When I bought my '79 633 about ten years ago, my mechanic did a pre-purchase inspection and told me it needed a new fan clutch.

The previous owner also told me that before I took it to my mechanic. I decided to put the replacement on hold and ten years later, I don't really see any signs of it getting any worse. It has never overheated, and I've never noticed any leaking fluid. I have noticed over the years, that the heater worked ok, but only provided lukewarm air.

I'm sure the wise thing to do would be to replace the fan clutch before a failure occurs, but I'm wondering if there are any other symptoms I should look for that would alert me to a worsening fan clutch condition.

Thanks -- any suggestions would be greatly appreciated.

Im not sure that the fan clutch has much to do with the heating system. A failing fan clutch would most likely be shown by improper fan behavior. Fan clutch isnt hard to replace, you just need the right tool, which is the big wrench...

Lukewarm air usually means something is wrong with heater core. Im not very educated on the heating systems of these cars, let alone on the older ones, which could have something different compared to 5/82+ cars.

-Jeff

10 YEARS LATER?!! good god

heater valve is a mechanical device on early e24 cars, Unless there is a problem with the linkage, it is performing. It should feel smooth as you turn it. That leaves heater core and air flaps/vents. If the core is relatively clear, I would check to see if the flaps are moving and operating properly. On second thought, where is the temp gauge reading ? If the car is not up to operating temperature due to a thermostat problem, that could be it as well.This is not a fan clutch issue

Let me add the simpleton's $.02.

I was having overheating problems with mine several years ago, went for a diagnoses, told that fan clutch bad. Changed fan clutch (Jeff's right, not hard, a little snug in working area though), no more over heating. :redspot