Hi Folks,
I get stuck sometimes (often) on the way back home from work in the miserable traffic on 101 across the GG bridge and in the summer it can get pretty hot. It kind of pissed me off that the fan on my 87's front cooler would never turn on, so I decided to do something about it. In all my time of owning the car, I'd never heard it once.
I've read that the factory's t'stat only turns on the fan at 244F, which is way too hot, considering that there's probably a 20-30F temp difference between engine oil temp and temp at the cooler itself from heat transfer along the lines.
I'd read somewhere here that there's a BMW t'stat rated at 194F with the same thread pattern that can be installed, so I ordered one from our host and installed it. It's kind of a b!tch actually...
I put the car up on the lift and pulled the R front wheel to have a look. You need to remove the horns and their bracket, which is held on by three 13 mm bolts, one of which attaches to the bottom of the headlight bucket. It helps to remove the wiring from the turn signal and running light, and the aluminum reinforcement bar which runs along the inside of the bumper as well, which is held on by two long 13 mm bolts.
With this business out of the way, and your eyes full of grit, you can being wrestling with the cooler. It's held on by three 13 mm nuts. Two on rubber-isolated mounting studs at the bottom, and a third at the top. I removed these, as well as the oil cooler line brackets in the fender well, but couldn't get enough movement to wiggle it off the supporting studs on the bottom. Finally after much cursing, I managed to pry it off there by using a large screwdriver between the cooler and the lower mounting bracket.
Here are the two t'stats. The BMW part is on the left. Note the shorter extension of the temperature sensing element. Doesn't seem to have caused a problem.
Here's a view looking up at the t'stat after installation. Note Porsche's strange arrangement of the ground connection, which is actually mounted on the cooler itself, while the power connection with the blue wire has the odd cylindrical connection pictured dangling in the front. BMW uses the more traditional spade connectors, and has both connections on the t'stat itself, so the power connection had to be modified to fit.
When you go to replace the cooler, I recommend you slot the lower mounting holes in the cooler like this with a dremel or whizz wheel to avoid the pain of trying to pry the whole thing back into place again. Why didn't Porsche do this? You can see the scars from the original removal:
My sealing gasket around the periphery of the cooler was pretty much non-existent, so I ordered a foam seal for an aircooled VW bus. This part fits the 72-79 type II, and is used to make a seal between the the engine tin and the body. It's slotted on either side, so it's a pretty good fit. It was about $35, and best of all, it's about twice as long as needed, so if you screw it up, you can try again:
After finishing, I finally heard the thing go on in traffic a couple weeks later when there was an accident on 101 and I'd been idling for a half hour or so just creeping ahead on quite a hot day. It finally turned on around 220-225F engine temp.