bad fan clutch?

[mcditalia]

How do I know if my fan clutch is bad? How much play should it have? Any sure ways of testing/knowing?

My car was hovering around 220-210 tonight the whole time I was driving around town. Even when going above 40 mph, it barely dropped, which it never does. I have a feeling the fan isn't turning right. Car has a new water pump, radiator and 160 thermostat. When the car is turned off, the fan keeps rotating for 3-4 seconds. Normal?

 

[geekinavette]

It may have lost the silicone fluid...look for signs of fluid on the clutch somewhere.

When the engine has been off for a few minutes then try to turn the fan...if it seems to have no resistance then its time for a new clutch.

 

[mcditalia]

thanks for the response.

There is some resisatnce but doesn't seem like much. I thought I read somewhere how to gauge the resistance after you shut the car off and how long it keeps spinning, but cant find any old posts about it.

 

[Rex S]

Fan clutch has zero play in any direction. On the front there is a spring (some are flat coil and the other is a flat spring) any oil on the outside is a sign the clutch is on its way out. It's a silicone based oil in a very small amount so any leakage will make it operate poorly.

 

[JohnZ]

How do I know if my fan clutch is bad? How much play should it have? Any sure ways of testing/knowing?

My car was hovering around 220-210 tonight the whole time I was driving around town. Even when going above 40 mph, it barely dropped, which it never does. I have a feeling the fan isn't turning right. Car has a new water pump, radiator and 160 thermostat. When the car is turned off, the fan keeps rotating for 3-4 seconds. Normal?

With a correctly-operating fan clutch, the fan shouldn't rotate more than 1-2 revolutions at most when shut down hot; yours is definitely in need of replacement. What kind of new radiator do you have?

 

[mcditalia]

I replaced my radiator with a correct repro from dewitts radiators.

The fan clutch assembly got tighter when it cooled down. Should it have zero play when hot and cold? The clutch is correctly dated. Where can I get a rebuild and how much will it cost?

 

[Hib Halverson]

As others here have said, a fan clutch should have zero play.

That said, know that above 35-40 mph, the fan has little effect. If above 40 cruising on the road and the car is running that warm, there's a problem somewhere.

Is the front air dam in place and functional? Are the rubber sponge seals which prevent air flow from bypassing the radiator in place? Do you have a fan shroud?

 

[mcditalia]

The radiator shroud is in place and it's fully intact . I'm not sure what the rubber sponge seals are or where they go. Any good places to have the clutch rebuilt?

http://i47.tinypic.com/34q9zsi.jpg

 

[Rex S]

There was a company that used to advertize in Hemmings that rebuilt fan clutches. I havn't bought a Hemmings for quite a while so don't know if they are still around. I did a Google search and they don't come up but some of the old shops still don't use the web.

 

[JohnZ]

I replaced my radiator with a correct repro from dewitts radiators.

The fan clutch assembly got tighter when it cooled down. Should it have zero play when hot and cold? The clutch is correctly dated. Where can I get a rebuild and how much will it cost?

It should work just the opposite - relatively free when cold, and tightened up when hot.

If the clutch is original, Fred Oliva can rebuild it, although he's always backed-up about six months. Otherwise order the GM #3916141 clutch from GMPartsDirect.com (about $150) which is almost identical to the original Eaton clutch.

 

[geekinavette]

I sense some confusion with terminology here....with "play" and "engagement" being mixed up. As has been said, there should be NO "play" in the fan clutch...as in no wobbling of the fan, at all. That is not the same thing as the clutch engaging/disengaging the fan.

This type of clutch can ONLY fully disengage the fan when the engine is running. When the clutch is not spinning the fan will always be "engaged"...but these clutches do not engage the fan 100% (whether running or not), it'll just feel resistant to rotating when trying to spin it by hand. When the engine is stopped, it just depends on what the temperature was when it was stopped as to how long the fan will spin. If the temperature was high enough to have the fan engaged, then it won't spin much at all...conversely if the temperature was not hot enough to have the fan engaged then it will spin until the silicone fluid "drains" (internally) enough to re-engage the clutch.

There are various levels of engagement, like a standard duty thermal clutch (typically for non-AC applications) that claims to spin the fan at something like 70% of engine speed. Then there is the heavy duty clutch (for AC equipped applications) that claims to spin the fan at something like 90% of engine speed. If you were to spin the shaft of these two clutches side by side, you'd feel more resistance with the heavy duty than the standard duty.

Just remember, the "default" state for these clutches is engaged. It will ONLY dis-engage once the engine is running. To observe this...start the engine up cold and rev it up some, you can hear the fan dis-engage after a few seconds. Or, if you were to start the engine up cold and start driving...usually you can hear the fan pulling lots of air for a few seconds, then that sound goes away as the clutch dis-engages the fan.

Another thing to note..."dis-engaged" is not 100% either. Typically this condition has the fan spinning at something like 20-30% of the engine speed.

There are some good descriptions of how these work on Hayden's site:

Hayden - Fan Clutches and Fan Blades

 

[mcditalia]

Thanks for the responses.

Good info from everybody, but thats why I come to this web site.

Johnz do you have Oliva's contact info?

 

[JohnZ]

Thanks for the responses.

Good info from everybody, but thats why I come to this web site.

Johnz do you have Oliva's contact info?

Fred can be reached at (954) 755-1161. Another fan clutch rebuilder is Vinny at Pampered Corvettes, (352) 799-8613.

 

[mcditalia]

A quick update on the problem. I bough an aftermarket fan clutch from autozone. Torqflo i believe, swapped out the units until I can get the original rebuilt. No difference. Took the car to a show yesterday and ran 220-230plus while trying to park it. Oddly enough I spoke to a gentleman who had a 63 fuelie and he said his ran the same way. Both of us had new radiators, good fan shrouds etc. He was considering retarding the timing. I am thinking of adding a "water wetter", but the same gentleman said it didn't do anything for him. It has been unusually hot here in the east coast, but believe the car should be running cooler than it is.

 

[Vetsvette2002]

Have you verified those coolant temps with an IR gun at the thermostat neck?
You do know that the 160* thermostat only controls the lowest opening temp and not the normal operating temp don't you? Once the T'stat has opened the engine's temp will continue to rise until stabilized.

Don

 

[JohnZ]

A quick update on the problem. I bough an aftermarket fan clutch from autozone. Torqflo i believe, swapped out the units until I can get the original rebuilt. No difference. Took the car to a show yesterday and ran 220-230plus while trying to park it. Oddly enough I spoke to a gentleman who had a 63 fuelie and he said his ran the same way. Both of us had new radiators, good fan shrouds etc. He was considering retarding the timing. I am thinking of adding a "water wetter", but the same gentleman said it didn't do anything for him. It has been unusually hot here in the east coast, but believe the car should be running cooler than it is.

I think you may have a gauge accuracy problem, not a cooling problem; don't spend another dime on it until you compare an I.R. gun shot of the upper radiator hose just above the thermostat housing against the gauge reading at the same time so you know what the gauge is really telling you. That appears to be a DeWitt's reproduction aluminum radiator in your photo, and that's the best one out there.

Tell your friend with the '63 fuelie not even to THINK about retarding the timing - that just makes idle and traffic cooling worse. '63 fuelies had a one-year-only design anomaly anyway (corrected for '64) - the distributor vacuum advance was connected to a "ported" vacuum source instead of to a full manifold vacuum source. Takes less than a minute to change it, makes a BIG difference.

 

[mcditalia]

I will get a hold of an IR gun to test the gauge problem.

A couple of side notes. The replacement fan clutch seems to have less "resistance" than the original one. That is when hot, it keeps spinning a lot more revolutions than the original when the car is shut off. And I mean a lot more.

I dont have the bipass hooked up. The freeze plug is stuck in the manifold and was never able to take it out. Can this negatively effect the cycling effect of the thermostat?

My idle tends to be close to correct when cold around 750 but drops when hot to 550 or so, which would drop fan revolutions. How much of a factor would this have on temp?

I will see the gentleman this weekend in Asbury Park for another show and talk to him about not retarding the timing. Interesngly enough, we talked about the vacuum advance, but can't remember if he changed the set up or not. I'll ask him.

 

[JohnZ]

A couple of side notes. The replacement fan clutch seems to have less "resistance" than the original one. That is when hot, it keeps spinning a lot more revolutions than the original when the car is shut off. And I mean a lot more.

I dont have the bipass hooked up. The freeze plug is stuck in the manifold and was never able to take it out. Can this negatively effect the cycling effect of the thermostat?

My idle tends to be close to correct when cold around 750 but drops when hot to 550 or so, which would drop fan revolutions. How much of a factor would this have on temp?

Most parts-store replacement fan clutches aren't thermostatically-controlled; they're only rpm-sensitive. The GM #3916141 Eaton clutch is as close as you can come to the original Eaton clutch; GMPartsDirect.com has them.

Not having the external bypass connected isn't an issue - it still has the internal bypass in the passenger side leg of the water pump.

550 rpm is way low for a 327/350hp idle setting; 750-800 will give a much more stable idle. Check your mechanical tach reading against an electronic tach reading at the same time (your dwell meter should have one).

 

[Jack Rossetti]

I thought I had a problem with my 64 327/365 motor. It was running at 210 to 220 degrees. It has a new radiator, 180 therm., 50/50 coolant, clutch fan but there was not difference. I then used a IR gun to take temperature reading of the goose neck and radiator hoses. I quickly realized that the sending unit was bad. A new sending unit cost $5. and 10 minutes to change it out, my temp. guage now reads 185 degrees on the hottest days .
Hope this works for you!!