Help! My 380SL keeps running hot. Heres the situation:

It first started about two months ago. The temperatue gague would read hot (near red) and then gradually return to normal. I would stop the car to examine. Everthing under the hood looked nomal but extremely hot.

I took it to the shop. The problem got worse after the radiator, thermostat and water pump was replaced.

Now after driving 15 to 20 minutes it goes hot and stays hot. I have to pull over for 30 minutes to let it cool down. Any ideas????

HC

 

You seem to have done the logical things.

Some thoughts:

The first thing to check is whether your gauge is reading accurately. Is the car boiling over or showing other signs of overheating? If not, have the shop check the head temperature once it's showing hot... they should have a temp sensor.

Even though it is new, the thermostat you installed may be faulty. Take it out, put it in boiling water and see if it opens. If not, then you have it. It's never a good idea to leave no thermostat in the car, so put a good one back in.

A car out of tune can create significant overheating. Check the timing and mixture settings.

With a new radiator and the above all OK, about all it can be is the water jacket in the block is probably choked with crud. You can try a two part flush but it may be that you are in for an expensive repair job.

 

I believe the gauge and thermostat is reading correctly. When temperature reaches the red zone, I pull over and look under the hood. No water spilled but I can hear the water boiling, the hoses are swollen.

I will try a flush!

But I am afraid you are right. I am in for a big repair bill! Great looking car but I think going to sell as is.

 

if everything else is working, you may have trapped air inside the cooling system and and the last one i did about a yr ago, i had to removed the valve from the thermostat and drilled the hole bigger and actually add another hole on it and filled the cooling system through the upper hose deatched from the radiator side and let it run for a while to bleed air out with the radiator cap loopse (first click position)try that and see it it works.

 

Could possibly be a head gasket issue.

Have you pressure tested the cooling system ?

I just did a repair job on a '96 C280 with the exact same symptoms you describe, the customer went to the dealer and had them install a new water pump, thermostat etc... and it was indeed the head gasket. I could have saved him a lot of money if he would have come to me first.

Easy way to tell is..... warm it up (to normal operating temp) and give it a compression test.