I'm going to be selling my 1998 A4 2.8 QMS and am trying to get a few things up to snuff. I'm going to be checking my PCV system with its suction pump and hoses for buildup that may be causing my chronic oil leaks even after VC gaskets and various seals were replaced about 10K miles ago. I realize these PCV components especially the hoses are fragile at this point but I'd like to try cleaning them first to save on cost of new parts. Does the cleaning work fairly well on all or some of the parts? Is removal of the parts for cleaning/replacement fairly straightforward or are there instructions somewhere to follow? Thanks for any tips.

 

This job is going to be a PITA, I'm sorry to say. The suction pump and the various hoses attached to it are in the very rear of the engine, underneath a bunch of vacuum hoses. Worse, the big long breather hose - which runs from the front left of the engine across to the right then back to the right rear - ends up attached to the engine block below the throttle body. It is a major PITA to get to. If you can take the throttle body assembly off you will be able to get at it much easier.

I ended up replacing all of the rigid breather hoses and the pumps that came in a nice kit I got at Blauparts.

Also, you'll probably run into some "one use" Audi stock hose clamps, which you should cut off with a wire cutters. Don't even try to slip them off. So make sure to plan ahead and get some new regular hose clamps with the screws.

I don't envy you doing this job. I can't think of anything good about doing it, other than when I got done I vowed I would never do it again. My breather system was completely plugged, so I'm glad I did it. But if I ever needed it done again I would gladly pay my Audi mechanic to do it.

Good luck, you'll need lots of patience and persistence to do this job.

 

Thanks for the encouragement! LOL. Anyway, I checked the plastic hose connected to the driver's side valve cover as suggested by Blauparts and there didn't seem to be any evidence of sludge buildup. I then was able to remove the suction pump - held in with replacement hose clamps so it's been off before. I can blow through the main tube freely from the end closest to the angled smaller tube but air won't go in the other direction which I think is correct. However, I cannot blow or suck from the small side tube. Should it be that way or is it a sign that it's clogged?

The greenish check valve just below the suction pump still has the original Audi clips so I doubt it's ever been changed. I'll try that next.

 

I was able to find a new OEM PCV for $20 on eBay and the ribbed plastic hose kit for $55. It's a PITA to switch out the hoses near the throttle body, but doable.

FYI I attempted to clean my PCV and hoses with carb cleaner to no avail. I doubt you would be able to clear the crud out of either.