andrew strasfogel wrote:
OK, I have a puzzler. Let's see how good you all are. FIist correct reply
wins a FREE Puccini coffee (must be collected in Washington, D.C.)
1985 300CD. For the past week we plugged in the block heater and the car
started instantly and perfectly in gtemps. as low as 10 degrees F.
Yesterday, the alley was iced up so we had to park on the street overnight,
with no way to plug in the block heater. Temp. was 17 degrees this AM with
a wind chill of maybe 5. We glowed and kept glowing 10 seconds after the
light went out. Engine turned but would not fire. Tried twice more, using
the gas pedal, but to no avail! I had her pop the hood and try a fourth
time while I watched - still turned but no dice. Battery was strong,
fortunately. I stared at the engine, thought deeply and then fiddled with
something in the engine area. I then myself tried to start it again using
the same preglow procedure. This time the engine fired instantly and ran
flawlessly.
There is ALMOST nothing in the engine compartment that influences cold
starting.
Was the hand pump tight and/or did you pump it? Was the glow plug fuse
tightly secured?
What you describe can happen if there is a little water in the fuel or
the cloud point of the fuel isn't quite high enough. By the 4th-5th try,
the ice or wax that was blocking unrestricted fuel flow may have been
displaced. What you describe can also happen if one or two valves are
just a tad tight (so that compression is down just a bit). ANYTHING that
warms the engine even a little can turn a non-start into a start if you
are close.
You said that you depressed the accelerator pedal at least once before
trying to start (to be sure the rack was off the stop position) and held
the pedal at least halfway down while trying to start!
I continue to be dumbfounded that almost nobody follows Mercedes'
recommendation that once you start cranking, KEEP cranking until the
engine starts - DO NOT STOP CRANKING - DO NOT TRY A SECOND TIME (as you
would with a gasoline car) - just keep cranking until the engine starts
or the battery goes dead. That offers absolutely the best chance of
starting the engine in really cold weather. Any other strategy offers
less chance of the engine starting.
You MUST of course do all the proper preparation before you start
cranking. That includes insuring that the fuel is properly winterized
and free of water, the battery is properly charged, the preglow system
is working properly and the valves are adjusted so that none of them are
tight. Then the pedal must be depressed to the floor at least once (2 or
3 times won't hurt) and the pedal held at least half way down while
cranking. I try to insure that the total preglow period before starting
to crank is close to 30 seconds (that allows the plugs to reach their
maximum 1180 deg. C. temp) and then I start cranking until the engine
starts. If the actual temps are below the minimum start point (without a
block heater) which is between 10 and 15 below zero F for my OM60x
engines (with Mobil 1 in them), then I either need to use the block
heater or at least blow heated air (say from a hair dryer) into the air
intake for 3-5 minutes before I try to start the car.
Marshall
--
Marshall Booth Ph.D.
Ass't Prof. (ret.)
Univ of Pittsburgh School of Medicine
[EMAIL PROTECTED]
