White smoke in exhaust but no overheat
 

For a couple days, I noticed my 1993 300CE "radiator" light was illuminated on my dash. I topped up, and was fine for a couple days. Suddenly on starting up last morning, my tail pipe started spitting out white smoke and would not stop even though I drove about 15 minutes. The overflow tank was empty when I checked it, however I never ran hot. No oil in overflow tank either.

What can this be?

Sounds like a head gasket - coolant is leaking into a cylinder. Compression/leakdown test and cooling system pressure test can confirm. Suggest you stop driving it until the problem is corrected. Coolant leakage into a cylinders will eventually damage the wall, and at that point it will get A LOT more expensive.

Duke

I think it does that when a German Pope is selected. Sorry, couldn't resist.

MP

Once and Done
 

My water pump was leaking and I added water every time the light would come on. I didn’t drive more than about 5 or 10 miles at a time until I could get the water pump fixed. My car never overheated, but I suppose it would have if the water level ever became too low.

Your car probably won’t overheat until the fluid gets to low, but I think you do have to hurry and get it fixed. It is definitely a bad idea to let you car continue to burn the radiator fluid. I think you can get all kinds of deposits around the aluminum head and then it may have to be machined to get it straightened out. I think you will just add to the expense, if you continue to drive the car.

From what I have read about improvements in the gasket design, it sounds like the head gasket fix is a once and done job, so just figure it will be good for 200,000 or 300,000 more miles once you get it fixed.

I would bet that you have a leaking head gasget. Try holding a kleenex in the exhaust stream... if it disolves > you have water vapor coming out the exhaust... which means there is coolant getting into the compustion chamber>> which means blown head gasget.

Me too.
I agree.
I disagree. Water vapor is a normal byproduct of combustion, as evidenced by water dripping from the tailpipe of most cars. White smoke is more than water vapor, it is steam and burned coolant residue.

Don't wait too long to stop the leak, as the coolant in the combustion chamber is not going to do good things to rings and valve seats. It will eventually find its way into the oil lubrication system, with equally not-good results.

Best Regards,
Jim

Had this problem a couple years ago and changed head gasket. That time there was oil in coolant tank, overheated but no white smoke from exhaust.

My mechanic seems to think this time may be a cracked head :mad:

did you have to replace the water pump too?
what causes blown headgasket; how can it be prevented?