At what temperature should I plug in my Mercedes diesel?

Answer 1

I say anything below 20 F it will start at lower temps but it is better for the engine if it and the oil are already somewhat warm before starting.

Answer 2

These people have no idea what they're talking about and are completely clueless as to how a diesel works. ANY TIME it gets near freezing temps you should plug it in. For one your fuel begins to gel up at about 15 degrees F and if you don't put in Alcohol additives in your fuel your asking for it to gel. If you put in addatives then you could but shouldn't wait until -10 F. Two is your diesel doesn't ignite like a gasoline...IT DOESN'T HAVE SPARK PLUGS!!! Gasoline begins to freeze at somewhere close to -40 degrees F. This is why you can start your gasolines in the cold morning with out pluging them in. Diesel fuel freezes at about the same point of water....your always going to have some water in your diesel and we all know waters freezing point....so you wait however long you want to plug it in.

If you don't plug it in before it begins to freeze your really going to cause some damage to your rings and burn oil....severly. Basically the colder the air becomes the more damage you will cause. Your diesel will obviously start in cold temps....but when you crank on it for that long in the morning....you are damaging your starter windings, piston assembly, guming up the rings, pressurizing your crank to a small extent (creating high blowby on high mile engines...At this point your increasing your chance for a run-away engine), and injectors (from burning oil). A run-a-way is where you are running off your own engine oil...in other words your key won't turn off your engine!!! Most people RUN away at this point.
This is why it smokes really bad in the morning...when you don't plug it in. You shouldn't have to turn your glow plugs on multiple times just to get it to start....if you have to do this then it is a good indication that you need to obviously plug it in. Starting a diesel in cold ambient temps will cause premature wear to your engine in the long term.

An engine is considered warm at 140 degrees F.....anything below that is a cold engine. Be sure that when you plug it in that it maintains this approx. temp

Answer 3

I find that they start fine down to 0F. In the worst case, you may need to repeat the glow cycle two or even three times. If you're execting this sort of weather, change to 0W-40 synthetic for the winter months, it really helps cold cranking.

Answer 4

I own VW TDI, it doesn't have any heating system.. this winter it's been -15C to -20C, some morning it's hard to start but it does start.

just make sure your glow plugs are fine and it should start ok ;-)

Answer 5

-0. They will start above 0.