Minor Starting Problem Today With 300D
 

This morning was the coldest since I've owned the car (40f). I let her glow for 5 seconds after light turned off, cranked and fired right up! however, after about 2-3 seconds, she quit? I glowed again, fired up and off we went on our 75 mile commute. The same event occured on the way home this evening. Am I right in assuming my glow plugs are bad? Even though it started and ran for a couple seconds? Thanks

You should start your car as soon as the light goes off...by waiting 5 seconds you have let the glow plug cool off.

The glowplugs should stay on a while after the light goes off. More likely the problem is dirty fuel filters or an air leak in the suction line. A friend on mine always changes his mother's fuel filters every fall, she no longer has starting problems.

A rotten suction line will cause air to get trapped in the injection pump, and when cold with the concommitant poor initial combustion, the engine stalls.

The glowplug light doesn't blink once in a while does it? If it does, you have a bad glowplug. You may, anyway -- I had terrible starting problems with the Volvo, turned out to be the Champion glow plugs I put in (same part as for the MBs) -- filament pulled off the end, leaving a nice little hole, and welded to the side. Still pulls current, but doesn't heat the tip, won't start. Inadequate glow plugs will certainly cause stalling a few seconds after starting -- usually also cause rough initial idle and while smoke.

Peter

My bad Guys!! I feel stupid, but my answer awaited me in the owners manual. I guess I have to pump the gas pedal a couple of times during cold start. So I did, and the car started fine and continued to run fine. Duhh! Although I still think my glowplugs could be on the way out. Thanks again.

Waiting a few seconds after the glow plug light goes off is a good idea
 

in cold weather. It's true that the plugs no longer get current and begin to cool, but their heat is being transferred to the air in the prechamber, which is exactly what is needed to start the car.

If you listen very carefully, you can hear the glowplug relay "clink" as is shuts off, well after the light has gone out. ( at least another 20-30 seconds, but possibly up to 90 secs.)

-Larry

You beat me too it, Larry, the light is only an indication, you can hear when the relay drops out.

There is a circuit that provides a fast idle for startups (Cadillac uses a similar system, btw if anyone cares). I am told it is a high failure rate item, and apparently mine has failed, because I always have to put a little pressure on the accelerator pedal to rev the tach up to about 800-900rpm until the engine holds that idle speed by itself. However, as the repair part is around $100, I feel confident in my ability to provide a "manual" fast idle for startups...

You might also want to change your oil to winter weight (10W30), or to synthetic, for easier starts.

Peter

psfred,

You have been posting a lot today that hasbeen sparking my interest... You asked about if the glow plug light comes on once in a while, indicating a bad plug. Is there any specific timing as to when it would light up?
I knwo this summer when I would be commuting very early in the morning, my seatbely light would often blink even though it was attached, but sometimes the glow plug light would come on, which I thought was quite odd. but it was completely random, and often it would not even light up all the way, it would just flicker a bit then go out.
Any info on the glow plug light would be appreciated.
Thanks

JMH

Alan S,

If you engine starts easily, the GP have done their job. They are shut off when the engine is running therefore have no effect on the engine after it is running.

Stalling when an engine is cold is normal if you don't rev it up a little.

P E H

I'm not sure of the exact sequence, it is different for different models, but I think that if one plug is out, the lamp will flash after you start, if two are out, the lamp doesn't light, but flashes after you start, and if more than two are out, never comes on at all. Distinct one second or so on-off sequence, not dull glow.

I would suspect you have a loose wire on the ignition switch or on the glowplug relay, so it gets false on/off signals, or a bad ground in the dash so that you have current backfeeds. I had a bad ground on my Volvo headlight, left side low beam -- caused the dash lights and gas guage to "flash" with the turn signal, all four lamps were on, very dim, on low beams, and would go out with the flasher. Put the ground wire on a good terminal, entire problem vanished. Weird.

Peter

Could someone explain what the 'increased idle speed' system is on the newer 617's without the manual idle control knob. Mine may not be functioning wellon my 85td.
On my 77 300d if I try to start immediately after the glow plug light goes off it takes a few revolutions of the crank before it fires up. If I wait 40 seconds it starts on the first compression stroke. So, the glow plugs can't be cooling down in that period.

Kerry is right. The GP continue to heat until the relay clicks off and not when the dash mounted GP indicator plug goes off.

The longer the GP are on, the quicker the engine will start.

P E H