PeachParts Mercedes-Benz Forum - View Single Post

Tomguy · #4 01-10-2009, 10:05 AM

The aux fan not working combined with a weakened fan clutch (they wear with age or lock up, yours sounds like it doesn't grab anymore) results in overheating at idle, and when you begin moving over 40 you see the temp drop rapidly. That's a telltale sign of fan failure. Even a new radiator won't help that situation. You really should replace the front aux fan with a good used one, and the fan clutch (with a used one if you're on a budget). The radiator must be from a 3.5 or a 4.5 108 or 109. The inlet or outlet is on the wrong side from the 6-cyls. I forget which. It's also substantially smaller, a leaky 4.5 radiator with corrosion probably still cools better. I do agree with the cap suggestion, mine leaked from the seam too. Make sure you fill the radiator all the way up to the indentation inside (it looks like a wedge-shaped notch from the outside, on the engine side of the radiator). Not doing this results in rapid overheating because your coolant goes through only about 1/4 of the radiator.

If you're on a budget you can fix a seam leak yourself if you have moderate technical skills. I used silver solder and a ton of flux paste and did mine, and it held for well over a year until I decided I wanted to fix a tiny tiny leak on the end and wound up messing it up beyond the point I could fix it with my then-limited resources (no garage to shade from wind and no dremel to clean out the old paint and rust).