84 4ksq Radiator Fan Question...How High?

[Huw Powell]

> I’m beginning to suspect that the radiator fan in my 84 4ksq is not going to
> “kick-on” soon enough to avoid blowing the (upper) radiator hose.  All
> connections to all fittings appear to be solid…and I even a have a few
> relatively recent electrical components in the cooling system.  I’m losing
> my nerve relative to sitting in the car watching the temperature gauge and
> keeping my fingers crossed that the hose doesn’t blow.  I let the gauge go
> at least ¾ of the way up.  Should I just stop whimping-out and let it
> go?...or is there a quick way to by-pass the rest of the cooling circuit to
> check the function of the radiator fan? 

The sender for the fan is in the bottom rear of the radiator.  Shorting 
its connector out should make the fan run.

The sender does this by turning on relay #2 which sends battery power to 
the fan.  That relay should also be tested or replaced, and can be 
jumped to, again, run the fan.

You can also run heavy jumpers to the fan motor directly from the 
battery to see if it runs.

While running the engine up to that 3/4 position on the gauge, you can 
measure the sender's resistance, it should go from infinite to zero at 
some point.

You could remove it and test in a pan of water as you boil it, but then 
your coolant would pour out of the radiator.  Unless you have a spare 
sender to screw in its place quickly.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/