High engine temps SOLVED!

[BongC36]

Ever since I got my C36 I had been concerned about the high engine temperatures that I normally experience, which ranged from 95C to 110C. Once, It even went up to more than 115C, when I met with heavy traffic afer a hard run.

While I have read many times on this and at other forums that it is normal for MB's to reach even 120C, I am not really comfortable seeing the needle so close to the red mark. I have experienced many warped heads and blown gaskets due to overheating on my other cars, and performance suffers as the temps go up.

I am sure that there are many here who share my preference for lower engine temps.

First thing I did was to install a manually-controlled relay that turns on my AUX FANS at stage 2 (high). This is my insurance policy since this relay is fed directly off a solid +12VDC source.

Next, changed the coolant with genuine MB stuff, mixed 55/45, and made sure my system holds pressure. It does, no problem.

I then installed a BEHR 71C thermostat. While this solved the high temps, I found that the engine took too long to reach even 80C, and that at speed the temp drops to 70C! This is bad since it accelerates engine wear and the fuel mixture is set to rich so I re-installed the old but functional BEHR 87C thermostat.

Still the temps were high. I next replaced the functional OEM viscous fan clutch with a SACHS tropical version. Sucess! Now temps ranges from 85-90C in traffic or freeway, motor feels more powerful, and I can relax knowing I am far away from the red zone.

This tropicalized unit has a lower lock-in setting than the standard clutch. Part number is 2100 006 243.

Cheers!