05SilverA8

About 2-3 weeks ago my compressor made a sound like a magnet fell off the unit, or something was making a lot of bad sounding noise. This lasted for a few minutes and then went away and did not come back. No Yellow/Green lights or error codes. Today I turned the car off and the compressor motor kept going with a loud grinding sound. The motor sounded really bad and kept making a clicking sound drawing a lot of current from the battery when the car was OFF. There was also a really bad smell like a wire was burning. I figured that this was the DEATH of the WABCO when the yellow and green lights came on. The unit finally stopped making noise and about 30 minutes later the lights went out and all seems fine with the compressor. I know I have limited life left in the unit.

Has anyone tried this rebuild kit?

Has anyone retrofitted a Mercedes WABCO unit? They seem to be about half the cost of the other units.

ltooz_a6_a8_q7

Hello Mark,
For $42, you should try the rebuild kit to see if it works. About the Mercedes pump, if the wiring harness fits and the capacity is the same, it should work. Where do you see the mercedes version?

05SilverA8

Look on eBay for Mercedes WABCO. They are about half the price and it looks almost like the same pump (I have seen posts that you need to swap temperature sensor, intake hoses and electrical plug). This in no way seems the $250 in pricing difference.

Look Here

Instructions for replacement do not look that bad: PISTONFIX

ltooz_a6_a8_q7

When my pump make noises pumping, I'll get the piston kit, if it doesn't work, I'll get the Mercedes pump to try. The only problem is I can't see all the connections on the Mercedes part. Anywho, document what's you're doing to fix yours.

Come to think of the $600 pump - every 100k miles is not bad.

Cheers,

Louis

05SilverA8

Sounds like the most economical solution. What is strange is the unit is working PERFECTLY today, no noises, all normal.

Sounds like the piston is getting hung up at certain times, so a new piston ring would most likely resolve issue. And yes, $600 for a pump every 100K miles is not that bad.

bmwm750

All things wear sooner or later.... however, if the Mercedes part can be made to work for half the cost, that's even better!

dvs_dave

The piston ring repair is one thing, but can the loose motor magnet be easily repaired? Does it just need to be stuck back in place and it's good to go, or is it more involved than that?

05SilverA8

From what I have heard previously, you just epoxy them back on. I will order the new piston sleeve, and put that on along with re-attaching the magnets with some super strong epoxy.

Mister Bally

The Mercedes unit has different connectors. No big deal. Splice in the ones from the bad unit. There are differences in internal valving and flow rates. Nothing to be concerned about.

bmwm750

Good to know for the future