have a bad bearing in the A/C pulley. The system works fine but has a wine that sounds like a blower or a gear drive cam.

The clutch is not dragging and the sound is roughly halfed when I turn on the A/C and at its worst when it is off. My thought is the bearing in the pulley spins all of the time and with the clutch pulled in it side loads the bearing to quite it down some. I can hear the noise when turning the pulley by hand.

I have looked up the procedure in the GM shop manual. The clutch plate has to be pulled with a special tool. Then another tool is used to lock into the center of the pulley and pull the pulley off of the compressor shaft.

They list another set of tools to install the bearing and stake it in place and finally another tool to reinstall the pulley on the compressor.

They say that this can be done on the car without opening the A/C system.

Prices for the parts:

Bearing: $20.00

Tools: Not sure

Compressor with shippping: (New GM) $350

Receiver Dryer: (New GM) $50

New Clutch Pulley assembly: $110

My questions:

1) Has anyone done this job, are the special tools needed and where do you get them?

2). Is a functional 90K miles A/C compressor ready to be replaced anyway?

3). What do you think would be the most cost effective way to proceed?

Thanks

Z28

make a friend in the service department at a dealership.. and then borrow his tools to just change the bearing

When the a/c clutch is disengaged, the outer part of the pulley is free-wheeling around the inner part, on a bearing. But when the clutch is engaged, that bearing is no longer rolling because the inner part starts turning too. So if it's still making the noise when the a/c is on, I think it's probably not that bearing.

If you have an idler pulley near it, it's probably changing the load on the idler pulley, and that's your most likely culprit. (easier to fix too)

A mechanics stethoscope should help you find which pulley exactly.

(or a length of garden hose or something similar...)

Just be careful not to get the hose caught up in a pulley or belt while you're checking around in there...

I just went through the same thing and it was not the A/C bearing it was the tensioner as John_D stated. Take the belt off and spin the pulleys by hand and see if they are making any noise. I bought the pulley assembly so if it is that I have one that I will sell at a discount.

"When the a/c clutch is disengaged, the outer part of the pulley is free-wheeling around the inner part, on a bearing. But when the clutch is engaged, that bearing is no longer rolling because the inner part starts turning too. So if it's still making the noise when the a/c is on, I think it's probably not that bearing."

I thought the same thing, but if you look at a parts break down you will see that the pulley bearing doesn't press on to the shaft, it presses on to the nose of the compressor body. The bearing is spinning at all times A/C engaged or not. The compressor shaft floats in the center and has the outer clutch plate pressed on to it. When you start the compressor the pulley is then clutched to the compressor shaft. But the whole time the bearing was doing the same thing, inside race on the compressor body and outside race pressed into the ID of the pulley. The compresor is likely to have an internal shaft bearing, but that is not the one that I think is bad.

The tensioner was what I hoped it was but I pulled the belt and spun the tensioner pulley, no sound at all. Turned the compressor pulley and I could hear the dragging sound.

Thanks for the comments and for thaking the time to post.

Z28

I spun the tensioner with the belt off, no sound. Spun the A/C pulley and I could hear the dragging sound.

What kind of clutch / pulley setup do you have? GM parts, Reman, Napa? How much?

Thanks for the post.

Z28

Where are you located? If you're near Dallas, TX, a friend of mine can fix that problem for you. He is a dealership tech & has the tools to fix it.

I am in southern missouri, so that most likely won't work.

Thanks for the suggestion.

Z28

I fleshed out my signature with mods and location.

That makes sense, now that you say it...

Otherwise that outer ring would just be floating, with nothing to support it.

Sorry for trying to steer you the wrong way. Maybe it was wishful thinking taking over.

I am not sure these guys have tools, down here in the sticks.

Population 2045, a big Hee-Haw salute!!!

No worries mate,

I knew what you were thinking because, I thought the same thing.

So I thought I will switch the A/C on and it will stop, no-go.

Then I had to go and ponder it some more.

Z28

It's a GM unit from gmpartsdirect.com. I just looked it up and came up with part #6580037 and a total price including shipping of $98.36. I'll verify the part number when I get home tonight. How about $60 including shipping via UPS ground.

If you would please check the P/N, I might be interested.

I still would not have the tools to pull or install the pulley. That is the bigest problem I am facing. I will check on labor to install a new pulley.

I would need to know what comes with it.

New pulley with bearing and outer clutch plate?

Thanks

Z28

I do this stuff all the time. Depending on how bad the pulley bearing is you might need more parts. Most ones I do need outer clutch and the pulley. Cars that have been driven to far might need a coil too. In cases where they really didnt pay attention it required compressor replacment where the bearing siezed and took the snout of the compressor out. Tools needed would be a ac clutch puller(Snap-on/equiv) depending on how stuck the pulley is it might slip off, need a little love tap or they do make a ac pulley puller. Its not that bad for a DIY if the compressor can stay on car.

One question is that you say the noise goes changes once the ac is turned on? Does it feel like the the clutch is dragging any bit. I've had alot of the Gm clutch have a noise( metal Scraping type noise) when the ac clutch starts to become warped and drag on the pulley which creates alot of heat!!. But when you turn the ac on it goes away. If you catch it soon enough and it the noise I think it is, you could just be able to do the ac clutch, anything else its going to need both. Let me know if you need anything else. John

Thanks for the post.

I with the engine shut off and the A/C off I looked at the front clutch plate from the bottom. I could see daylight all of the way around between it and the front face of the pulley.

I assume that the coil would pull back and close the gap to engage the compressor.

I felt very little drag when I spun the pulley but it felt somewhat rough and I head a faint grinding scraping noise.

With the engine running at idle the sound is very noticable, when I turn the A/C on, there is a pause and then a click and the noise drops by about half, but it is still there. The click is the clutch pulling in, and the noise drops because the bearing gets side loaded by the force from the clutch. That is my theory. I also ran the engine with the belt off and there was no noise, so unless I have two problems like the P/S pump and the A/C, I think the A/C is the problem.

I hope I have answered your questions.

I am concerned about getting the pulley off, due to rust. Everything has been siezed when I worked on the suspension.

Another concern I have is getting the pulley back on. The installer I have seen in drawings is kinda a bar with hooks and a center screw. The hooks go behind the ears of the compressor and the center screw pushes the pulley back on. I haven't seen those for sale around here. Pullers could be anything if you are just going to trash the compressor pulley.

The last time I had a problem with an A/C pulley it was easy to spot, little bits of bright metal flying out of the clutch.

This is a little more tricky.

Kudo's on the one lap events, I think that would be a great experience.

Z28

From your last post it sounds just like the pulley bearing is bad!!!!!. Most I do, the hardest part is getting the Clutch off. The pulley should just pull off but a little tap from a hammer is all that is needed. Unless it has gone farther. Putting it back on is nothing more than slipping it back on and reinstalling the C-clip. Again a very lite tap of a hammer is all that is needed. If you have to use the pulley puller/intaller for the pulley something is very wrong......

I would suggest to you leave the belt off until you are ready to change the part... These bearing's only have to lock up for a split second and the snout of the compressor is Junk. With the proper clutch puller it is a simple job on this car.

Thanks about the One Lap. It is a great event to experience tracks that I will never be back to unless One Lap goes there again. Namely Infinieon, and LVMS. It funnny how fast I can go with just the idea of racing for a goal. Some of the bigger tracks you need a big pair of balls to go fast in such a short time. One Partial lap is all you get to learn the track and then its off racing. Im happy with most of my results for my experience which bascially was a Short 2 day driving school and Nothing else ever.
But I do have some sad news about 05 One Lap Of America. I have been unable to secure the funds to run the event the way I would want to. So unless something major happens I will be on the bench for 05. Im going to get some more track days, work on the suspension to get the car where it needs to be and as always more power. Thanks John

What I have is part #6580037 which is the pulley with the bearing installed and no clutch plate. Let me know if you're interested.

There appear to be two different A/C pulleys for F-Body cars.

The 6580037 is a 4.2" diameter pulley.

The 6580044 is a 5" diameter pulley.

The '93 z28 uses the 6580037.

94 & 95 use the 6580044.

I checked this on GMPD and RockAuto.

The bad news is that the pulley you have may not fit your car.

I did a quick check for you and the '94 Transam shows the 6580044 on rockauto and a '94 Firebird on GMPD shows a 6580037. So anybodys guess as to what is right.

You might want to take a look at the OEM pulley and compare to the 6580037. The 6580037 looks smaller and has a step down to the 4.2" dia. The 5" looks almost straight front to back.

I don't think I had better buy the pulley, it might work fine but it looks like GM has thrown a curve ball on this part. My pulley looks like the 5".

Z28

Yes the one I have is 4.2" so I agree it may not work. I'll have to get under there and measure what's on my car. Thanks for the heads up.

How do you go about staking the new bearing into the pulley? Would a plain old punch work? Or do you really need the gm tool with the square pin and the 120 deg spaced punch slots.

Thanks

Z28

You don't need the special tool from Gm. A tap from a sharp chisel is all is needed. I usually get the pulley assembly which comes with the bearing so it is just a swap. But they do list a pulley bearing for the car 15-2802,$30.43 list or the pulley number is 15-4615 $160.00 list both are delco numbers Later John


I looked at the book before making statements.

Thanks fro the info, and checking the book.

z28

I bought a A/C clutch puller / installer off of Ebay.

I am not sure it will work. I think it does have the right thread for the compressor shaft but the large nut that screws into the clutch plate may not be right.

The compressor shaft is supposed to be 9mm. I have an adapter that is close to that.

The large remove/install nut is both coarse and fine thread. Its outside diameter is coarse .9375-23.82mm, Fine 23.92mm-.9415.

It is a Big "A" Tool P/N: 17-9870. $5.99 on ebay with $5.95 shipping. It says it is for GM A/C clutches.

If it wasn't cold, dark, wet, and muddy outside. I would crawl under the car and check it out.

So far I am afraid it is too large for the clutch hub because the Shop manual says it is 22MM. But I have seen errors in the manuals.

I bought the tool as a gamble since it was pretty cheap and had a good chance of working.

Has anyone worked with this type of tool and know the inside thread on the clutch hub?

Thanks Z28

The Big "A" Tool P/N: 17-9870. $5.99 on ebay with $5.95 shipping.

It says it is for GM A/C clutches, but I tried it today.

The threaded adapter for the compressor shaft will fit.

The romoval nut that screws into the clutch will not fit. It is too large, most likely it would work with older GM compressors without metric clutch plate threads.

So FYI, sounds like a good deal but save your money.

Z28

Finished the job on the pulley and the bearing was the source of the noise.

I bought a tool from Orileys and it had a good puller tool, but the installer would not work. I had to use the Ebay tool to install the clutch plate. It was junk, but worked one time and then most of the threads pulled out.

I got everything done allright, but staking is not very easy on these bearings the staking from the factory is in about 16 places.

The bearing is such a tight fit that the staking must be mostly redundant.

The pulley was easy to remove from the compressor nose and easy to reinstall. Spent most of my time fighting the crapy tools.

I used a large vise and some large tractor sockets to press out the old bearin and press in the new one. The bearing was $20.00.

Z28