs for it to fully ’stabilise’ electrically as well as mechanically before vrooming off. Look out for any unusual noises/vibrations during this time and
5. ensure all lights incl cabin are switched off while parking during the day and at night for good. Otherwise, be prepared for a flat battery to greet you when you try to start it the next time!

Also read:
Smells in a car
Noises in a car