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Fan Clutch Problems

24K views 27 replies 8 participants last post by  Classix_Lover 
#1 ·
Bought a standard thermostatic fan clutch setup from summit quite a few months ago and it's been sitting for some time. Finally got around to installing it with an OEM fan. Whenever it engages, it's supposed to run at 70% of the engine's rotational speed. I tested it without a shroud first to see if everything was working properly and what a surprise, I don't think it is. I took it around the block for a good 20 minutes, parked the el camino in the garage and let it idle for a good while. Shut it off, grabbed a fan blade and attempted to turn it and.. what the hell? The fan's turning relatively freely, not resisting being turned like what it's supposed to do when engaged. Cranked it up again, let it get to 220 and then shut it off. Again, still offering very little resistance. This is a load of bull. Defective part or is this really what it's supposed to be doing? The fan is no more than 1" away so it's plenty close to absorb the heat properly. I'm guessing it's a defective part. I don't want to go through the trouble of sending it back to summit and have it go through warranty check and wait for god knows how long just to get another one that might be defective as well. I'm not very happy but at least I fixed the leak from my radiator.
 
#2 ·
A thermostatic fan clutch drives when the air temperature through the radiator exceeds the thermostat setting of the clutch.

220* coolant temp is too high.

Where did you read 70% ?
A fan clutch will totally lock up when engaged.
It disengages by temperature and high rpm.

I have gotten the best service from Imperial brand.

I also don't like HD rated clutches, as they don't disengage by rpm until a higher range, and become audible in the vehicle at 40-50 mph when you shouldn't need a fan anyway above 30.

I made a mistake once and installed a HD one on my "TownCar" (high gear w/OD) and at 100+ ambient it hummed until 78 mph. :nono: Took it back and got a standard duty.
 
#3 ·
Well I asked them what operating temperature the clutch is supposed to engage at and they didn't know... lol shows how smart they are when temperature is a critical factor for correct operation. I asked them before what the difference was between a standard and heavy duty clutch and they told me while it's engaged, it's at 70% of the engine's speed while the heavy duty one is at 90%. Sounded a bit odd to me but it is summit technical service after all. What would the difference be if this isn't correct information? Yes I do have the thermostatic operated one since there is a wound coil spring on the front of the clutch. I don't want the non-thermostatic operated ones for your specific reason of it still engaging and making alot of racket at a normal cruise speed where you wouldn't need it's cooling abilities.
 
#4 ·
Regardless of rhetoric,
I guess it is simple to say that the one you have is bad for your installation.
I would suggest buying an Imperial locally, and then sending the other one back.

At least if it does not work correctly, you can take it back easily.
 
#5 ·
I was thinking of doing that. It is a flex a lite brand clutch after all so somehow, this doesn't surprise me. Will somewhere like O'Rielly's have these fan clutches or where would I find these locally? What is the real difference between standard and heavy-duty clutches? Does the heavy-duty clutch engage at a lower temperature than the standard one?
 
#6 ·
Classix_Lover said:
I was thinking of doing that. It is a flex a lite brand clutch after all so somehow, this doesn't surprise me. Will somewhere like O'Rielly's have these fan clutches or where would I find these locally? What is the real difference between standard and heavy-duty clutches? Does the heavy-duty clutch engage at a lower temperature than the standard one?
To the best of my knowledge the HD have a heavier body with deeper fins, and stay engaged to higher rpms. I cannot verify if they engage at lower temps. Mostly these are found on towing vehicles that might be doing higher rpms in lower gears going up hills and need extra rpm engagement for cooling.

I do know that persons with very heavy duty factory fans have installed the standard clutches and the vehicle ran hot. Maybe the fans were too much for the clutch, maybe the clutches were bad. ??

I don't know which stores carry which brands. You might go online and get a part number and then make some calls to see if they have it in stock.
 
#7 ·
Well I have a mild 454 so I figured a standard duty clutch with a good fan shroud should suffice, but then again it does get pretty hot around here in the summer. I'm guessing I should try the SD one first from somewhere locally, although I'm not sure where to find one around here.
 
#9 ·
Classix_Lover said:
Well I have a mild 454 so I figured a standard duty clutch with a good fan shroud should suffice, but then again it does get pretty hot around here in the summer. I'm guessing I should try the SD one first from somewhere locally, although I'm not sure where to find one around here.
I have had my tow vehicle 80 gmc dually crew cab and have battled running hot while towing for 17 years, changed everything, water pump, rebuilt motor, radiator, sealed shroud, dist new with correct timing. was told the fan clutch was ok, You will not be disappointed if you buy the GM your only choice for the best clutch fan for your big block, more expensive but my over heating problems are over. There is a sufferance in clutch fans. the neighbor spent over $700 dollars on rad and electric fans for his motorhome no good till he took all the stuff of and when with the GM heavy clutch fan. Don't be cheap like I am and was it cause me great frustration. Hot engine equals hotter transmission and other problems. trust me Ed ke6bnl
 
#10 · (Edited)
Guy Hiltz said:
You could also go to your local GM dealer and get one,ask for one that fits a big block pick up truck,thats what I put on mine and it works just fine.
Yea and fork over at least $200 lol.

Ed, I don't think dealership items are my only option for quality. Plenty of aftermarket suppliers offer quality items, I just had a swing and a miss with that particular brand. I'm not exactly trying to blow all my spending money on dealership items.

After I get off from my boring classes, I'm going to go to Pep Boys and ask for an Imperial brand clutch. It was a pain in the *** bolting up the fan though since I hardly had any clearence to turn the bolts in. That's why I'm mainly disappointed in the clutch being defective knowing that I have to start all over again.

Anybody know if Visteon is a good brand? Looked up Pep Boys products and found that they carry those type of fan clutches. Hopefully you all can reply within an hour since I'm heading over there after school and I'll check here before I go.
 
#11 ·
xntrik said:
A thermostatic fan clutch drives when the air temperature through the radiator exceeds the thermostat setting of the clutch.

220* coolant temp is too high.

A fan clutch will totally lock up when engaged.
It disengages by temperature and high rpm.

I also don't like HD rated clutches, as they don't disengage by rpm until a higher range, and become audible in the vehicle at 40-50 mph when you shouldn't need a fan anyway above 30.

I made a mistake once and installed a HD one on my "TownCar" (high gear w/OD) and at 100+ ambient it hummed until 78 mph. :nono: Took it back and got a standard duty.
I agree completely. I have an HD on my 454 and it locks up at all the wrong times. Its much more viscous so it spins exceptionally strong when its coldest... exactly when you DON'T need it. The coolant has actually never made it to a temp where the fan has locked up.

I also think that its quite possible that your idling experiment isn't a very accurate test. Getting that airflow moving is the key. At idle there might not be enough air moving over the clutch to heat it up. The coolant might be 220, but its possible that the clutch only sees 190. I might let it idle until its really hot, then drive it.

But, its kinda a moot point... I suggest getting a standard clutch.
 
#12 · (Edited)
Ok, here's the deal. Got another fan clutch, heavy duty this time, Hayden brand. Took off the old one despite some troubles with the bolts snapping, fixed it, got the right sized bolts, American fine thread, not metric, hence why they broke; I was impatient getting the other one on and didn't double check to see if the threads were truly the right size. They were slighhhttlyyy different but enough to have it bind up and snap on me. :drunk: Reinstalled the fan setup, ran it, everything spun true and of course massive cooling improvement at higher speeds compared to the other mediocre electric fans. Once again, let it idle for a good while. Shut it off and imediately grabbed the fan blades to spin it and whaddya knowwww! The damn thing is STILL freewheeling and not properly locking up. What is the chance of me getting 2 defective parts?? Something is not right here, the fan clutch is so ridiculously close to the radiator and it should be absorbing the heat, there's no question about that. It's getting plenty of heat absorbtion yet still freewheeling. Thoughts? Should I try a third time and return this one for another one?
 

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#14 · (Edited)
Classix_Lover said:
I beg to differ

"Turns the fan 80%-90% when engaged"

60-70 for standard duty.

http://haydenauto.com/pdf/hayden/fan-clutches/fan-clutches.pdf

Scroll down and you'll see.
Thanks for that link.

65% seems insufficient. In fact, 80% doesn't sound that good... :drunk:

added= I have searched the net again and your link is the only place I have ever seen tech specs.

Thanks again for that information. :thumbup:
 
#15 ·
xntrik said:
Thanks for that link.

65% seems insufficient. In fact, 80% doesn't sound that good... :drunk:
So what's going on? Is this really working correctly? I don't believe that it is. I noticed no difference in the free wheeling speed compared to before the heated test. What do you think I should do? Third times the charm right? Lol :drunk: It's supposed to engage at 170* radiator air temperature, I let it get up to a bit over 210.
 
#17 ·
I'm doing something a little different for testing the clutch. I'm baking it at 210* in the oven for a nice good while to see if there is any noticeable difference in resistance to being turned. I was aware though about the engaging % diminishing over time. Good link though, thanks.
 
#18 ·
Classix_Lover said:
I'm doing something a little different for testing the clutch. I'm baking it at 210* in the oven for a nice good while to see if there is any noticeable difference in resistance to being turned. I was aware though about the engaging % diminishing over time. Good link though, thanks.
All it takes is a good "turkey" baking thermometer..... might be one in that kitchen drawer.
 
#20 ·
As I talk more with my dad about this and think about it more, I don't know if it's physically possible to actually tell the spin difference just by grabbing on to the clutch and turning it by hand. I feel that centrifugal forces are necessary in order to see/hear it engage at higher speeds. Chances are, I just need to add a shroud but the main reason I've been wanting to see if it engages properly is so that I don't have to go through all the trouble of removing my shroud to replace a defective clutch. I guess I'll hang onto this for now, fabricate a shroud, and see where it goes from there. Anyway xntrik, I guess this thread is a good way to show people how to diagnose and test their clutches for problems. Thanks for the help all who contributed. Next step is shaving off a bit of the ends of the clutch fins to help it go in easier without scraping up my radiator. Had a hard time slipping the clutch out.
 
#21 ·
Fan

My 1970 GTO would run hot without the shroud even with a flex fan and it being one inch from radiator so I placed the shroud back and it was alright im going to see if this guy close to my house has an extra one I live right down the road from you off of FM-528 also how about using an electric fan that comes with a shroud you might want to check your timing as well.
 
#22 ·
I bought a cheapo haden at the local part store for less than 30.00. Standard duty for my BBC. Keeps my engine cool just fine and I live in south Texas.

Be careful which pilot shaft you get!!! 454 water pumps come in 1/2 inch or 5/8 shafts. You will have balance problems if you install a 5/8 shaft clutch on a 1/2 shaft water pump.
 
#24 ·
Another thing is to use the bypass hose and use the proper size hose (5/8's) and proper shape (pre-formed 90 degree). I recently had a 396 over heat when I didn't use the short bypass hose going from the water pump to the intake. I put the hose on and all the over heating problems went away.

For some reason, my 454 didn't need the bypass hose to run cool. But, I would put on a hoses if you aren't using one to see if that is the problem.
 
#25 ·
GMCTRUCKS said:
My 1970 GTO would run hot without the shroud even with a flex fan and it being one inch from radiator so I placed the shroud back and it was alright im going to see if this guy close to my house has an extra one I live right down the road from you off of FM-528 also how about using an electric fan that comes with a shroud you might want to check your timing as well.
Timing's just fine, I still need to fabricate the shroud. The main reason I was doing this test is to be sure the clutch was operating properly before I go through the trouble of fabbing up the shroud and just having to take everything apart if something wasn't operating correctly. Also, I did have a dual electric fan setup before but cooled inadequately; pos aftermarket thin fans, it's really no surprise why it likes to overheat at idle.
 
#26 ·
Will H said:
Get a hair dryer or a heat gun and heat the thermostatic spring on the front of the clutch and see what happens, I think that you will find that the clutches you have are working correctly.
I did bake the clutch at 210* for over 30 minutes and pour hot water on the spring last night. I did see the spring move ever so slightly, but to just turn it by hand to tell the difference isn't going to work. Centrifugal forces are a key factor for this I'm sure, hence needing higher rpms to really see if everything's working correctly. It was misleading having people tell you it's supposed to lock up completely and not freewheel whatsoever when it's engaged kinda threw me off at first but everything's alright now. I'll keep this thread updated once I get around to fabbing up a custom shroud.
 
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