Nicole

Well... I had to try out putting the car on jack stands today, and it was pretty straight forward, thanks to all your suggestions!

Next tihing was to pull the belly pan off and clean it. Gosh, the rear aluminum part was pretty manged up and has thick layers of grease on it. As I was cleaning it, I noticed that the support brackets seemed to pull off the pan, wiggled one a little, and off it came. Maybe that's the occasional vibration noise I heard from under the car, at about 2900rpm??? OK, I'm in the market for a used rear belly pan, not too badly banged up, please!

Next, I decided to inspect my mega-noisy AC compressor. In fact, during a short drive on Friday it had become so noisy that I thought I had a diesel engine in my car. At that point I had decided not to drive the car until this issue has been taken care of. I sure would not want to risk a seized compressor. I have learned that once that happens, you lose about $600 in core charge... Ouch!

I briefly started the engine and used the hose of my shop vac to see, if I can narrow down the source of the noise further than just "somewhere on the compressor". Sure enough, holding the front of the hose at the center of the pulley made the noise most prominent - clicking and scratching and clicking and scratching - it sounded baaaaaaaaaaaaaaaaaaaaad!!! Thanks, Bill, for showing me the vacuum hose noise locator trick - it works perfectly!!!

So, what to do now? As it was scratching and clicking too badly to drive it anywhere, I had three choices:
1. Cut the belt
2. Have the car towed across the Bay and get the experts to fix or replace the compressor
3. Find a cure in my garage

#1 looked scary, because there are three other belts in front of it. They would all have to be taken off in order to install a new belt later - something that looked like a major pain I would not want to go through (if I could even do it).

#2 might not make my insurance very happy, as they have towed the car before, and it would cost me alot of money at a time when my budget is tight. I decided to keep this option as the last resort...

So #3 it was. I had already studied the shop manual when the noise started, and seeing the compressor in the car did not look all that intimidating. The scary part, however, were all the hoses and other stuff around it. Now much room to work, and I don't exactly have a well equiped tool box...

OK, I decide that there is not much to lose, and I'll play daredevil. Took the front nut off the compressor, and the front coupling just slid off. Now the pulley...

Maybe it would be helpful to reduce belt tension for this part - if only those darn adjustment nuts would move. But they would not turn even one bit! I call SharkSkin and ask for advice, and he suggests getting liquid wrench. Kragen doesn't have it, so I get one of those wonder-sprays, "as seen on TV". Two hours later, I still can't move the damn nut!

In the meantime I battle with the C-clip that holds the pully on. I speak with Ron H, who recommends getting some circlip pliers - I had never known these even exist. Talk about a mechanical beginner! I know how many things work, but have no clue how to take them apart properly or put them back together! My tool set can be described as "Do it herself", rather than "professional". Now you know why I rarely attempt mechanical work on my cars...

I try one more time with a small screwdriver, and the C-clip pops off. Uh, that's cool, so let's see, if the pulley comes off a easily as the coupling. Well, it moves... until it hits an AC line. No chance without pivoting the compressor out of the way, which would also reduce belt tension. So I'm off to Orchard to get a longer 13mm wrench that gives me more leverage to tackle those tensionier nuts.

Back from Orchards with my new wrench, the adjustment nuts suddenly move easily. But I have the same problem with the nut that holds the AC compressor at its pivoting point. It does not move! At least, turning the adjustment nuts in the right direction tilts the compressor enough to get the pulley off (with the belt on).

And I cannot believe what I hear when I spin the thing. Holy guacamole - this bearing is probably as shot as it can get!!! And it sounds very much like the clicking noise I had heard before. Somebody must have put sand in there...

The question that lingers is: Is the bearing the only source of noise on the compressor? If so, why did the scratchy part of the noise not go away when the clutch was engaged and the pulley turned with the rest of the stuff? Shouldn't that bearing rest when the clutch is engaged?

Well, I think I'll have to take a chance. I need to get the bearing replaced in the pulley, put things back together, and see what it sounds like. I am now pretty confident that I can put things back together, once I get the bearing replaced in the pulley.

I hope I can get the bearing locally or quickly by mail. The bearing type is "NACHI 3066055205 0" - if I read it correctly. NACHI website does not list this number onder AC bearings, but it can't be that exotic, can it? BTW: This is a different bearing number than what's posted on Greg Nichol's website under "Compressor Bearing Replacement" - this article is about an '83 Euro, which seems to have a different compressor than my early '91 S4.

I want to thak Bill, Ron and Dave (Sharkskin) for their encouragement to explore this issue! I just wonder, why it is so much harder to get things done when Bill is not here. Must be because watching is easier than doing...

Below are pictures of the pulley from the front and back side. Hope you were able to learn something from this writeup! I will add to it when the bearing has been replaced.

Ron_H

Let's here it for Nicole who tackled this job all by herself. Anybody know where she can locate a replacement bearing?

worf928

Three Cheers for Nicole!


Nicole, your story of finding something, needing a tool, going to the store, finding something else, needing a tool, going to the store...

... sounds distantly familiar.

justin

Nicole, Any good parts store should have that bearing in stock, just take the old one with you when you go.

SharkSkin

Awesome Nicole! Simply awesome! I knew you could do it!

A couple of quick points here:

• Maybe you can get the belly pan welded... might last a year, meaning you could take your time finding a replacement. Might last longer... depends on how the job is done.
• Now that you've taken one belt off, you can do any of the others! Well, best not jump into the TB just yet...
• You forgot Option #4, or 1.5, or whatever: Cut the belt and drive across the bay. Again, big kudos for not chickening out.
• Keep an eye out for the Liquid Wrench. I think OSH carries it. NAPA, etc are places to look too. It might have loosened things BEFORE you went for the longer wrench...
• Be careful buying circlip pliers. Most are crap.
• $600 for the CORE? My whole kit, NEW compressor, hoses, dryer and o-rings was only a little more than that... jeez... I think of myself as a purist, but only to a point...
• Shark projects without trips to the store are rare in my experience... Even when I plan ahead and get the hardware I think I'll need, inevitably there's one more thing... or two...

I've already said that those symptoms make me suspicious... Look for any evidence of rubbing between the parts you have removed from the compressor and each other. Inspect the compressor nose for evidence of scraping as well. Turn the compressor one revolution. No issues with any of the above? The only way to be 100% sure is to start the car with the AC disconnected(you can tie-wrap the AC belt to your dipstick, etc so it's not an issue; I drove like that for a week). If the scraping is gone, you've at least confirmed that the sound is in the AC. If you still hear scraping, find it... it's probably the smog pump. That's a much cheaper pump; it can be had for a mere $50 rebuilt...

I made my best effort to enhance the pics you posted, and I don't see any evidence of rubbing. The friction material on the front does appear to have a small crack at the 5:00 position, unless that's the way it was manufactured.

My favorite place to get bearings over the last 25 or so years has been King Bearing in Mountain View, though there is one closer to you. They don't exactly have kiss-your-*** customer service, but they know their stuff and can get you what you need. Very likely they will have it in stock.

Again, three big cheers for Nicole! You go, girl!

Nicole

Thanks, everybody, for your encouragement! Today I remember why I did not chose to become a mechanic or chimney sweeper...

I've been in the garage in the meantime and tried to turn over the compressor. To do this I temporarily stuck the coupler onto the front of the compressor and was able to turn it with my hands. It turned smoothly as far as i could tell, and there were no scratchy noises. So, there is hope that the clutch bearing is the only serious problem.

Dave: You have really sharp eyes - I had not noticed that little crack in the rubbing surface of the pulley until I checked. It's hardly visible, and I doubt it affects the function of the clutch. Should be OK...

In regards to the aluminum underbelly pan: I will try to find a nice one, but if I don't, I might just drill out the old welds and use a rivet gun to put the thing back together. That'll work for the time being without having to take the thing elsewhere and pay for welding, when I really want a complete, straighter pan.

Ispeed

My belly pan was nearly falling off like you described, and I straightened it all out and riveted the hell out of it to connect the flimsy arms back to the pan. Was able to clean the gunk as well.

I still think a quick-detach belly pan set-up would be the best. If I go to synthetic oil, less frequent oil changes, maybe a non issue.

Nicole: congratulations on diving in under the shark! Awesome.

Nicole

Carl: You don't have to change the oil more than once a year or every 12-15k miles anyway. The 928 has such a large oil reservoir, and the modern olis last forever (even the fossile based ones), that some European car makers now recommend 30k kms (20k miles) change intervals!

My friend at Porsche told me that as little as I drive, I could even go 18 months without worrying, and Doug Hillary's oil research (as posted on this board) confirms just that.

Nevertheless, a quick access belly pan would save labor cost or time whenever something needs to be fixed - that can add up quite a bit over time!

In fact, there is one funny detail about the current belly pan arrangement, that doesn't seem to make sense to me. If you look at how the pieces overlap, thefront of each piece alwasy points downwards. I would think it would be easier and safer to overlap the pieces the other way - no?

Ispeed

A friend of mine is a welder, and does a lot of work with sheets of aluminum of different thicknesses. I wonder if a one piece belly pan would be a good idea, maybe with a smaller removable panel for oil changes.
I bet a fabbed up rear pan welded to a Devek front pan and modified with removable oil change panel would be better. Those louvers would be hard to duplicate.

p.s. I'm off now to bring the Weissach home. Was waiting for a fuel pump relay and a good co-pilot for the trip. Cigars all around!

Garth S

Bravo Nicole!!!
Now for step #2: Once you find the bearing of your dreams, it is likely the old one has to be pressed out, and the new one pressed in (see yesterday's post under "timing belt roller ...") - likely you can talk the shop into doing this.
Next, It is really easy to bend the compressor adjuster bracket unless the pivot bolts in the top are loose: The one in behind the compressor (17 or 19mm) cannot be accessed with a wrench - off to the store for 1/2" socket set ... this way, you'll have a 5 ft high Snap-On tool caddy chock full of new tools by next weekend!
Best of luck!
BTW, if you have a drill, the quick fix for the undertray bracket is to poke a couple of 5mm holes through the pieces and bolt it together - will last for life! and a jug of 'simple green' and a hose will clear up the mess before reinstalling.

Lagavulin

Nicole, I learned you've got ***** to tackle the job by yourself; good job!

Next thing we'll know you'll be posting about bolting a supercharger onto your car...

Just kidding!

Thanks for the write up.

Styln928

Outstanding job Nicole, I'm impressed. There are some easy things to do on our cars and I get lazy and send it out. But seeing you do this makes me want to get crackin'.

borland

Nicole,

On the belly pan. I modified mine so I could remove it without unbolting the large brackets that are spot welded to the tray. I was afraid that after a few more removals, the bolt hole threads in the car's body strip and I'd have to use a larger bolt.

What I did was to drill thru the spot welds in order to liberate the brackets from the tray. I reinstalled the pan to the car using 4 speed nuts which fit over the drilled holes. So you only need 4 speed nuts, 4 belly pan screws and washers to complete this mod.

On the compressor bearing. That is a special bearing that you are not likely to find at automotive parts houses. Your compressor is a Nippon Denso 10PA20C. The part is available from bearing suppliers or a/c parts suppliers. Here's a source, $28.26 plus shipping.

http://www.acsource.com/index.asp?Pa...S&Category=317

Hope you have a bearing press.

On the noise, you due to the limited clearance between the spindle and the shaft, dirt can cause noises. Dirt source can be the clutch surfaces.

When installing the nut, it may be difficult to counter hold the compressor shaft. I suggest that you use blue locktight on the bolt threads.

Good luck with the repair.

mpesik

Nicole. Now if I can only get my wife to work on hers.

WallyP

Nicole,

Way to go!

The pulley bearing spins anytime that the engine is turning, regardless of whether the A/C compressor is turning or not.