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).
425 White Horse Pike
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.
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.
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 <3K miles.
'83 300DT 332K
'85 300DT 224K
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.
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