gta892000

On the passenger side head secondary fan temp switch:

There's no gasket washer or O-ring in the box or on the old one.

Is it supposed to go in with nothing on the threads and no o-ring or washer gasket?

Now that I think about it, isn't that a bad idea, since it is supposed to ground when hot? I'll check to see if it is grounded by the threads cutting through the teflon tape when tightened.


I mistakenly put it in out of habit with some teflon tape.
Will it matter if the teflon tape didn't let it ground? I'm going to check that to see if I really do have to remove it and do something else.

The old one looked like tapered pipe thread, but the new one doesn't appear to be tapered at all. I suppose I should have found an o-ring or rubber washer gasket to fit instead?

I'm wondering what the correct installation is supposed to be so that it doesn't leak.

Do the computer controlled adjustments not getting that ground do anything else when its hot or is it only for the fan?

Thanks.

NCC-2569

iTrader: (1)

Warm up your engine and then turn on your A/C. That switch reacts to coolant pressure and should then close to ground and throw the second fan into motion.
That's if you have a second fan. No idea what engine you have there.
Anyway... mine didn't come with any o-ring and I also don't recall seeing sealant on it.

gta892000

the engine is a 350 and it has AC with the dual fans

all set, the threads cut through the teflon

according to my ohm meter
from the ground strap on the back of the head to the nut part of the switch is zero, so it should be fine, I think

what's the proper tool for removing that? I just jammed a 7/8 deep socket onto the old one and used the same thing to put it back, seems like its not quite 13/16th...

anyway, its all set for testing as you recommended
going to try to start it for the first time since replacing the head gasket
onward to setting the timing next

thanks.

NCC-2569

iTrader: (1)

Glad it worked out!
I think that sensor needs a metric socket, but you should be ok with the socket you used.

Ozz1967

iTrader: (4)

You want a light coat of Teflon tape around it, but not enough to prevent the threads from making contact. Without this bit of Teflon, you may leak coolant around the threads.

The switch heats up and grounds the wire internally to the block when it gets to temp. That sends the signal to the relay which switches, thus turning on the fan.

You can check the circuit, by turning the key to run and grounding the wire to chassis ground. If the fan comes on, then you know the circuit is good. Then if the fan doesn't come on at the temp the switch is rated for, you know the switch is bad.

gta892000

thanks.

I'll test it.