1stmbenz

I have a 93 400E. I notice sometimes when I've driven for awhile on a highway, I see steam from under the hood. The last time this happened I stopped at a gas station, I was able to see steam coming from the back part of the engine. I haven't been able to pinpoint the hose or connection thats causing this problem. Any suggestions would be appreciated.

Jer

I can think of two possible causes. The worst is that your head gasket is failing, and allowing water to escape the engine and be boiled. The other, less severe, is the supply hose for the heater core is cracked or came loose.

Kestas

I can think of two ways to look for the problem. One is to try to follow the steam to its source. Park it in a dark enclosed area after driving and using a trouble light and perhaps a mirror, try to pinpoint the source. The other is to pressurize (15-20 psi) the cooling system with shop air and search for coolant weeping from the leak source.

I don't know how many miles are on your car, but after 10 years it wouldn't be a waste of money to just go ahead and replace the heater hoses.

1stmbenz

I'll get my mechanic to change the heater hoses. Thanks.