I had the same problem last year. And I replaced the fan clutch - No help.

I get the feeling that your cleaning of the radiator was with the radiator STILL IN THE CAR.

Try this before you do anything else. Drain and remove the radiator, use a high pressure hose (be careful not to bend fins) and clean the radiator. Re-install refill and go...

I did this - and I couldnt see any dirt in my radiator either- and tons of dirt came out. The car has been perfect for over a year even in 10o degree heat w/ AC. The cheapest repair ever-which is why you probably think it wont work.

It definitely sounds like the fan clutch. I had an '89 244 with the same symptoms. I did what you did ... replaced the t-stat, took out the radiator and cleaned it out. Still had the overheating when ideling w/ ac on. The fan clutch was the culprit. You can get a new one (Aisin) at FCP Groton for a good price ... I think around $50. Plus it's a real easy fix. As far as electric fans ... you might want to think about installing a pusher fan mounted behind the grill. This is stock on the '91 - '93 models.
--
Bill Crump - ('91 245SE & '93 244 "Classic")

Does your car have the 'pusher' fan in front of the rad? Not sure what year that started, but I'm pretty sure at least the 91's had it. If your car does have it, then find the pressure switch on the right frame rail just aft of the rad, and jump the two wires. I simply removed the connector and made a jumper from some 16 gauge wire and plugged it into the receptacles in the connector, then taped it up with electrician's tape. I also taped over the connectors on the prressure switch to keep them clean incase I need to reverse the procedure some day. The point of bypassing the pressure switch is to force the pusher fan ON whenever the AC is turned on, which will help a lot with cooling.

Now if you don't have the pusher fan, you could try the boneyards (and maybe get a spare fan clutch, just in case)to find one, or visit the turbobricks web site for details on the complete electric fan swapover.

Also, remember that in a pinch, if you're on the verge of overheating, turn the heater control on FULL and run the fan at top speed. You won't be comfortable but you can dump a lot of heat this way and maybe prevent some serious damage.

regarding your post, it sounds almost exactly like the scenario that my car went through last summer.. i live in california in the motherlode gold country, so it gets pretty hot here, with the average temp in july being over 95.. my car was way overheating, especially when i had the AC on or when i was sitting in traffic,so i replaced the thermostat, but it kept overheating in traffic, so i figured the fan clutch was bad.. i never did get around to fixing it, though, because my AC went right after that... my suggestion would be to take off the clutch fan entirely and buy an electric fan from summit racing with a thermostatic switch... its not that hard and it helps with taking a load off of the engine, which frees up horsepower.... ive got an electric fan on my '71 chevy k10 pickup and it really does help... but it also has over 300 horses too... hope you get it fixed..


JT