AC manifold vs compressor vs seals vs my brain pan - PeachParts Mercedes-Benz Forum

JimmyL · #1 06-08-2006, 02:36 AM

I was going to post this question on this thread:
A/c Manifold Hose - Block Configuration ?
but didn't want to hijack. (wish I knew how to "name" a link and shorten).

As you can see in below pics, my old and new compressor sealing situation is quite different (old=left, new=right). Based on descriptions in the above linked thread I'm guessing the two seals I'm showing are the correct ones. Correct??? They sure don't completely fill up the outer diameter of the openings, but we don't seal all the way to the outside, so I'm guessing that's OK.
Are those the right seals, or can you even tell?

Also, both have the same looking electrical spades sticking out for my connector. However, one compressor has an "X" on the left spade, one has an "X" on the right spade. Is the "X" for the positive lead, or does that denote something else?

I'm guessing I can mount the compressor, then before I connect the manifold can't I squirt in the oil via a turkey baster or somesuch? To avoid the well-lubed arm......

I would have still been going had it not been for the seal question.
I remember somebody having trouble getting their exp valve in and all lines connected. Wow mine went in easily. 8-10 minutes, including Nylog application.

I definitely need more larger metric wrenches. I'm waring out my 3/4 amongst others.

tangofox007 · #2 06-08-2006, 08:02 AM

Those look like the correct seal washers. As far as adding the compressor oil goes, you are going to loose most of the oil before before you can bolt the manifold up. I am going to bolt the manifild on first, then add the oil from the suction line that opens up just above the compressor (where the suction hose attaches to the hard pipe with the 1 1/4" nut.) I plan to add a little at a time and turn the compressor by hand as the oil is added.

leathermang · #3 06-08-2006, 08:16 AM

While I think turning the compressor by hand is a great thing to do... All I have seen in the MB AC manual for my car is to be sure and not run the engine above idle for at least four minutes after turning on the engine and AC. I think doing both would be the safe procedure.

Pete Burton · #4 06-08-2006, 09:16 AM

I hate to be a Pollyanna, but those seals don't look right to me. I haven't seen your hose manifold, but mine is flat and my compressor is like your old one with the 2 o-ring seals. If you tighten a flat manifold up against those seals, it looks like the load on the manifold will be taken by the torsional rigidity of the seals. I bet it will seal up, but I doubt that it will last. I could easily be wrong on this, but FWIW it doesn't look right to me.

tangofox007 · #5 06-08-2006, 09:55 AM

Quote:

Originally Posted by Pete Burton

I hate to be a Pollyanna, but those seals don't look right to me. (

What would you propose as an alternative?

Pete Burton · #6 06-08-2006, 11:15 AM

Quote:

Originally Posted by tangofox007

What would you propose as an alternative?

Seals that closely match the counterbore diameter(s), with a cross section about 10% greater than the counterbore depth. Durometer of A70. Neoprene has better compatibility with freon than buna, silicone, viton, EPDM or polyurethane.

The manifold needs to make metal to metal contact with the compressor casting all the way around both counterbores, so as to take most of the compressive load and vibration. Otherwise, the seals will, but not for long.

p.s. Maybe that's what they use in those "stepped port" compressors. Maybe the metal rings around the seals crush somewhat and the manifold is spaced away somewhat. Just looks like a less proper way to do it than the simple, trapped o-ring IMHO.

JimmyL · #7 06-08-2006, 11:23 AM

Quote:

Originally Posted by Pete Burton

I hate to be a Pollyanna, but those seals don't look right to me. I haven't seen your hose manifold, but mine is flat and my compressor is like your old one with the 2 o-ring seals. If you tighten a flat manifold up against those seals, it looks like the load on the manifold will be taken by the torsional rigidity of the seals. I bet it will seal up, but I doubt that it will last. I could easily be wrong on this, but FWIW it doesn't look right to me.

My manifold looks like the one in this pic. There certainly isn't alot of "seal material" around the yellow washer. The green one seems to have alittle more. I'm not sure what else there could be though.
Anyone else ever get a compressor like this, and remember their seal setup?

**edit**
I got this compressor from Fastlane. Is it possible this compressor is not compatable with our manifold setup?

James L · #8 06-08-2006, 12:08 PM

you want about a 1-2mm gap between the manifold block and the compressor. on my 1984 i used the green one on the discharge and a black one on the suction, there was not a yellow (ackits new R4), just a red, green and black. i did the red/black and it was crooked and leaked (you could hear it hissing with the vacuum pump running). reinstalled green w/ black and it was not crooked but straight across and all around. there is a 1-2mm gap and no metal to metal contact, does not leak. used nylog.

the o rings are with the remaufactured compressors and the GM type seals are with the new compressors.