A Cold-stalling Engine – Causes and Cures Part 1

Preamble
With the winter setting-in across most parts of the Country and Pre/EU-II kind of M800s and other Carbureted/Mechanical Distributor Type Cars like the Zen’s and Esteem’s still being there in appreciable numbers, I feel it’s time to draw Car Owners’ attention to the topic under discussion.

Most non-MPFi Car Owners experience that when they start the car in the morning or after it has been shut down for 5-6 hours, it feels very sluggish. Engaging the car in 1st gear and upon even stepping on the gas pedal, the car does not ‘speed up’.

This goes on for a while and only after the Temp. Gauge needle crosses the ‘C’ and goes beyond, the car feels ‘normal’. All this despite the Engine Tune being in good order.

The answer to this is that a ‘cold’ Engine is inherently sluggish, to prevent it from spewing out excessive pollutants during its warm-up period. To overcome this difficulty, a device called ‘Radiator Thermo-Valve’ is incorporated in the Cooling System, along with a ‘by-Pass’ circuit, with the sole purpose of enabling the Engine to reach it’s designed operating temp. (90* +/- 5*C) within a very short time.

Unfortunately, in a vast majority of cases, Owners/Mechanics/Authorised Service Centres included, continue to think out of the Amby/Fiat Era that this ‘Th-V’ is like a human appendix and has no useful purpose - other than ‘heating up’ the engine! Nothing could be farther than truth. To check whether this ‘Th-V’ is in place and in working order, here’s what you can do:

“First thing in the morning, BEFORE starting the engine after the overnight shut down, take off the Radiator Cap, keep the Bonnet open and then start the engine. Take a notch or so of the ‘Choke’ to keep it from stalling.

“As soon as the Engine fires, go across to have a look into the now open radiator neck. If you see turbulence/coolant circulation already, then your ‘Th-V’ is either not there (removed like an Appendix) or faulty (stuck in open position). If so, get it replaced at your Co. Authorised Garage.

While its being installed, as an abundant precaution, ask them to check the ‘By-Pass’ ckt. as well, to ensure it’s not blocked with sediments etc. If it is but not cleared at this stage, then with the new Th-V in place, the engine will throw-up Coolant right upto the windscreen when it warms up!

On the other hand, if the Th-V is in place and not faulty, you will see no circulation in the open radiator neck for quite some time. Then as the engine warms up, you would be able to see it setting-in ‘fits and starts’, including tendency to overflow from the neck. Just before that happens, shut-off the engine and replace the Radiator Cap properly”.

If the ‘Th-V’ is in place and working, the problem is somewhere else!

The most common possibilities are - a) The ‘Accelerator-Pump-Jet’ System of your Carb is either not working or mal-adjusted, b) The Vacuum Advance System of your Distributor is faulty, c) A ‘Retarded’ Ign. Timing and d) Your A/F mixture is set too lean (should be CO @ 0.5-1.0% for EU-I and 1.0-2.5% for pre EU-I Cars). Again it’s a common misconception that setting it ‘leanest’ possible gives you max mileage. On the otherhand, it results more in stalling when the Engine is cold.

If inspite of every thing being in place, a cold engine still has a tendency to stall - depending on Ambient Temps - then as the Owner’s Manual suggests - take a ‘notch’ or two of the choke for the first few minutes. This will not only prevent its ‘stalling’ but also help it to warm up faster. However, please ensure that you don’t forget to ‘reset’ it. If you do, you will not only be wasting fuel but also seriously cutting into the lubrication ‘film’ on the cylinder walls/engine life as well.

Next time, tho’ a lot more user friendly, we’ll talk about causes and cures of MPFi’s (BS-II/III) exhibiting such cold stalling symptoms.