Well, went to MB yesterday to buy the new rad cap. Here's the scoop.
- the MB thermostat opens at 84 degrees celcius.
- I bought a new rad cap and put it on yesterday.
- the car is a 1982 380 SEL.
- I bought it from a friend's dad who had it serviced at MB for 25 years! (Incl. all oil changes)
- MB printed out the service history (39 pages.)
- aside for some other major MB service (tranny, timing chain, etc.) a new MB rad was put in at 190, 000 Km (present milage is 224 K)
- the parts guy I spoke with suggested all of the same things that have been mentioned in this thread. (Fan clutch, thermostat, he was doubtful about the cap, but it only costed me $12 CAD)
So, yesterday was pretty much the same as the day before. No heating problems while driving around the city. I didn't drive up the hill until late at night, (and it was quite cool last night) and although the temp did reach above 100 degrees, she didn't boil.
To recap...I've changed the thermostat, and now changed the rad cap...and still no noticable change. My main problem continues to be overheating when driving up a long steep hill.
I've checked the fan clutch, and the fluid mixture and it's very clean. The rad looks clean but I may try to leave it in and just spray it down today followed by air from a compressor.
Thanks to everyone for following this thread and assisting me with the problem. Where should I go from here? I love this car, but never had problems like this with my Toyotas!
Brad.