Rob Edwards

Well, this is how it worked out:




I may be able to re-seal a compressor, but I can't freakin' properly torque an A/C compressor bracket bolt. The rear bolt is completely gone (musta fell out....), and I think that I snapped the front bracket boss when turning on the system a few weeks back. Oops. Turns out 1 mounting bolt and the tensioner bracket aren't enough to hold a compressor in place when the clutch kicks in. Hoocoodanode?

Rob Edwards

So I re-built this compressor about 2 months ago, and it worked for a couple of weeks and then quit, as the vent temps slowly climbed back up to ambient. I had made a quick look underneath about a month ago and saw what looked like oily gunk coming out from under the clutch, so I figured that I'd gotten the shaft seal wrong and that the charge had leaked out. I then ordered up a rebuilt compressor.

Well, I put some gauges on the system and found the R12 charge was intact. So I had the system evacuated, then came home and put it up on stands to A) install a PKsn'r, and B) R&R the compressor. This is when I found the cracked mount (see above).....

As a pathologist, I couldn't resist a little post mortem on the compressor. I didn't open the sealed compressor (other than the manifold plate, in order to drain the oil). But y'know that picture above where I measured the air gap in the clutch? I don't think I know how to measure air gaps:



So either I don't know how to use a feeler gauge, or I over-torqued the face plate, or ???

Perhaps this is best left to professionals.....

dr bob

Rob-

There's not a lot of magic to the air gap thing. If you were able to barely stuff the feeler gauge into the space between, you got it right. More to the issue-- does the conpressor crank still turn? Damage to the friction faces like that is usually due to a siezed crank, while the belt motors on.

In my collection of stare things, I have a brand new compressor that looks a lot like yours (and nothing like mine...) that you are welcome to have. IIRC it was less than $50 at a swap meet some 20 years ago, so with depreciation, wear and tear in storage, etc, it's yours if it will work. Has the same bolt-up that Griff's has. I need to go take a picture I guess.

Rob Edwards

Bob-

Thanks for the offer, I will take you up on that if it'll fit. Is there a Denso sticker on the rear? I'll have to measure the mounting bosses.

The compressor itself turns fine, nice and smooth, I turned it easily by hand to drain all the oil out of it. And it was holding the freon charge just fine, I just somehow managed to trash the clutch. (Did I just eat my core deposit, Jim???? )

dr bob

Rob--

Sticker says Nippondenso 10P15C 047200-2322

R12, Densoil 6

Mounting is 130MM x 80MM centers

55MM from front mounting center to pulley center.


Port plates look like standard ND so yours should fit fine if it will mount up.


Comes with just a little bit of free OC real estate that can be cleaned off easily.


The part number after the ND looks like a Toyota number, and a quick google finds that it was used on Supras as well as several other makes like MBZ and Land Rover. I picked it up to replace the GM compressor that came in my Saab Turbo way back when, but it turned out to be too deep to fit behind the turbine housing with a heatshield. So the car went back to cranky R4, spare went into the 'someday' bin. Yours if you can use it.

michaelathome

I just yanked my compressor last night and I am glad that it was not working, I was missing the upper rear mounting bolt for the compressor (M10x45).

Also looking at this picture, what is the bracket that runs from the front to the rear on the bottom of the compressor, mine did not have that either and I was unable to find it in PET.



Michael

Rob Edwards

Michael-

There is a 90 degree bend at the front of that bracket to which the A/C belt tensioning adjuster bolt connects. Looking at PET, I think (THINK!) that bracket is item #16 (see below), though the diagram only shows the forward part of the bracket, and it also shows the tensioner assembly (#12, which doesn't exist in the form shown in the PET image....) attaching to the REAR of the compressor. I think MC Escher broke into the drafting studio that day, or maybe it was Oktoberfest.....

EDIT: You have an '88, so you should have a Denso 6E171 compressor. I have no idea what the compressor bracketry should be for that set up, but I'm guessing it's different from what I've pictured. My pics are specific for 90-91, or a '92 ROW GTS with R12.

Bill Ball

Rob:

I've had coils get damaged like that. Last one aparrently was due to me forgetting the outer C-clip. Well, that is, there was no C-clip present when I took it apart. I don't know of a place that sells the coils separately. Denso sells a very nicely rebuilt (looked like new) clutch for $122 through Amazon. That's a much better deal than $200 for a used clutch from 928 Intl. [LATE EDIT: The new clutch took a dump too. Eventually I came to the conclusion that the compressor was partially seized and was overheating any clutch put on it. Replaced the compressor and the clutch stopped burning out.]

Rob Edwards

Hopefully this'll avoid anyone else making a $50 mistake- The 10PA20C compressor mounts to a curved bracket (#9) that then mounts to the bracket bolted to the block. The curved bracket is aluminum and is threaded to accept two compressor mounting bolts, #7 and #8. The catch is that they're fine pitch . Don't (as I did) just go jamming a standard M10 x 1.5 bolt in there, as you'll booger the threads. I could have helicoiled the bracket, but $28 for a helicoil kit vs $50 for a good used bracket from 928Intl seemed like a reasonable alternative. Tom says this is a common mistake (maybe he just said it to make me feel better....)

dprantl

I had the same issue as you a few months back. That exact rear bolt and the insert that the bolt fits into was very loose because for some reason the hole in the upper bracket somehow became enlarged. This caused undue stress on the front bolt and eventually cracked the front part of the bracket off, just like your picture. It seems this not such a rare problem.

Sometimes it's REALLY nice to have a spare 928 engine on a stand. I have one in the garage from an '89 that had TBF and there are so many parts that I've already scavenged from it. I just exchanged the bracket in the car with the the one from the engine on the stand which was in good condition.

Everyone should check the two top bracket bolts of their A/C compressor and also the bolt that holds the belt adjustment bracket in place.

Dan
'91 928GT S/C 475hp/460lb.ft

Leon Speed

In my search for more rebuilding instructions for my 6E171, I came accross these videos. This is for 10PA compressors, but it should be the same for mine. These vids contain some handy tips. One is that he pre-expands the new seal by running it backwards over the shaft seal protector.

danglerb

One of the reasons I bought a rebuilt compressor instead of trying the rebuild myself is that it seemed like parts were more expensive than a quality rebuild to people outside the trade. The replacement clutch was almost as much as my complete rebuilt compressor which included a new clutch.

Leon Speed

Rebuilding in my case is resealing but if I would need a new clutch and it is near a rebuilt compressor, I'd buy a rebuilt one.

IrishLegend

tag

namasgt

Has anyone else attempted this with success?
Seems straight forward from the 2 videos. Can't see the pictures Rob posted.