can a bad PCV cause intercooler damage?

[JDsleeper]

Hi everyone, I've owned a 2007 A4 2.0t for about 5 years now and it's recently started having issues. I just took it out for summer and it was running really bad, almost stalled whenever I gave it gas but idled okay with a slight hiccup every few mins, but would pull itself back. It had a check engine light so I bought a logger and pulled a coolant performance code (2181) and nothing else. I went through and did tune up stuff, plugs, coil check, fuel check, air filters etc, still couldn't give it gas.

I bought torque pro just to get some logs and found that anytime it went from closed loop to open loop was when it would show symptoms. Everything else seemed fine except for some smoke seemingly coming from the exhaust manifold and a ticking that I thought was lifter tick from my time with DSM's. I went to take the oil cap off and listen to if it was coming from inside the valve cover for sure and when I tried the suction was so high it nearly pulled the oil cap out of my hand and the car immediately started running super rough, nearly stalling. I worried it might be a head gasket issue at this point and took it to Audi.

I got a call this morning saying the valve cover is bad, I really don't know what that means, but ok, as well as a bad thermostat (2181 I assume) and the intercooler needs to be replaced. They all seemed like separate issues, but I was wondering how a leaky/bad valve cover would allow the type of vacuum that pulls an oil cap out of my hand and whistles when removed. Torque logged my vacuum between 18-21 inhg at idle and didn't show any spikes or dips, though that may just be what the computer thought.

I did some research since then and saw a few people talking about how a defective PCV that was under recall, and how it can cause the valve cover to leak oil into the turbo causing blowby. My intercooler definitely has oil in it, and I was burning through about a quart of oil every 2500 miles. Does this sound like a defective PCV problem more then a valve cover issue as the dealer says? They never mentioned the PCV on the phone, but I can do all the repairs myself if it's just a valve cover, thermostat, and intercooler, I just worry they are trying to get some paid business before replacing the PCV under recall, and that if I take the car home and replace the parts the problem will return because the PCV is actually defective. Any advice for me in this situation?

[mtroxel]

The valve cover is part of the PCV system on this motor. It has check valves in it. That could cause your excess vacuum, and could eat up your boost. But I would think you'd get an underboost code(p0299). I'd pay attention. If you have boost leaking into the crankcase through the VC, you could blow out some seals. They're not designed for that kind of pressure.

My intercooler definitely has oil in it, and I was burning through about a quart of oil every 2500 miles.

All intercoolers have some oil in them. Every time I change oil I remove the bottom driver's side boost hose and about an ounce comes out. I burn 0 oil between changes. If no one has ever drained yours, it makes sense you have more that I see.

[JDsleeper]

so it may just need to be drained, not completely replaced if oil is the issue?

There's only one Audi dealership around so I'm kind of at their will when it comes to getting recall and service bulletin work done. I really think it's a PCV issue which should be replaced for free, but they want the valve cover and intercooler work to do it. That's nearly a grand of work I can do myself just to get them to do their job. They also refuse to replace the airbags even though I got the recall notice, just keep saying not yet.

[wding2000]

Oil filler cap suction definitely points to bad PCV. VC might be bad as well. But I would start by replacing PCV first (cheapest) and see before replacing VC.

[mtroxel]

I really think it's a PCV issue which should be replaced for free, but they want the valve cover and intercooler work to do it.

Yes, it does sound like a PCV issue. But the PCV system is not just one valve. The valve cover is part of it. There's a pretty good tutorial around here somewhere that explains it all and I can't find it. There are two check valves in the valve cover, and if any of the passages leak (it happens) or a check valve is toast, your PCV system is FUBAR, even if you had a brand new PCV valve. If you had an early version of the PCV valve and breather tube, I'm assuming the dealer would love to have Audi pay them to do the work. If you think of your PCV system as one valve stuck on the side of the valve cover, you are way off base.

[JDsleeper]

that's basically how I was thinking of it. This is my first Audi, my idea of a PCV is a $10 ball and spring that screws into the valve cover and dumps in a catch can. I've been looking into it, and it does seem far more elaborate setup then in used to, but not too bad to replace outright.

Is there any way to check the valve cover to see if it's faulty? They were just going to replace the gasket, not the whole cover but I don't want to assume the cover isn't bad if I can help it. I'm ordering the PCV, valve cover gaskets, and thermostat tonight and just want to make sure there isn't some other preventative maintenance I can do while I'm in there. Also should the valve cover screws be replaced when taking the cover off or can they be reused.

[mtroxel]

that's basically how I was thinking of it. This is my first Audi, my idea of a PCV is a $10 ball and spring that screws into the valve cover and dumps in a catch can. I've been looking into it, and it does seem far more elaborate setup then in used to, but not too bad to replace outright.

Is there any way to check the valve cover to see if it's faulty? They were just going to replace the gasket, not the whole cover but I don't want to assume the cover isn't bad if I can help it. I'm ordering the PCV, valve cover gaskets, and thermostat tonight and just want to make sure there isn't some other preventative maintenance I can do while I'm in there. Also should the valve cover screws be replaced when taking the cover off or can they be reused.

I'm not sure how to check the valve cover. If you search around you'll see some pics guys have taken after removal when it was obvious the little passages had broken open. But I do not know how to test it.

Have you seen that if you get a new revision of the PCV valve you also need the new revision of the breather valve? You'll see it talked about at most good parts web sites. I did the valve cover gasket about 30,000 miles ago. Re-used the bolts, they're only about 7 ft/lb bolts so they're no big deal. But as any gasket surface, uniform torque does matter so I'd pay attention to that.

[JDsleeper]

I was just going to order the parts from ECS, but I don't know about the PCV and breather thing, so I'll look into it. Probably should just call them tomorrow just to make sure.

[pezgoon]

Only way to test it is to swap with a good one, generally you will see obvious damage, but some people have reported no visible issues (issues were inside the passages) and only way to know was they replaced it and stopped going through oil (and the suction thing)


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[Low and Behold]

1. There are no check valves inside the valve cover. The VC simply has passageways for air to travel (one direction while under boost, the other while in vacuum)

2. The VC can be tested by removing it and inspecting for cracks and/or blowing through the passage ways while plugging one side to make sure it holds air. If there is a crack in the seam, oil thats being tossed around the crank case will get sucked through it. This oil then enters the VC air passageways, makes its way into the turbo, and usually settles at the lowest point in the system (intercooler).

3. The two Check Valves are located in the PCV and Breather hose themselves, not the VC

4. Early B7s only had a check valve (1) in the top PCV, while the breather hose was just a metal hose with no check valve. Nowadays if you buy the latest revisions, they will BOTH have check valves, bringing the grand total to TWO check valves for the system. A smaller faction of people are under the assumption that there is only supposed to be one check valve in the entire system (either in top PCV or breather hose), but the latest revisions have one in each.

Where are people getting information that the VC itself has check valves in it? Im genuinely curious.

Just wanted to throw these points out there. OP - id start with changing the PCVs to the latest revisions. Easy to replace, and relatively cheap. You can pull your VC and check it yourself. Ive been through two VCs (one was used that i borrowed from a friend) and its pretty clear when one of them is busted. In fact, once I forked out the money for a brand new one, my oil consumption went from 700 miles/qt, to nothing.

[JDsleeper]

So as long as the breather kit has a check valve in the breather tube as well as the PCV itself that's the newest revision?

Also one last question. If I'm replacing the PCV and VC gaskets should I replace the vapor canister as well? I honestly have no idea what it does, but it looks like part of the overall setup.

Thanks for all the help everyone.

[Low and Behold]

So as long as the breather kit has a check valve in the breather tube as well as the PCV itself that's the newest revision?

Also one last question. If I'm replacing the PCV and VC gaskets should I replace the vapor canister as well? I honestly have no idea what it does, but it looks like part of the overall setup.

Thanks for all the help everyone.

This is what you want https://www.ecstuning.com/b-genuine-...kit/06f198206/

Im not sure if they've done multiple revisions with check valves, but these are the latest ones.

For the charcoal canister, I'd say no. The PCVs are the problem pieces.

[mtroxel]

1. There are no check valves inside the valve cover. The VC simply has passageways for air to travel (one direction while under boost, the other while in vacuum)


3. The two Check Valves are located in the PCV and Breather hose themselves, not the VC

Your right. The check valves are on either side of the VC, not actually in the VC.