BenzWorld Junior Member
Date registered: Jun 2019
Vehicle: 1977 450SL
Mentioned: 0 Post(s)
Quoted: 11 Post(s)
Yet another 450SL running HOT thread
Hi. I've read so many threads here on the subject of 450SLs running hot.....
I have a 77 450SL with 57,000 miles. I am the third owner.
In the cooler months, this car has had some "good days" running at about 185-195 degrees F. But it did have a tendency to get up to the 212 line, especially while driving on the freeway. At times, I feel this car is bi-polar.
I foolishly went "ALL IN" and replaced the radiator, water pump, and thermostat and saw no change whatsoever. I had a system flush don3 on the car as well.... no change.
I read several threads here on ignition timing and had Goody's Automotive look into it. I am told that the timing is set properly.
A typical drive starts just fine. Once I get to speeds of 55 MPH or higher, the temps slowly creep up from halfway between the 175 and 212 line up to the 212 line. Once the 212 is reached, the needle hardly ever goes back down, even on the freeway. This behavior is the same if the AC is on or off.
So.... New Radiator, Fan Clutch (well.... a new one only made the car sound like a Mack truck and improved NOTHING so I put the old one back on)... New water pump, new thermostat, chemical flush.....
What else should I look into?? Summer has finally arrived and the needle is going past the 212 line. I pointed an IR laser thermometer at the top of the radiator and got a reading of 220F.... I know there is a solution but I cannot seem to find it. The aux fan kicks in but does not really seem to have any effect on the temperature.
I am not loosing any coolant and there is no white smoke coming out of the exhaust so I don't think I have a blown head gasket.
Any thoughts? I am at a loss!