Hey all, I wanted to see if any other E300 or diesel owners have had an issue similar to this. My E300 runs great, it has new GPs, new seals, new gaskets, new filters, etc. However, it has always done the following: whenever going downhill on the highway for an extended period of time, the engine will kick out lots of white smoke when I accelerate. The smoke stops if I let off the gas, but the second the pedal is pressed down again it will smoke for a bit. This goes away after a certain amount of seconds, usually proportional to how long the previous downhill descent was. I can really notice this on I70 in Colorado, where there are long stretches of decline/inclines.

I also got off the highway after one of these downhill descents, and noticed once coming to a stop the engine was idling bad, missing every few seconds. This particular aspect would only last for 10 seconds, then go away.

I read a few articles of other diesels doing similar things in the Alps, and they were saying that the engine/exhaust cools so much that a vapor is produced when you step on the accelerator, almost akin to typical cold start symptoms.

Again, she runs fine when driving in the city, on generally flat land, and going uphill.

Thanks for your help all.

Similar issue - i can see oil being drawn into turbo. Prevalent on downhills and cool weather only. Any guesses?

I have never heard of this particular problem in this car but I can tell you a couple things about the engine that might help.

The fuel rack closes when you let off the accelerator and essentially shuts off the engine. If you spend any length of time coasting down hill, the exhaust temps can get down to the air temp and any oil that has leaked into the engine at that time will be burned all of a sudden when you come back on the throttle at the bottom of the hill.

There may be a seal leaking in the turbo or it's possibly vapor coming from the CCV system simply flowing through the engine and depositing in the exhaust.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250