I had a leak in my 1979 240D AC system, but the system worked great when charged. It had been converted to 134a long ago - the ports were changed and there was a sticker that had completely faded away where the conversion sticker should go.

So I thought I would replace all the seals and the manifold, drop in a new dryer and recharge.
I bought a new manifold seal kit (the kind with the red green and brass seals)
I changed all the seals and the system still leaked, so I opened up the manifold. The manifold looked the same, but the compressor was different.

It is a Delco R4, labeled for R-12. Both ports have a tube with a recess around them where two identical o-rings sat. The seals don't seem to fit since it is not a flat cup sort of shape, but rather a donut in there.

Can I go to the local McParts place with the O-rings and source them there?

I have never seen this style port on a w123.

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1980 orient red 240D 4-speed
1979 maple yellow 240D 4-speed

Yes, there were more than one seal configuration used during the run of the R4 compressor. If there is an auto a/c shop in your area, he should be able to fix you up.

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Larry

'88 300E 5 speed manual, 333K miles
'99 SLK 230 AMG, manual transmission
Cessna 140

"Change oil hot and change oil often"

“I'd like to know why well-educated idiots keep apologizing for lazy and complaining people who think the world owes them a living.” - John Wayne

The "O-ring port" type R4 compressors are the original MB style and seal better than the "stepped port" type.
You're lucky, they are rare nowadays.

No doubt - manifold sits on there perfectly - no gap like the other type.

Went to Carlisle Auto Air and got a pack of 10 o-rings for $3 - sure beats $20 a one-pack of the other seals!

So how do you find o-ring style R4 compressors? I want another for the other 240D!

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1980 orient red 240D 4-speed
1979 maple yellow 240D 4-speed

One of the three Compressorworks R4 compressors I bought was of the o-ring type. Last one was stepped. It's hit and miss...

Three different cars, all are still performing well.