Alan Smithee

The glowplug light is lit for about one second even in the middle of summer when the engine is fully warm, and will start fine without waiting for it to go out. How important is it to wait? If not important when warm, at what temperature is it pertinent? I'm religious about waiting for the light, but others not familiar with diesels won't have a clue (valets, friends, etc.).

Any thoughts? The owner's manual is very vague on the subject.

khaug

When we first got our CDI a couple of years ago, I tended to ignore the glowplug hold, as the car started fine without it. Then when cold weather arrived, the car would occasionally belch a cloud of blue-gray smoke on cold startup and run roughly for a few seconds. I puzzled out that this was happening when the ambient temp was 50F or below, began doing the one-second pause and have had no further problem. I think the engine was starting on less than six cylinders because I was skipping the glowplug pause, and the smoke was unburned fuel.

I doubt this hurt the engine, and it always started, so I'd not worry about valets or others not familiar with diesels. I think if the glowplug pause were critical, Mercedes would have built a delay into the startup routine.

This is all my surmise, so take it for what it's worth.

Regards.

Alan Smithee

Thanks for the response, khaug...that's the type of info I was looking for.

Any links to that 911 track car for sale?

H-townbenzoboy

This is true for older models, not sure about the CDIs, but you'll get better starting in cold temps if you wait to start it after the glow plug light has been out a few seconds.

khaug

Please check your PM.