Vacuum boost pump (breather hose) and oil leaks
02-03-2005, 04:35 PM
#1
Audiworld Junior Member
Thread Starter
Join Date: Feb 2004
Posts: 65
Likes: 0
Received 0 Likes
on
0 Posts
Vacuum boost pump (breather hose) and oil leaks
Here is a real life story in case anyone has doubts about the faulty design of the vacuum boost pump which leads to failure of valve cover and camshaft adjuster seals:
I have a 2.8Q '99 A6 and about a week ago, on my way to work, smoke started coming form under the hood in massive quantities. It was so much that it got sucked into the ventilation system and filled the interior of the car. I stopped the car and with one look under the hood I could tell that it was oil leaking onto the exhaust on the passenger firewall side. I limped back home with the ventilation off and smoking so much it looked as if I was grilling hamburgers under the hood.
Having heard the stories about the vacuum boost pump (part number: 058 133 753 B) I disconnected it and determined that it was completely clogged on the side where the valve cover breather hose connects to it. I could neither blow any air in or out that side.
I reconnected the vacuum lines to it, but left the breather hose that comes from the valve covers disconnected and venting under the hood. The result: The massive oil leak stopped immediately, confirming that the blocked pump was causing back pressure to build up and blowing oil through teh seals.
Unfortunately the story does not have a completely happy ending. Even though the massive oil leak stopped, the damage was done and I had residual leaks from both valve covers and camshaft adjusters. I ended up having the valve cover and cam adjuster seals redone at my indy shop.
Currious fact: in order to release the replacement pump part to me indy shop, the dealer asked for a VIN number because they said there is a recall on these (I am not aware of any recall, but that's what my mecahnic was told).
We also cut up the old pump and found it completely gummed up and clogged. It is a very bad design because the passages are so small that they get blocked easily.
I have now put this part on 12 month 12,000 miles replacement schedule. It is easy to do (now that I replaced the calmps with regular hose clamps) and I rather spend the $30 bucks a year than risk another gasket blowout.
I would strongly suggest that folks test this pump. An easy way to do it is to just disconnect the valve cover breather hose at the pump (must cut off existing clamp and replace with regular hose clamp) and check for vacuum at the pump inlet. If no vacuum is felt, the pump is clogged.
I have a 2.8Q '99 A6 and about a week ago, on my way to work, smoke started coming form under the hood in massive quantities. It was so much that it got sucked into the ventilation system and filled the interior of the car. I stopped the car and with one look under the hood I could tell that it was oil leaking onto the exhaust on the passenger firewall side. I limped back home with the ventilation off and smoking so much it looked as if I was grilling hamburgers under the hood.
Having heard the stories about the vacuum boost pump (part number: 058 133 753 B) I disconnected it and determined that it was completely clogged on the side where the valve cover breather hose connects to it. I could neither blow any air in or out that side.
I reconnected the vacuum lines to it, but left the breather hose that comes from the valve covers disconnected and venting under the hood. The result: The massive oil leak stopped immediately, confirming that the blocked pump was causing back pressure to build up and blowing oil through teh seals.
Unfortunately the story does not have a completely happy ending. Even though the massive oil leak stopped, the damage was done and I had residual leaks from both valve covers and camshaft adjusters. I ended up having the valve cover and cam adjuster seals redone at my indy shop.
Currious fact: in order to release the replacement pump part to me indy shop, the dealer asked for a VIN number because they said there is a recall on these (I am not aware of any recall, but that's what my mecahnic was told).
We also cut up the old pump and found it completely gummed up and clogged. It is a very bad design because the passages are so small that they get blocked easily.
I have now put this part on 12 month 12,000 miles replacement schedule. It is easy to do (now that I replaced the calmps with regular hose clamps) and I rather spend the $30 bucks a year than risk another gasket blowout.
I would strongly suggest that folks test this pump. An easy way to do it is to just disconnect the valve cover breather hose at the pump (must cut off existing clamp and replace with regular hose clamp) and check for vacuum at the pump inlet. If no vacuum is felt, the pump is clogged.
02-03-2005, 05:29 PM
#4
New Member
Join Date: Nov 2004
Posts: 141
Likes: 0
Received 0 Likes
on
0 Posts
too bad the guy who broke that story was driven from AWA6 by overzelous Mods
just think how much he could add about clucthes, tires, even having AoA extend the warranty on transmissions for an extra 12/12
pity
pity
02-03-2005, 05:56 PM
#7
Audiworld Junior Member
Thread Starter
Join Date: Feb 2004
Posts: 65
Likes: 0
Received 0 Likes
on
0 Posts
It depends....
According to ETKA, the APB engine with the manual transmission does not have a booster pump. The APB engine with automatic transmission has a different pump (part # 078 133 701 L), I am not sure if this one is prone to the same problems.
The AHA, ATQ (2.8) and ART (4.2) all have the same pump (the one that is problematic).
The AHA, ATQ (2.8) and ART (4.2) all have the same pump (the one that is problematic).
