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Inescapable Belt Squeal - fan clutch going out...?
Here's a brief overview: On my way home from a recent road trip (500+ miles) I ran into an issue with my belts squealing. They were brand new only a few days before but even with them tightened properly, I could not get the belts to stop making noise. Eventually I figured out that it would squeal anytime the fan clutch was engaged above 3k rpm, which seems plausible, although the fan clutch appears to be working correctly. It also occasionally squeaks between shifts when doing a wot run. The engine is setup with a stock 1980 clutch fan, no air pump, and an S6 alternator with a banzai dual belt pulley.
I did some looking through old threads and it would seem my fan clutch is acting as it should:
- spins freely when cool and the engine is off
- engages for a short time after the engine has been started
- engages when car has been idling in stop and go traffic
Here's what's confusing though. When cruising home for three hours at ~70mph in sunny 70-80F degree weather, the fan clutch would every once in a while engage and of course I would start hearing the belt squeal again. This was on the interstate and flat level ground, no changes in load or anything obvious would cause the clutch to engage. One thing to consider though, is that my t-stat was stuck slightly closed and temps were a little higher than normal - this has since been fixed. The belt would also only squeak above 3k, and then once the fan disengaged all would be well. Today driving around in sunny 75F weather the fan would also engage at every stop light, after which the belts would squeal in first and second above 3k, and finally by sometime in 3rd gear it would disengage and all would go back to normal. Does this sound like normal fan clutch behaviour? I am inclined to say yes.
My car has also has a not so friendly relationship with belts. In the past this has mostly been thanks to my alternator pulley - it was not straight and would wear belts fast and unevenly (outside belt always ended up longer). That was remedied shortly before the trip, and now both belts are wearing equally. However, now that the pulley is straight I am noticing that the back side of the belts is wearing faster than the front and I'm guessing that the alternator pulley is a little too far out. Soon I'm planning on having my alternator rebuilt (it has its own set of issues), and at the same time I would like to have the alignment of my pulleys checked as that's not something I believe I can do accurately.
I've also noticed that the belt closest to the engine seems to waver slightly when viewing the alt pulley. By this I mean that when looking side on at the top face of the belt, it appears to be tilting back and forth. Perhaps I just got some bad belts?
That was a good hunk of (not particularly organized) back story so to wrap things up here:
- Does the fan clutch appear to be behaving normally? Are there any other tests I should do to confirm this?
- What are the odds that new but worn belts are the primary cause of the squeaking? I'm figuring that this is the issue; mostly curious if there's other things that might be awry.
From what I've seen on this forum, without the factory air pump you may need a gilmer drive to quell the squeal. It's also worth taking a straight edge to check if your upgraded alt pulley is in line with the other pulleys.
You don't want gilmer pulleys, they are noisy and add extra wear to the engine because of the way they mount on the eshaft. Based on your observations I would suspect a belt or the pulley. Its hard to find 2 belts exactly the same size. Sometimes you have to buy 3 or 4 and match em up. If you see wobbling then I would suspect pulley not being true on one of the faces the belt seats on. I would say your fan may have an issue if you think its engaging while cruising at that speed but how do you really know that? I would start with pulley trueness and alignement, then belts, then worry about the fan. Try it with one belt (the one that doesn't wobble) and see if theres a difference.
I honestly haven't seen much info on people using gilmer belt systems on these cars, but I guess it's always a possibility. For now I'd like to avoid that if possible, though.
I get what you mean about finding two belts the same length, although it always seems to me that they will stretch out to pretty close to the same size once they've been run a while (as long as they were close in the first place). This was the first time I've ordered belts on RA though, and for whatever reason they look a little worse quality than ones you can find in local stores. For example, both belts have some degree of a groove/indent near the center of the top face which is something I have not seen before. They also looked (when new) as though they perhaps hadn't been cut properly and also more cord than what would seem normal was protruding from one side. I could very well be crazy, but they just didn't look as good as belts of the same brand that I've bought in person. Of course because it was RA I paid far less, however maybe there's a good reason for that...
The idea that a groove on the pulley isn't straight has come to mind before and is a little concerning. I've had the setup for a while now and, as I mentioned before, recently discovered that the pulley was not true. A local alternator guy fixed that, but perhaps if the pulley itself was not true, the groove may not be also. Bothers me a little that a $45 pulley from Banzai Racing could have been machined flawed (probably just a one off mistake, but still). I'm planning on taking it back to the same guy that corrected the pulley the first time and also have him check over the pulley alignment and correct it if need be, as well as rebuild the alternator. After the pulleys are sorted I'll move onto belts as you said t_g_farrell.
Regarding the fan, I can tell it's engaged because, well, I can hear it. Cruising below 40 mph it's pretty easy to hear when engaged and even above that I can still usually hear it. Now, on the highway I of course cannot hear it, but I can hear the belts begin to squeal every time it would stay engaged over 3k rpm. Yesterday it was mid 80's to high 90's and the fan would stay engaged a good portion of the time driving. Certainly every after every stop, and then sometimes (particularly towards the end of the drive) it would stay engaged even while cruising for a while at 30-40 mph. If I was moving long enough it would usually disengage, but it sure took a while sometimes. Engine temps are also solid now that I've replaced the t-stat, so I don't think it's an issue with the car running hot.
Until I can get some of the pulley and belt issues sorted out, my main question would be this. If the fan is engaged above 3k rpm, should a car set up with a dual v-belt system be capable of not squealing in that scenario?
I honestly haven't seen much info on people using gilmer belt systems on these cars, but I guess it's always a possibility. For now I'd like to avoid that if possible, though.
I get what you mean about finding two belts the same length, although it always seems to me that they will stretch out to pretty close to the same size once they've been run a while (as long as they were close in the first place). This was the first time I've ordered belts on RA though, and for whatever reason they look a little worse quality than ones you can find in local stores. For example, both belts have some degree of a groove/indent near the center of the top face which is something I have not seen before. They also looked (when new) as though they perhaps hadn't been cut properly and also more cord than what would seem normal was protruding from one side. I could very well be crazy, but they just didn't look as good as belts of the same brand that I've bought in person. Of course because it was RA I paid far less, however maybe there's a good reason for that...
The idea that a groove on the pulley isn't straight has come to mind before and is a little concerning. I've had the setup for a while now and, as I mentioned before, recently discovered that the pulley was not true. A local alternator guy fixed that, but perhaps if the pulley itself was not true, the groove may not be also. Bothers me a little that a $45 pulley from Banzai Racing could have been machined flawed (probably just a one off mistake, but still). I'm planning on taking it back to the same guy that corrected the pulley the first time and also have him check over the pulley alignment and correct it if need be, as well as rebuild the alternator. After the pulleys are sorted I'll move onto belts as you said t_g_farrell.
Regarding the fan, I can tell it's engaged because, well, I can hear it. Cruising below 40 mph it's pretty easy to hear when engaged and even above that I can still usually hear it. Now, on the highway I of course cannot hear it, but I can hear the belts begin to squeal every time it would stay engaged over 3k rpm. Yesterday it was mid 80's to high 90's and the fan would stay engaged a good portion of the time driving. Certainly every after every stop, and then sometimes (particularly towards the end of the drive) it would stay engaged even while cruising for a while at 30-40 mph. If I was moving long enough it would usually disengage, but it sure took a while sometimes. Engine temps are also solid now that I've replaced the t-stat, so I don't think it's an issue with the car running hot.
Until I can get some of the pulley and belt issues sorted out, my main question would be this. If the fan is engaged above 3k rpm, should a car set up with a dual v-belt system be capable of not squealing in that scenario?
Thanks again for the ideas thus far.
You fan shouldn't be engaging, its should stay cool enough with the air flowing through the engine bay at cruising speed to not need to be on at all. I know this is true because my electric fans turnoff when I go into 4th or 5th gear, otherwise the are on all the time. In 2nd/3rd gear with the fans on the car will actually not cool as well because they aren't helping. I know I should use a thermal switch but its dead simple right now. So if you fan engages while curising it could cause poor cooling over time.I bet your fan is about to go bye-bye.
I have had similar problems with the factory clutch fan setup with dual belts after an air pump delete.. and of course not wanting to over tension.
Your clutch fan behavior sounds a little similar to mine, in the sense that I think it is engaged more than it should be, and especially around the city it is all i can hear sometimes.
I have a 3 row 'OEM' type rad, new OEM t-stat, etc. So all parts are in great condition and my coolant temps measured from the fitting on the back of the water temp housing are never hot.
I decided to go with a side mount alternator setup... 20% of the reason to run a more ideal dual belt setup, and the other 80% to clean up the engine bay.
I am still looking for a new clutch fan. The local dealer wants $500 for a new one....
I'm running dual belt (RB underdrive) with factory fan clutch and fan and never hear belt squeal, even in 110F+ temps. If your fan is engaging at speed, there's a problem with your cooling system and it should be gone through: new thermostat, fresh coolant, new radiator cap, and a flush and rod-out wouldn't hurt. Point being, your fan clutch is behaving as expected - it engages when the air coming through the radiator and hitting it is hot. When it engages, it causes additional drag on the belts which is what's causing your squeal.
On a properly functioning cooling system, it will flow plenty of air above about 30mph that you don't even need a fan installed. In fact, that little rubber flapper door on the lower left corner of the fan shroud is to allow air to exit at speed because the air coming in the front is CONSTRICTED by the fan, and it's spinning!
Have you tried any belt dressing? It shouldn't be needed with good quality belts, but worth a shot - and if it works, maybe you just need new belts...
Well it's beginning to sound like the fan clutch might be on it's way out. Something else I've noticed today (temps around 100F) is that at idle, the fan practically never engages. While I'm actually stopped I essentially never hear it, even if it was engaged as the engine was idling down (in other words it disengaged at idle/car not moving). It also kicked on for a while on the highway today cruising at 60 or so (temps were indicating normal), and based on what y'all have said that sure doesn't seem right.
I should reiterate that coolant temps are showing normal - based on the stock gauge that is, which over the last couple years has proven to be rather dependable. I also sometimes check the keg temp with an infrared thermometer and the top (like where the rats nest would normally be) is around 190 on hot days like this, which seems reasonable to me...? Not even a couple days ago I replaced the t-stat with an OEM part and drained/replaced the fluid. Doing so solved my inconsistent running hot issues (t-stat was sticky). I've also replaced the radiator cap, hoses, and most recently the radiator with an eBay 3-row aluminum one which seems to be doing the job better than expected. That all said, I'm going to guess that my cooling system (sans fan) is not the main issue, or perhaps even one at all. I should also mention that this is an SA, so we're talking short style rad and the shroud does not have a rubber flap.
In theory I have one more operational clutch fan in storage, although it's an FB style which means I need to find the matching water pump stand-off. Hopefully that will do the trick, and if it doesn't.... well maybe I shouldn't have sold my other clutch for only $20. Oh well, water under the bridge.
And no, I haven't tried belt dressing, I'll look into that. Thanks for the idea. I've got a feeling that it will work, indicating (like you said) that my belts will need to be replaced anyway - squealing their way across a whole state surely didn't do them any favors. I'm also inclined to say it's at least partially a belt issue, because when rev matching the belts squeal momentarily as well, even if the fan clutch isn't engaged. I find this all rather amusing too, because it used to be that my belts would squeak a little at idle (squeaking on the alt pulley), but anything above that was fine. Then I got the pulley machined straight and bought new belts and this whole debacle occurs. These belts also stretched a lot. As in, driving 300 or so miles I had to keep pulling over to tighten them because they just got so loose so darn quick. And given that I have the Banzai Racing alternator adjuster, I seriously doubt the alt could have just been sliding down due to improper fastener tightening. Eh, strange potential combination of issues, that's for sure.
Gates, Bando belts and most other quality brands break in rapidly - like in the first 10-15min of running, and then do not stretch beyond that. That's why Mazda FSM shows different tightening specs for new vs. re-use of old belts. The belts, once broken in don't tend to stretch further, so if you're required constant tightening, you have bad belts.
Go with a quality brand next time; it's not worth the few bucks you save for all this hassle and concern. Could still be the fan clutch, as you think - but belts are cheaper, faster, and easier to rule out, and you already know you need to replace them,...
The belts are actually Gates brand (or at least they say they are...) which I have used in the past with success, although they never before required tightening like this pair did. I definitely agree that belts are part of the issue, but the fact that my fan clutch seems a little "engage-happy" makes me curious.
Over the last couple hours I've been going through my parts storage looking for the water pump -> fan adapters for the FB bolt pattern fan clutches. I could've sworn that S2 cars used an aluminum standoff like what would be found in S1 vehicles, but all I could find was two of what I think are the S3 shorty adapters (I'll include pictures below). Of course they will fit, but they'd also pull the fan back towards the engine, unless the later fans have a longer shaft/thicker mount on the clutch assembly itself (I haven't checked that, but it does sound familiar now that I say it). With the S1/S2 style radiator shrouds that would mean the fan is actually behind it, not within it. Perhaps that would be an issue, maybe not. I assume it will be less effective regardless... although with the 3-row radiator the shroud is pushed towards the engine a little anyway, so maybe it wouldn't be so bad after all? Eh, enough speculation, I'll get it installed and see how it looks.
Anyway, if someone could help me recall what different styles of water pump -> fan adapters there were I'd appreciate it. For the time being I'll probably throw on the short steel adapter and an FB fan to see if that changes much clutch engagement-wise; I expect the belt squeal is just it's own issue. To wrap this up here's a photo of both my current SA (S1) adapter and one of the short steel adapters I found.
Edit: I should have mentioned that I'll be dropping off the car tomorrow to have the alternator rebuilt and the alternator pulley checked for proper alignment. I bet they'll have a fun time trying to start the car if it sits overnight
Last edited by Benjamin4456; 07-28-20 at 06:23 PM.
The S3 uses to aluminum big fan spacer and the S1 the short metal one.
Really? Well that's interesting, I could've sworn it was the other way around. The extra fans I have are off of an 82 and an 83, and both will match the short metal spacer, while only my current fan on the SA fits the aluminum one. Then again my SA has had an interesting life in terms of engine swaps and whatnot so... perhaps my references are not accurate. I also thought that the later series shrouds were deeper, which could explain the shorter spacer. Hmm, interesting.
When refreshing my engines, I like to swap to the 2nd gen (1986-1988) aluminum water pump housing and water pump. I used the aluminum big spacer that came on my 1985.
Well I got a new fan/clutch installed and so far it seems like it's solved the unnecessary engagement issues. Then again it isn't quite as hot as it was before, so we won't really know until I can test it again in some heat. The spacing relative to the shroud also seems fine; not as far back as I would have thought due to the thicker clutch flange.
I've also noticed a couple new things with this clutch. For one, when starting the car it stays engaged longer than my old one, and then when it finally goes to disengage it does so more slowly. It also doesn't seem quite as quiet when increasing rpm as my old one, although it's definitely not fully locked up because on start up you can hear what that sounds like. Perhaps it's the different blade design (I noticed this style fan has seven irregularly spaced "straight" blades, as opposed to my previous eight "curved" blades), or that it's not disengaging quite all the way which makes the different sound. This new fan also has a larger clutch assembly which I hadn't noticed before.
Anyway, it works fine on the highway - no squealing due to improper fan engagement - so that's a good sign. I just dropped off the car to have the pulleys checked and the alt rebuilt, so after that I'll see to some new belts and find out if that solves the last of the squeaking during high rpm shifting. Thanks for the help thus far.
07-26-20, 12:01 AM
