83 300SD; long A/c overhaul story, condensed. Compressor swap - new Delco R-4. I bought and installed a #4354, using the same sealing washer configuration that worked perfectly before (and even tried some other combos), but it immediately leaked oil (no freon charge yet). Checked old compressor, discovered it is a #4857. Compared the two, but I cannot detect any external differences from #4354. Have not precision measured, but diameter and depth of recesses for sealing washers appears to be identical.

I put a steel straight edge longwise across the Manifold Hose block from port to port (above and below the tube protrusion) - it is not straight (i.e., center is convex & not perfectly flat) on the side that contacts the R-4, but is flat across the back where the steel tubes enter the hose block. The straight edge can "rock" at least 1/16th" on the sealing face, but cannot rock at all on the back side.

Just so I can rule the hose out, does anybody have a new or known good hose assembly handy, and could you put a straight edge across its sealing face? I would really like to know if this slightly convex sealing face is a stock configuration - my guess is yes. I don't think the thick manifold block could have ever been torqued down hard enough to deform it, and even if it was, I would expect both sides to be bent. I hate to replace the hose because I customized it to fit a parallel condenser, and it didn't leak before. I can't come up with another explanation for a leak, except for a compressor configuration difference I have failed to detect - so I'm now working on that. Thanks, Mack

I don't have any definitive info.... but I believe that the MB factory shop manual on climate control suggests putting a new manifold on when replacing the compressor... there are at least two reasons which come to my mind... one is that some of them have a filter in them which is not cleanable... so a black death at any point in your car's life might cause there to be a restriction there... or they found out that the manifold warps under the constant hydraulic pounding it gets and instead of saying they made it wrong they just post the procedure as ' requires replacement' ... Greg

That would be a pain in the wallet!!! That hose set costs about twice what a new compressor costs.

I have my a/c system torn apart right now. I'll check my manifold for flatness and advise. (It won't be today, though.)

Once again, I'm over-thinking a simple problem and missing the obvious. I had the wrong combo of sealing rings, after all. One Green and one Fat Yellow (Gold metallic) and it's good to go. I did measure all the compressor ports and they look to be within a few thousandths of each other, so I guess the #4354R4 is a good sub for the #4857. Thanks again, Mack

A new manifold hose on the left from Phil at Fastlane. Had to return it and Phil was not going to use the supplier anymore.

The right unit is the OEM Mercedes unit I took off the car. I had it rebuilt locally at a hydraulic shop here.

If your compressor failed, you need to replace the rubber section of the manifold hose or the metal particles will contaminate the system. Or replace the entire manifold/hose.

Dave

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__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

Might I ask how much that cost? Does "rebuilt" mean that the flexible section was replaced?

I will probably have to deal with this same issue when my new compressor arrives on Monday. I recall that others have reported similar issues with the new type sealing rings. My original compressor had simple o-rings. (It was still working after 24 years, but is being retired as a preventative measure.)

So, which color sealing ring goes where?

Green goes outboard, Fat Yellow goes inboard, toward the centerline. On mine, there is about 1 or 2 mm of Green edge visible between the R4 body and the manifold. Less of the Yellow is visible, perhaps .5mm. Mack

Okay, thanks. That might save me from the same predicament as you experienced.

Can't remember the exact amount. Somewhere around $60. They had to weld on a fitting and put on the new rubber section. It's been holding since last summer. Definately cheaper than a new Mercedes manifold hose and better quality then the aftermarket ones I've seen.

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

Thanks. Maybe I need to look for a hose shop.