300D and the cold

The theoretical starting limit of your car is about 0 degrees F. So at six f., everything must be perfect including engine, battery, fuel, oil. Adjust the valves, add gasoline or kerosene to fuel, have a perfect battery and glow plugs, and use low-viscosity oil (I like Mobil 1 0w40). Bill Ditmire Ditmire Motorworks,Inc.

Diesels are compression engines - they compress air to the point where its heat will combust the fuel. Glowplugs are added to help start the engine. Worn engines have lower compression than new ones so there's less heat to ignite the fuel.

Charge the battery. Glow the engine several times before cranking it. Floor the accelerator when cranking. It should start.

I didn't realize that the theoretical limit (is that according to Mercedes?) of my diesel was 0 degrees F. I've started my 1980 300CD at -25 which was bad enough. But I was also at 9,500 feet where the reduced atmospheric pressure even makes starting harder. I had a difficult time starting under those conditions. However, since I rebuilt my 617 engine, I've started the car at

-15 F on the first turn of the key at slightly lower elevation.

DO NOT FLOOR THE ACELERATOR!, too much fuel will enter the cylenders and combustion wil not occur in cold weather. After glowing, crank the engine without touching the accelerator, the engine will fire but will not catch, keep cranking for another 10-15 seconds, you will notice the engine starting to catch, keep cranking and slightly press the accelerator the engine will start and run. This method will work on a stone cold engine in good condition down to -5 deg F. Of course the battery needs to be good and the oil needs to be

Logical but contrary to '80 300SD Owner's Manual.

For the first time in four+ years, my '84 300D wore the battery down just before it could kick off at 7 degrees last week.... even then with a jump it took off after another 10-15 seconds of cranking. It turned out that one glow plug was dead, but since they had apparently never been changed I replaced them all (AutoZone sells Bosch for $10.99 each) along with the relay. It still cranks a long time at those temps, though!

I really prefer PowerService conditioner, by the way.... AND

Make sure you're getting your fuel from a good source. I had just bought some fuel from the new Wal-Mart station and their tanks gelled up that same day. Live and learn.

Bervis wrote:

The solution is called a 'block heater'. Starts my 300TD in -10 weather (though sometimes the fuel gets a bit jelled at those temps).