A/C compressor failure - anybody seen this?

[Zero10]

I finally found the source of my A/C leak in my 951. It seems that the manifold ontop of the compressor (the big assembly bolted on with 4 allen head bolts) is leaking all around the edge. So, I took the compressor from my 86 (which AFAIK wasn't leaking) and installed it. This compressor leaked from exactly the same place.

I have never heard of a compressor failing in this way before, let alone 2. Has anybody had this happen to them?
I've heard of lots of front seal failures, clutch failures, etc.

Given that it is just a manifold/plate, can I just use loctite 518/574 to re-seal the flange and use the compressor?....

I have 2, so if nobody knows I'll be the ginuea pig and give it a shot

[bazar01]

I have never replaced a 944 a/c compressor yet but it should be similar to other compressors.
Isn't there supposed to be an o-ring on each port to the compressor? Have you checked those? Maybe the o-rings are already hard and compressed causing the leakage.

[Porsche-O-Phile]

Try sealing it. Can't hurt I s'pose. . .

[Zero10]

There are O-rings where the lines connect to the manifold, I have changed those several times since I originally suspected that they were the points of failure. It wasn't until I had the motor out of the car that I could get a clear view of the problem however.

While the motor was out, I built a big pile of wheel ramps/wooden blocks to set the A/C compressor on, and gave the system a partial charge of Red Tek. I allowed it a minute or two to equalize throughout the sytem and fired up my leak detector. The leak with both compressors is large enough to smell the refrigerant and to be audible, so of course my leak detector was going absolutely crazy, but if I kept a fan on the area to help dissipate the fumes I found that all around the edge of the manifold plate my detector was giving me it's highest reading.
I checked the rest of the system twice for other leaks and found none, including placing the sniffing end of the detector around the high and low pressre ports, and the O-rings discussed above. When the engine is in, you cannot really access this part of the compressor, and it appeared that perhaps the low pressure service port on the compressor was leaking or else one of the O-rings, so I changed the valve core and O-rings several times (to great frustration) in an attempt to fix the leak.

Now, as to whether there are O-rings under this manifold plate where it mates to the A/C compressor, I cannot answer. However if there are then this will be one super-easy fix
Otherwise I will remove the plate, apply flange sealant around all of the mating surfaces and re-install.

Unfortunately, I have left my leak detector, loctite 518 and spare A/C compressor in Calgary and I am now living in Vernon (about 7 hours away). I will be back in Calgary on the 16th and will pick up my spare compressor and remaining parts/tools then.
If I have not received an answer before this time, then I will tear apart one of my compressors in search of answers. Nothing to lose I suppose If possible I will borrow a digital camera to document my surgery.