CUTLASS Rebuild an R4 compressor? Piece of cake.

[69hurstolds]

A tad long, but there's a lot of good info you may can use if you decide you want to tackle a reseal job on your R4. I had to repair mine, but if yours leaks, doing a reseal job is almost as intensive, but not as invasive as what I needed to do.

Yesterday, I completed, sort of, a 1131198 A/C compressor conversion from a 1131622 compressor. My plans are to use it on my 85 442 temporarily as an experiment of sorts to see if R152 actually works. I didn't take pictures because 1) there's a lot of videos on how to reseal a compressor both shell and shaft seals, since that's a couple of the major leak points of these things. GM decided in their infinite wisdom to use a single lip shaft seal on it, and 2) I was too lazy. This isn't a hard job, but you will need a couple of specialized tools, and it really helps to have a GM CSM handy.

I had the original 622 that came off my 87 442 that puked and choked soon after I bought it. It turns out it blew a piston off its rod and mayhem ensued. Locked it down and instantly fried the clutch to boot.

For those who haven't messed with the R4 compressors much, there are TWO types used on Cutlass. I cannot attest to any other G-body as I don't own or work on them, so I only know the 198 and 622s. Up through mid- model year 1986 they used the 198 on Cutlass. Then the 622. The main difference is the front bearing housing and the internal cylinder shaft, which cannot easily be removed by the regular Joe Mechanic. It's basically part of the assembly. The shaft is about 5/8" shorter on the 622 than on the 198. Why? I don't know. Uses the same seals, but it's called the "short shaft" and the 198 obviously, is known as the "long shaft". The drive clutch is a different part number, yet everything else left is the same. Interestingly the seal area on the 622 and 198 shafts are in the same place. Although, the 198 does have a couple of flat spots on it near the rotating assembly where the 622 does not.

The rotating assembly cannot be easily dismantled. The pistons are press fit onto pins on their connecting rods and apparently once one of them let loose, it's done. And no repair parts were sold separate to fix it anyway.

Getting the rotating assembly off was a bit daunting. With the belt pulley, it's that big ol' monster in front. It's best that the magnet, and pulley, and rotating assembly with rotor bearing comes off TOGETHER. They can be disassembled after removal. You can remove the 6 little perimeter bolts on the pulley beforehand, but then you will need to use a puller to get the magnet loose anyway. Don't damage the ceramic on the magnet, though. It wouldn't take much to pull the magnet part, though.

With the serpentine pulley, it's much easier to remove. In fact, I even have a puller for that style. But the belt pulley needs a small, specialized 3 leg inside puller to work. Problem is, it's a unique little unit and many of the small pullers I was able to get my hands on won't work. All is not lost. I figured since I had new GM pulley, magnet, and rotor assemblies, I could try it with a 6" puller on the back of the pulley. If something got hosed, then I'd just use new parts. Going slow, I was able to bring the entire assembly off the nose with very little effort on the puller's part. My fear was bending the pulley, but that didn't happen.

I put a new bearing in the front head (bolt-on nose) assembly. A little roller bearing. A note about this. There's an oil hole on it that SUPPOSEDLY it's supposed to be in the 12 o'clock position when installed to allow oil to drain into the front shaft bearing. It's marked with a little cast-in "X" on the top to mark where it is. X goes up. However, some Mercedes cars using the same compressor has the X facing down when mounted. Not sure if there's anything to this, but hey, It came out in the 12 o'clock position, so it went back the same way.

There is one definite thing you should know about R4 compressors that sit around on your shelf. R4 pancake compressors take a bit of effort to turn as it is. But after a while, they get really stuck. Not impossible to turn, but there's not much place to grab onto the drive clutch to turn it. You do not want to use the 9/16" nut on the end of the shaft, you will likely twist it off.

And here's why I believe it gets tougher over time. The piston seals appear to be some sort of rubber and or rubber/fiber compound that resemble an oil-less air compressor piston seal ring. But interestingly, when the piston is brought to the bottom of the bore, a portion of the piston seal is brought down BELOW the bore, being exposed. Two pistons are up, and two are down at any given time due to the rotation of the cylinders. If the assembly is left on the shelf with a piston all the way down, the exposed portion of the seal expands slightly over time, making turning of the shaft nearly impossible. This goes for the replacement rotating assemblies as well, if you have any. I used a drive clutch and a webbed (not rubber) strap wrench wrapped around the drive clutch (not much to grab onto, though) and put the shaft key in and was able to turn it around and "break it loose" so to speak. It's a **** if you don't have a good method to hold the cylinder. I have a shell remover/installer tool, and it comes with a "leg" on it to use in a vise to hold the compressor guts. Ultra-handy, but not absolutely needed.

Another important tip in doing this job is that besides the shell o-rings leaking, the shaft seal leaks too because of it being a single lip seal. Which works fine when running. Delco used to sell a double lip seal, which I have a few on hand, so that's what I used. It's infinitely better at stopping leaks, especially if the shaft is stopped. Delco replacement shell o-rings are buna-N, which are great with mineral oil and R-12, but most kits you can buy aftermarket have better materials that are more compatible with R134/R152. So I used those. With those two items addressed, I think it will stand a better chance of not leaking. We shall see.

SO....

Since it was going on the 85, I figured I might as well look the part. I didn't want to buy one of those light duty R4 compressors, and everything rebuilt by the mass rebuilders I don't really trust anyway. I re-used the magnet and honker sized pulley with the 6 bolts. I used a new rotor and drive clutch because the old ones were toasted anyway. Besides, I was converting over to a long shaft anyway, so the replacement part was for the long shaft.

If you can, use NEW drive clutch and rotor if possible if you have to change them. "Rebuilt" clutches means they resurface the clutches and may trim them off too much which reportedly causes cracking over time. Don't know for sure, but there you go. You do you.

There is a special key the factory and GM replacements use for the drive clutch mounting. It's SLIGHTLY bent in the middle, with the bend peak facing away from the shaft during installation. I'm basing this on how I found it when removing.

Additionally, one last tip. Using the drive clutch installation tool, get some feeler gages to set the "gap" between the rotor and drive clutch faces. The spec is 0.020"- 0.040". I set mine to 0.030" nominal clearance measured at 4 different places around the clutch. SNEAK UP on the setting. The clutch installer tool has coarse threads, and moves the clutch in quite a bit rather quickly. So when you get close, go slow. If you get it too close, you'll need to use the puller to move it back out. PITA.

 

[rfpowerdude]

Well, damn. What a helluva write up!

 

[ELCAM]

Good info, here is a little more.

The A6 and R4 use the same bent key.

The A6, R4, V5, HD6, HR6, HR6HE, DA6 and HT6 all use the same front seal so the double lip seal is easy to come by in the aftermarket.

Attached 1984 Cutlass CSM R4 rebuild section as a photo PDF.

 

[69hurstolds]

Good info, here is a little more.

The A6 and R4 use the same bent key.

The A6, R4, V5, HD6, HR6, HR6HE, DA6 and HT6 all use the same front seal so the double lip seal is easy to come by in the aftermarket.

Attached 1984 Cutlass CSM R4 rebuild section as a photo PDF.

Great info! That same procedure is in the 85 CSM as well, with only minor little changes. In 1984, R4 got rid of the R4 ceramic seals and moved exclusively to the single lip seal. GM p/n 2724319 since 1984 is the callout for the SINGLE lip seal in the parts information. This part has been superseded about 8,000 times since 1984, so you would need to watch out for that. Oil seepage from a lip seal is ok. It may be miniscule, but it's fine. It's what it does. But you should NEVER see refrigerant leaks or massive oil leaks.

I knew the A6 had the same seals as the R4, but never paid much attention that nearly all of them share the same seal. I don't buy much aftermarket stuff unless I absolutely have to. The only aftermarket seals I bought were O-ring kit for the shell rings due to being used in a conversion to replace the factory buna-N type seals.

If you are changing the front seal and get a choice, go for the latest supersession part number of ACDelco seal 15-30948 or GM p/n 89019204. This is the part number I used and it is, indeed, a double lip seal. Unfortunately, now it's been discontinued. It never mentions this in any GM parts literature that it is a double lip seal, but you can definitely see the two opposing lips on the seal ring itself. So watch out for those parts with superseded numbers written over the 2724319. You don't know exactly what you'll get. Did find some interesting information digging around to see if any previous part numbers were, in fact, double lip seals. From 2003, "GM Tech has indicated that the new GM double lip seal ACD# 15-30948, GM# 2724954 for HR6s and V5s will backfit into the A6"

The previous interchangeable seal number to 89019204 is 2724954, thus using any of these two numbers should net you a double lip seal if you want to use GM parts. And if you want to use aftermarket parts, you can use pretty much any kit as most of them are nitrile, which is 134a and R-12 compatible.

A list of aftermarket seals that are double lip seal equivalents is here. So if you get these seals, you can use them in your R4. This is JUST the seal itself, not any kit with extra parts.

• UAC # SS7481
• Sunair # MC556DN
• Sunair # MC556D
• General Seal # GSLD356N
• Santech # S131002
• Omega # S131002

No need to say it, but just in case, always use a seal protector when installing the shaft seal. ALWAYS. You'll never be able to avoid a damaged seal if you don't. This is one specialty tool you cannot do any R4 seal job without.

Some compressors use a high pressure cutoff switch mounted in the back, separate from the relief valve. 198 and 622 compressors have no such animal. In fact, the OEM (and some early replacement guts) do not have a hole drilled in that location. The high pressure switch cuts off power to the solenoid effectively shutting off the compressor to keep from damaging it during, well, high pressure conditions, such as WOT. Cutlass VIN 9 through 85 used the WOT A/C compressor cut out switch on the gas pedal so as soon as you mashed the throttle to the floor, the compressor kicked off. It is controlled by the ECM in VIN Y and VIN 9 moved it to the ECM in 86-87. So no real need for the redundant switch. But later, with parts consolidation, the rotating assemblies all came from GM over the counter parts with a high pressure hole, but plugged. So you could add a switch as you needed it.

Another thing to remember with R4 pancakes is that they use SAE threads on the older stuff. Early 80s they keep the SAE threads on the drive clutch for removal, but the rotor assembly (tapped mounting holes) and rotor shaft use metric threads. So be careful out there.

 

[69hurstolds]

Anytime you ever have to work on one of these compressors, if at all possible, rebuild a stock factory unit if you can. Like I said, a handful of special tools is all you really need, you can do it. GM parts are still semi-available on the secondary market, but aftermarket seals are plentiful. Probably the biggest PITA is getting the pulley bolts off having to bend up the locking effect of hammered down edges along the front. There's a light thread locker on the bolts as well, which I find as overkill. The flanged edge is bent down over the front so those bolts aren't going anywhere.

The two compressors virtually used for the majority for 80s Cutlass is the 1131198 and 1131622.

Here's a few pics of some new ones I have.

The 198 and 622 are very similar as stated previously. Code No. (build date) of this one is September 11, 1986, 2nd shift. The 622 replaced the 198 midway through the 1986 model year. They are TOTALLY interchangeable with each other.

The 198...build date February 16, 1985 (aka "Code No.). First shift. It can't be 1995 because by 1990 they had a different part number service replacement by then.

Note the end of the shaft is almost flush with the drive clutch. That's why they call it the "long shaft".

Note, there's just a innie dimple where the high pressure cutout switch would normally be on a Chevy. Oh, lookee here. Someone put a piece of tape over the relieve valve port. I guess to keep paint out of the hole?

Note the gap on this puppy's clutch. TIGHT. Which is ok. Pulley spins freely. Before I use this one, it's getting new shell O-rings and a new double lip shaft seal. So it will have to come apart anyway.

and here's that "X" I was talking about for the oil hole to the front shaft bearing alignment. Never mind the box "dust". It's that molded paper fiber filler part that wraps around the compressor while in the box.

 

[69hurstolds]

OK OK... I'm sure there's a few of you that want to see what I did after I converted my 622 to a 198. It's basically new. New guts, everything but the re-used shell. Reused the relief valve though. Reused the front head and bolts, but put a new bearing it it, new O-rings and seals, and a new clutch hub and drive clutch. Reused the pulley, the pulley bolts, and the magnet. Works and tested fine. I got new ones, but didn't need them.

I did a check on the drive clutch and wondered why the part number was different on it, but yet not different on other parts of the clutch. I think I might have figured it out. I've yet to measure it, but it appears to be the same with, I believe, the exception of METRIC threads on the inside area of the clutch. I'm going to dig more into this when I have time, but I believe that's the only real difference. I'll do some measurements to make sure it's not something to do with that. As stated before, the shaft is about 5/8" shorter on the 622 than on the 198, and that's about all I know for sure right now.

Here it is. I'm using it on my R152a experiment. I just threw on one of my prototype decals. Thought about making one that said R-152, but nah, nobody reads these things anyway.

And of course, gotta have the "X" on top.

 

[olds307 and 403]

Great job, as usual. I did a new clutch on a 94 model, what a PIA to remove, I had to combine two pullers. Unless you are using these on special G bodies, which you will, I would avoid these POS. They always eventually leaked, rattled then seized for me. Your rebuild is probably better than any reman. I really want another 88 to 95 GMC/Chev 4x4 to Olds power but the 4L60E and these garbage compressors are deterents. That 94 leaked from the extra pressure switch. A new O ring did nothing to stop the leak. Carry on🙃.

 

[69hurstolds]

Thanks. I took that sucker down to parade rest. Here you can see a GM/Delco cylinder kit which is what I used. The 4 pistons have dual-duty disc inlet/outlet valves for sucking and blowing. Those grooves on the front and back are critical for sealing as the stock o-rings tend to leak. These cylinder assemblies ARE NOT SERVICEABLE. I'm sure someone probably could if they had all the right specialty equipment, but there's no way I was going to even attempt to tear down my old one. Proof will be in the pudding, though. If it blows chunks I can only point to the dough-dik mechanic that repaired it- in the mirror.

I did a bit more research on the PAG, POE oils for the 152 changeover, and I think I'm going to settle on the PVE oil. It's a POE substitute, but the best thing is when you evacuate it, it gives up the moisture, unlike POE.