My 1994 s600 is overheating. Its done 140,000 miles.

On the motorway, at 80mph the temperature is around 100 centigrade. Any faster and the temperature keeps rising (although not into the red). There is no loss of oil pressure. The fans kick-in at around 115 centigrade. If I put my foot down, so that the kick-down comes in, the engine will only rev to around 4,000 and then seems to slip into neutral and misfire (some sort of self-protection mechanism?) - it doesn't redline as it should. Its normal running temperature is around 85 centigrade.

This all seemed to start after I drove on the motorway at around 80mph in third gear with the aircon on its coldest setting - by mistake.

So far, I have taken the thermostat out (and not replaced it yet). Also, after a long run (i.e when it is overheating) there doesn't seem to be any water in the main pipe leading from the thermostat housing - It is cool enough (just) for me to squeeze it and I can feel that it is empty. There is normally water in it (when cold), so I don't think there is a blockage (happy to be told otherwise).

Any suggestions gratefully received. I read somewhere that it might be worth disconnecting the battery to reset the computer.

Thanks

Graham

 

Probably it's time to change the radiator

 

Sounds like you have a "bubble" in the cooling system. Take it to a place that can flush and fill the cooling system.

 

check and make sure your water pump is turning, make aure your water reservoir cap is ok (rubber seal) after all is ok just pump the system by pressing the hose and release just to let the air out of the system, try it