Squeak from my Fan/Alternator Belt?

[OsoMoore]

I've had a squeak that occasionally appears, usually when I'm on or coming off the clutch. It has usually been a short 1-2 second squeak.
I first noticed it when accelerating out of tool booths from a rolling stop in 2nd (I know...).

I have it occasionally when I'm starting from a full stop in 1st, as I let out on the clutch. This happens about once a day.

I started the car on Tuesday, clutch in, shift to first, revved the engine a little, and it did it then with the clutch still out.

I wasn't sure if it was some sort of bearing or something else, but this morning I think I've figured it out. I started the car (cold morning start) with the blower fan on, and it squeaked immediately. I didn't have the clutch in, and it wasn't in gear. The squeak lasted for about 4 seconds. I think this indicates it probably is the fan belt. The belt is "new" as of about 3K miles ago.

What is a good way to make sure? Could I put some belt compound on and see if the squeak stays gone? I don't expect that to be a permanent fix, but if belt compound eliminates the squeak then at least I'll know the culprit.

[Canada Kev]

Belt tight enough? Sure it's your fan belt?

[brads911sc]

only do it when not up to operating temps?

[OsoMoore]

It has done it when very warm (slowing down for toll both iPass after 3 hours on the highway) as well as when cold, like this morning. It only seems to do it when I am slowed or stopped.

[OsoMoore]

I got my rear blower motor going yesterday by replacing a fuse. I tested it and worked last night. However my test was to turn the ignition to ON, but I did not actually start the car.

This morning I started the car and tried pulling the levers to turn the motor on. My squeal started right up! For now the blower is turned back off (and I hope I didn't blow the fuse again). The blower load causing the squeal seems to indicate that my squeal problem is the belt - right?

[Christien]

Just a thought, a shot in the dark, really - is it possible one (or more) of the fan blades is slightly scraping the shroud? That might explain why the noise increases when you start the blower (by blower I'm assuming you mean a/c - I don't have a/c, so not overly familiar with the parts). I'm thinking the added lateral tension might be bringing the blades into contact with the shroud. I had some scraping once, and it could be mistaken for belt squeal. Easy to check - just spin the fan by hand and look for marks.

[86 911 Targa]

pm sent.

[Porchcar guy]

The A/C compressor runs off the pulley system...the blower in the upper left side of the engine does not. If you were working the heat levers, then you probably have a blower motor that is making the noise. An intermittant squeal could be the belt tension.

[OsoMoore]

I have no AC - this is the heat blower motor. I ran the blower motor yesterday with the ignition on and car engine stopped, and the heat blower motor ran fine without any scraping noise.

[porwolf]

The same thing happened to me after I replaced my 30-year old original one. The belt seems tight but could possibly tighter. I am kind of reluctant to over tighten the belt because I had excellent results with looser than recomended belts in my 82 Landcruiser. I lost a water pump, smog pump, power steering pump due to shot bearings when the belts were tight according to specs. Then I kept them as lose as possible, even with an occasional squeal. No more proplems with those componennts. It make sense to me that too tright belts are an enormeous load on the bearings. Cold it be that my new Porsche belt is stiffer than the original one. I will try pelt spray from an auto parts supply store next. I figure that can't hurt.

[OsoMoore]

I did some more checking, and the blower is still working fine, although I'm not running it while driving because of the belt slippage.
My speculation is that, because this belt is relatively new, it has simply stretched a little and I need to tighten it.

Time to pull out my 101 Projects!

[Grady Clay]

We may have some confusion about parts.
Your ’79 (if original) has an air pump to the left of the fan. It is belt driven off a second part of the outer pulley half on the fan. A fuse would not affect this pump.

You also have (if original) an electric fan for the heater mounted just left of the CIS and to the front of the car from the air pump. This electric fan does have a fuse.

Please post an image of your engine.


Intermittent (occasionally temperature sensitive) ‘squeaks’ can be from a loose fan outer pulley half. Make sure there isn’t any ‘wobble’ to the outer pulley half.

If you have a dry (not sufficient lube) pilot bearing in the center of the flywheel, this can also give a ‘squeak’ when taking off from a stop.

Best,
Grady

[OsoMoore]

I got some video and relaunched the thread with that... maybe I should have just updated this one.
Bad Noise when engaging blower - fan belt slippage?
It shows the engine pretty well.

I'm down and out with my wisdom teeth removal yesterday... not all there.

[Flat Six]

Fan/alt belt completely separate from heater blower; any perceived relationship between the two is likely coincidental.

Grady's advice very sound; loose pulley outer half (sufficient belt tension and 6 total shims) is a potential culprit.

After watching your two YouTube videos, two things are clear to me: 1) your fan/alt belt is loose [as James Brown already pointed out], and 2) you need to block off the huge cooling air leak to the left of your fan housing.

Remember to clean both pulley halves of old/smeared belt material.

[OsoMoore]

Originally Posted by Flat Six

Fan/alt belt completely separate from heater blower; any perceived relationship between the two is likely coincidental.

Grady's advice very sound; loose pulley outer half (sufficient belt tension and 6 total shims) is a potential culprit.

After watching your two YouTube videos, two things are clear to me: 1) your fan/alt belt is loose [as James Brown already pointed out], and 2) you need to block off the huge cooling air leak to the left of your fan housing.

Remember to clean both pulley halves of old/smeared belt material.

Sounds like a plan. I've been reading threads on things to watch out for with the belt tightening/replacement. The huge cooling air leak is because I removed the hose to the blower in order to get a look at the blower - I shan't leave it that way

[Flat Six]

Originally Posted by OsoMoore

The huge cooling air leak is because I removed the hose to the blower in order to get a look at the blower - I shan't leave it that way

Good deal; would hate to see you overheat b/c of this!

[SCadaddle]

That blower fan in my 82 SC was completely shot. First clue something was wrong was that the squirrel cage fan part of the assembly wasn't centered in the housing. Once we removed the assembly and started tearing it down we realized the fan wasn't centering in the housing because the armature of the electric motor wasn't centering in the motor housing! So we take the motor apart and sure enough there are all kinds of parts---a C clip, a spring----stuck to the magnets inside the motor housing.
So we found another one and a few minutes later everything was back together and tested with test leads to a battery. Squirrel cage fan runs nice and true, electric motor sounds good. Put it back in the car and I've yet to try it due to other "pending" items.

So here are my thoughts: Your electric motor and fan are about to fail, and with the engine running it is putting a lateral (air) pressure load on the squirrel cage fan and that is what is making the noise. You could probably test this by removing the electric blower assembly and using test leads to a battery. You know it runs, but now shake it in your hand and tilt it in all different directions while it is running to see if it will make the same noise.

[OsoMoore]

Did some more work this morning!
I tightened the belt by one shim.

I also removed the hose from the engine fan to the blower. This eliminates lateral air flow through the blower as a possible culprit in the creation of bad noise. However the bad noise continues.

To recap:
1) Blower fan sounds fine running without the engine running.
2) Engine fan belt is now tightened.
3) When blower fan is engaged while engine is running, there is a loud vibrating squealing noise.

I have a voltage meter in the car, and voltage drops from 14v to 12.5v when I engage the blower and the squealing starts. RPMs drop as well.

You can see/hear the noises here:
SC Blower without Engine - YouTube
SC Blower with Engine - YouTube
The noise is a little higher-pitched since I tightened the fan belt.

The blower fan has about 3.3 ohms resistance, so its pulling ~4 amps. I don't know if that's high or not, but maybe it is. I do want strong working heat, and I commute in stop-and-go traffic, so I'd really like to have a working blower. But I don't want to buy a new blower fan and discover that wasn't the actual problem.

I'm not sure where to go from here. Thoughts are appreciated!

[OsoMoore]

I removed the blower motor and ran it off of the battery directly. It seems that the issue really is only the blower motor - it makes noise pretty much erratically, regardless of whether the engine is running or not. Now I just need to decide if I want to backdate heat, repair/replace the blower fan, or come up with my own rig.

[86 911 Targa]

Originally Posted by OsoMoore

I removed the blower motor and ran it off of the battery directly. It seems that the issue really is only the blower motor - it makes noise pretty much erratically, regardless of whether the engine is running or not. Now I just need to decide if I want to backdate heat, repair/replace the blower fan, or come up with my own rig.

I'm not familiar with your M/Y, but if you have a fan duct like the '86,
check the mounting bolts.

Also, all A/C bracket bolts including the bracket mounting bolts to the engine block.

A loose A/C engine bracket can introduce vibrations into your ducting, it did it to ours.

Good luck,

Gerry