a MB thermostat, so you dont think its the RAD? what about that wirring harnesst , i heard they are bad for those.. would that cause it?? if it was the head gasket it would be oil and coolant mix,/ or leaking from the gasket external or burning it, but i dont see white smoke , nore any loss of coolent. hmm maybe fan clutch???

thanx for the replies by the way

The wiring harness should not cause overheating, but it may cause a false reading on the meter. If you suspect this, check temperature around the engine, and especially at the thermostat housing with a non-contact pyrometer.

Bad grounds between the engine and body can cause false meter readings. If this is the case, there may be a difference in readings when the electrical consumption changes.

However, if your radiator is original, it could very well be the problem.