I told him to keep it under 105C if humanly possible - that was good info. He's got a temporary thermostat from Autozone (hehe) and is installing is right now as we speak.

What's the procedure for verifying the fan clutch is working?! How can he check that? I'm looking at an online manual: http://www.ps2cho.net/downloads/MB%20CD/W124/Index/602_603/20CoolingSystem.htm

Procedure: # 20-310 - Temperature-controlled viscous fan coupling - is this the one...?! It says in there:

"Run engine at 4000-5000 rpm. Once a coolant temperature of approx. 90-95C has been reached, the speed of th eviscous fan coupling must increase, which can be clearly heard"... so if I understand correctly: warm up the engine to normal temp, then rev it up to 4000-5000 rpm and observe the fan - if the fan speed increases then then clutch is working, Ja?!

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K