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View Full Version : Does this sound like the symptoms to a leaking valve cover gasket?



WonPointAteTea
10-15-2010, 09:13 PM
Car: 2000 atw 1.8t chipped 120k miles

I just noticed that I am close to 3k miles since my last oil change and it was down about 3/4 a quart, so i topped it off to get me through until the weekend rolls around to change it.

I am driving it down the freeway cruising along pretty good for about an hour, stop off at a rest station and notice there is a "burning brake" smell and then i notice a little white smoke coming from my hood. I pop the hood but the smoke is gone. Brakes are completely cool to the touch, so I start the car, no smoke. So i continue driving normal and pull over after 35 miles and its doing the same thing, this time its smoking much much more, and i can tell its coming from the rear area behind the cylinder head it seems, but i cannot pinpoint it. The highway i was on was full of big mountain passes so I was in and out of boost a lot during some of the climb. I babied the car the next 50 miles to my destination and i get out and there is a very very very faint smell but nowhere near what it was before and absolutely no smoke.

I take the car around the block and get into the boost to see if the smell and smoke will return, the smell gets a little stronger but no smoke.

Does this sound like i just blew out the valve cover gasket? Maybe it has been blown and topping off the oil made is noticeable somehow? and also is there a PCV system on a 2000 that might be clogged? I have read others talking about how clogged PCV systems getting clogged can lead to blown gaskets, but does the 2000 atw have a PCV system? if so where is it and whats the offending part? The car still ran great, no weird driving issues, pulled strong, just the smell and the smoke.

So I am looking for some input here.

Also i had read that the cam tensioner gasket is a PITA to change, any reason to believe this might be the issue over the valve cover gasket, or any way to rule one versus the other?

Thanks!!!

walky_talky20
10-15-2010, 10:01 PM
VC Gasket seems plausible. You can pretty much see if it is leaking by looking at the lower edge near the exhaust manifold. That is where it normally leaks. You can also pull out the coil packs to see if any of the plug holes are filling with oil. That is a definite sign of the vc gasket being bad.

You can check to see if your cam chain tensioner gasket is leaking by looking at the back of th head. A mirror will help. You are basically looking to see if lots of oil is rinsing down the back of the head from tensioner area. You can use your mirror to look right into the semi-circle hole where the half-moon plug sits. That is where the main CCT gasket oil leak situation happens. It would be the red circle in this photo:

http://i19.photobucket.com/albums/b154/walky_talky20/1-8T-gaskets.jpg

If it were me, I'd just do both at once. That way you can be done with the oil leaks from the top end for a while.

WonPointAteTea
10-15-2010, 10:48 PM
thanks for the pic! is there a pcv system for the 2000? i am trying to figure out why this only seemed to happen on the uphill constant boosting portion of my trip then nothing on the last stretch of easy downhill road

walky_talky20
10-16-2010, 09:47 AM
Well, the seals are in the rear of the motor, so that may have something to do with it, lol.

The 2000 1.8T (engine code ATW) certainly does have a PCV system. And they aren't without problems either. There are really 2 halves of the system. Part of it works under vacuum and the other part under boost. I'll try and keep this is as complete and simple as possible. We'll go with a list format and see how that works. Please follow the links to see the items:

- Crankcase vapors exit the engine at the top of the oil filter housing through a squiggly looking plastic "breather pipe":
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Breather_Hoses/ES2070633/
- This pipe connects to a rubber "T" hose:
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Breather_Hoses/ES258895/
- One of the "legs" of the T has a PCV "breather valve" stuffed inside of it:
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Breather_Hoses/ES2093820/
- That valve connects to an "S" shaped rubber hose:
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Breather_Hoses/ES6120/
- The other end of the S hose connects to the smallest port of the "Suction jet pump" (aka "SJP"):
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Breather_Hoses/ES1891983/
* The suction jet pump basically sits in-line between the intake manifold and the brake booster. The 3rd, smaller port provides the vacuum source to the PCV valve.
- The suction jet pump finally connects through this "L" shaped hose, directly to the intake manifold:
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Breather_Hoses/ES251440/
- Back to the rubber "T". The other "leg" connects to a metal hard line that runs all the way around to the turbo inlet pipe (TIP). At the TIP, it connects through the Pressure Regulative Valve (PRV):
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Search/Pressure_Regulative_Valve/ES261091/

So the synopsis of how this tragedy works:
- During vacuum the PRV in the TIP is closed. There is a very small hole in it where fresh air can enter the crankcase vent system. Vacuum is provided to the crankcase through the PCV breather valve, which regulates the supplied vacuum. So the flow goes out of the plastic crankcase breather pipe, into the "T", through the PCV breather valve, through the "S" hose, through the suction jet pump, through the "L" hose and into the intake. That is during vacuum.
- During boost, pressure from the manifold is applied through the "L" hose, through the SJP, through the "S" hose and to the PCV breather valve. This pressure actually closes the breather valve so turbo boost pressure cannot enter the crankcase.
- Meanwhile (still during boost), the only vacuum/suction source here is in the turbo inlet pipe. As the crankcase pressure rises, and the (slight) vacuum in the TIP rises, the PRV is forced open allowing the crankcase vapors to flow: from the plastic crankcase breather pipe, into the "T", into the metal hard pipe, into the PRV, and then dumped into the TIP, pre-turbo.

So that's how it works. Common failure points are:
- small port on suction jet pump clogged
- PCV breather valve clogged or stuck open
- plastic breather pipe cracked wide open
- rubber "T" and rubber hoses cracked or otherwise deteriorating

As you can imagine, the first 2 failures are pretty bad. With a clogged SJP, no vacuum is ever applied to the crankcase. Same with a clogged breather valve. This can cause the crankcase pressure to get too high and will cause oil to be pushed past the seals (which may be your problem) If the breather valve is stuck open (usually by some coked oil deposits) boost pressure will enter the crankcase. That is not good either and will cause oil to be pushed past the seals (which may be your problem). So you should check out those common failure points.

WonPointAteTea
10-16-2010, 10:15 AM
ALL HAIL WALKY_TALKY20 lol thanks for the VERY informative post! I dont think the breather valve to be at fault as i just replaced it along with the rubber s hose less than 8 months ago. But i am going to pull the SJP out as well as try to get a look at the lower plastic crankcase breather hose, i have always seen people mention this but could never see it down there.

Thanks again! I was able to look at the back of the head with a mirror and thankfully the CCT gasket showed no signs of oil around it. the vc gasket is pretty dirty around the edges so it was hard to sell if anything was fresh or not, but this could be from leaking over time. So i wiped it all down so i could see if anything new has started but i have not driven it yet today.

Thanks again, i'll keep you posted!