Don Can you help? Phil refered me to you

190e is still over heating.

My specific questions are
1.) how do you test the auxillary water pump?

2.) how do you test the viscous fan clutch?

3.) Is the fan shroud cosmetic / saftey or does it improve the vaccum effect from the fan clutch? e.g. does it have to be there?

3.) Any other suggestions or Ideas?

Here is the history:

car: 190e 2.6 1993
Problem: car overheats and/ or runs right beneath red temp line only when it idles or I sit in traffic for more than 10-15 minutes or if I'm driving slow (e.g. rpms <2000rpm). This occurs regardless of outside temp.

The temperature rises much faster if the heater is on. No difference with the AC on.

I have found that after running the car such that the temp rises to 80 dergrees C, and let it Idle. The temp begins to creep up rather quickly up past 100 C (it will overheat if I let it go). The auxillary fans kick on but does not cool the temp down. If I then rev the rpms to 3000 the temp quickly decreases to 85-90 within 30 sec to 1 min.

Operating temp when driving is just a touch above the 80 degree Celsius mark. No problems what so ever when the car is moving as long as the RPMs are greater than 2500-3000.

Recent work:
1.) replaced the water pump with an OEM graf water pump, changed hoses

2.) changed radiator fluid (40:60 anti-freeze to H20 mix),

3.)tried both the old Mercedes thermostat and a wahler thermostat. (boiled them both to make sure they open)

There are no leaks in the system by visual inspection.


Please help

Thanks

Aaron