I have a 1988 560 SEL in great shape but just learned that the wires to the air pump clutch were disconnected and buried from sight. Connecting them I found that the air pump was seized. Mercedes in Canada quoted me $1500.00 for a replacement. The car runs great without it, but I would like to restore it to mint. Can the pump be succussfully taken apart and rebuilt or unseized ?? I would appreciate an answer prior to removing it.

Assuming you are talking about the smog pump, you can buy a rebuilt one for less than $300 US (you have to send your old one back for rebuilding in exchange) and the installation is relatively simple -- two bolts and a hose. You may also need the related valves replaced (I did), which increases the parts price and labor a bit. I understand that if you do not replace the pump, you run the risk of a later expensive catalytic convertor job. See:

Smog Pump(I Think) disconnected

http://www.mbca.org/discussion/threadA.cfm?threadid=2897&state=General_Discussion&mysearch=smog%20pump

If the pump has seized, replace the check valves. One has usually failed and allowed hot exhaust gases to backflow into the pump and fried it.

Steve

Thanks for the info. I took my air pump out and it was rusted solid inside. The valves must be bad. I am ordering the new pump and valves as suggested. Thanks very much for the info in helping me decide what to do

My experience on my daughter's '88 420SEL was identical -- bad valves and pump rusted inside. Rebuilt pump has cured previous sins.

I had the same problem in my 420SEL. Had dealer replace all valves and hoses new, but replaced air pump with one from an auto grave yard of another 420SEL. Cost only $350 instead of $1500 (dealer quoted me the same price they quoted you).

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Jason Priest
1999 E430
1995 E420 - retired
1986 420SEL - retired

Did you notice any difference in engine performance or operation between new pump and old one??

No noticeable difference in performance other than the end of the 30-second loud screech on start-up of the car when the bad smnog pump tried to start up. My understanding is that the smog pump only operates until the catalytic convertor warms up and takes over, so I would think it is not a performance item.

Checked with Phil at Mercedes Shop and they don't show a listing for the two valves that should be changed with the pump. Does anyone know the Mercedes Part numbers for these two valves???? It would be appreciated. Oh, it's a 1988 560SEL Euro model ( been told that the valves for US models should be the same).