What are the correct o rings for the R4 at the lower manifold and compressor.
 

1982 300d Turbo
3 years ago.
I changed the compressor, dryer, and expansion valve and converted to 134a. The old compressor had metal and rubber rings, but the new one called for regular looking o rings. It ran ok for a season but then blew out the o rings at the compressor manifold joint. I replaced them with more of the same type of plain orings, I have since replaced the upper manifold hose, and it has run 2 seasons with only a small loss of 134. Yesterday while parked, it blew out the orings again. I am going to replace the reciver dryer, expansion valve, and the rest of the hoses. should I use the metal seal at the manifold/compressor connection or just go back with the o rings and nylock.

The R4 compressor and its clone aftermarket imposters have used a number of different combinations of seals over the years. You will need the right seal for what you have. The metal/rubber combos come in atleast three thicknesses and are the only type seal used on real Delco/Harrison R4s for the last ten years.

One other problem we are seeing more as the cars age is the bowing of the manifold assy from overtorqing the single attaching bolt. This makes resealing impossible.

bowing of fitting
 

"One other problem we are seeing more as the cars age is the bowing of the manifold assy from overtorqing the single attaching bolt. This makes resealing impossible."

That's my problem. The upper manifold hose is new, but the rest are original. I will replace the rest of them now. The current compressor (3 years old) came with the Orings and a note they should be used instead of the ones for the stepped. (What should I use on the Orings. Since I am going to replace the hoses, what would you guess the oil charge should be. If I remember 8oz is for an empty system, so I was thinking about 6oz since I am not removing the compressor. What do you think?

By the way, I used the tips on the transmissions on your site for my old rough shifting clunker, smooth as silk now. Thanks:D