Originally Posted by
shogun
Yes, there are separate temp sensors, the one for the MOTRONIC is a different one. Maybe you change this one or might be possible to check it.
T-stats unfortunately are cheap stuff and often even new ones do not work properly or break, especially aftermarket cheap ones.
You can check it by usung a water pot in the kitches and heat the water up and check with a thermometer when it opens.
The symptoms - as you say - hint in direction of the fan clutch, but you say it works. Is the belt tensioner o.k. for that?
Is the auxiliary fan working in 2 steps, low and high?
Also check if the return hose from the radiator to the coolant expansion tank is clean and free, so that there is a constant return flow to the expansion tank. When you open the expansion tank cap, you should see a steady stream of return flow of coolant.
Gale has a good description on his page with pics, link on my website below.