Hi everyone,

I have a 1978 450SL. Recently, the engine has been dying at the end of a long trip on a day when it's warm out (I'm in northern california). For example, I drive the car 30 miles on the freeway and although it runs great at 70mph, when I get off the interstate the engine shakes at the first light then dies. I am convinced the issue is not overheating, although that appears the obvious answer. The temperature gauge works and not only does it not go into the red, it doesn't go near the red. It hovers between the third and second to last hash marks on the temperature gauge. The coolant system does not appear to be the problem. Something else is failing which is being triggered by heat.

However, I know the problem is heat related as I can drive the vehicle for long distances in the cool night and I do not have this problem. The failure happens during the day after a long drive where the temperature in the engine gets hot. Obviously, when I get off the highway and no longer have the air blowing the car gets hotter triggering something that is failing.

Does anyone have any ideas what are some possible problems here? The mechanic and I are totally mystified.

thanks

Peter

 

I had a similar problem and the catylic converter was plugged.