Rear Crank Seal Pushed/Blown out of Flange after 600 Miles - PCV Question

[LINDW4LL]

I just had my recently replaced rear main seal get pushed out of the flange 600 miles after installing and want to make sure I rule out any crankcase ventilation issues that may have contributed. I have the late-style PCV (MY2002). So far I've verified that the check valve between the spider hose collector and intake manifold is functioning properly, and I can blow through the other hoses of the spider hose assembly without obstruction.

Are there any other PCV components I'm missing that I should check? I've also considered that it may have just been an out of tolerance Corteco flange/seal. I'm dubious, but the original seal wasn't leaking when removed (and I'd already put on 4,500 miles of stage 3 at time of replacement).

[Teck09]

I am assuming you're running the stock plastic PCV? I too have the late style manifold and spider assembly and originally rebuilt my spider hose using the stock PCV. However, after checking it on several different occasions I replaced it with a metal one I purchased here ---> https://www.ebay.com/itm/UPR-12MM-No...97.m4902.l9144 The reason for doing so is that the stock PCV valve would work intermittently. Sometimes it would hold pressure, sometimes not. I didn't want to risk it so I just went the other route. I know this doesn't exactly answer your question but just something to think about.

[christianb5s4]

I ran one of those spring type rear main seals and needless to say, I switched back to an Audi/VW OE one. Some have good luck with those and some don't but I didn't want to risk it and went with the original style RMS.

I'd imagine if you had such a severe crankcase ventilation issues to where your RMS blew out, your valvecover gaskets/cam caps etc. would have given up the ghost well before a RMS.

[LINDW4LL]

I am assuming you're running the stock plastic PCV?

I sure am. Wasn't aware a check valve could fail intermittently, but sounds like a good idea to replace given the age, even if preventatively. Appreciate the link!

I ran one of those spring type rear main seals and needless to say, I switched back to an Audi/VW OE one. Some have good luck with those and some don't but I didn't want to risk it and went with the original style RMS.

I'd imagine if you had such a severe crankcase ventilation issues to where your RMS blew out, your valvecover gaskets/cam caps etc. would have given up the ghost well before a RMS.

The Corteco flange/seal uses an OE style PTFE seal- looks identical to stock. I figured they were probably the OE manufacturer since it's the only unit available besides genuine, but lesson learned.

Tend to agree on the second point. No leaks elsewhere.

[skree25]

What about the breather in the valley under the IM. You could have a clog in the gasket that would cause your issues before ever reaching PCV system


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[TylerT]

I ran one of those spring type rear main seals and needless to say, I switched back to an Audi/VW OE one. Some have good luck with those and some don't but I didn't want to risk it and went with the original style RMS.

I'd imagine if you had such a severe crankcase ventilation issues to where your RMS blew out, your valvecover gaskets/cam caps etc. would have given up the ghost well before a RMS.

+1.

I don't know for how long, maybe ~200 miles or so, my PCV system failed and the first thing I noticed was a A LOT of oil buildup in the bottom of the intercoolers / periodic puffs of white smoke under WOT. As I understand it, the increase in crankcase pressure wouldn't allow the oil to to circulate through the turbos & also contributed to excessive blowby.

I was really lucky, my cam seals / valve cover gaskets / my newly installed RMS stayed intact.

Sounds like the RMS failed prematurely.

[LINDW4LL]

Yep, that explains the sudden leak







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[Teck09]

^^ That is nuts. The one time you WISH the cam seals would have blown.

I can't take full credit for the PCV valve link but hope it works out for you, vavJETTAw36 put me onto it initially.

[christianb5s4]

Ohhh boy, I've heard of failures like that on the spring type RMS which is why I took mine out and replaced with an OEM one even though they're harder/more expensive to find. Bummer yours failed so soon and it looks like the PCV had nothing to do with it.

[vavJETTAw36]

^^ That is nuts. The one time you WISH the cam seals would have blown.

I can't take full credit for the PCV valve link but hope it works out for you, vavJETTAw36 put me onto it initially.

So an update on that pcv valve. The orffice on the inside is way too large and it draws too much vacuum on the CC. This was apparent when trying to remove the oil cap and the vacuum was holding it down. This can damage our front main and rear main seals. I temporarily pinched off that spider leg to limit vacuum until I could come up with a solution.

So what I did was retain that pcv but also reinstalled the leaky 034 one to limit vacuum. Additionally, I utilize the vented oil cap in case I get any built up pressure. However, this vented cap leaks a bit of oil periodically and I am not sure why. I believe the cams just throw oil up onto the vent and the slightest pressure pushes some out. I may end up going ventless or building my own vented cap with a line that runs away from the manifolds so I don’t smell burning oil lol.




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[Teck09]

So an update on that pcv valve. The orffice on the inside is way too large and it draws too much vacuum on the CC. This was apparent when trying to remove the oil cap and the vacuum was holding it down. This can damage our front main and rear main seals. I temporarily pinched off that spider leg to limit vacuum until I could come up with a solution.

So what I did was retain that pcv but also reinstalled the leaky 034 one to limit vacuum. Additionally, I utilize the vented oil cap in case I get any built up pressure. However, this vented cap leaks a bit of oil periodically and I am not sure why. I believe the cams just throw oil up onto the vent and the slightest pressure pushes some out. I may end up going ventless or building my own vented cap with a line that runs away from the manifolds so I don’t smell burning oil lol.




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Sounds like it may have helped to hold OP's rear main in place lol

Seriously though, thanks for the update. I am a bit bummed to hear that however. If I experience the same problem I have an idea for a solution that I will try out. On my motorcycle's crankcase breather there is a reducer inserted into the breather outlet. Essentially it is a small piece of tubing with an OD the same as the breather's ID, the hose then has a reduced ID effectively limiting the flow. You could theoretically "tune" the vacuum by changing the hose with different ID's.

[Alex1188]

So an update on that pcv valve. The orffice on the inside is way too large and it draws too much vacuum on the CC. This was apparent when trying to remove the oil cap and the vacuum was holding it down. This can damage our front main and rear main seals. I temporarily pinched off that spider leg to limit vacuum until I could come up with a solution.

So what I did was retain that pcv but also reinstalled the leaky 034 one to limit vacuum. Additionally, I utilize the vented oil cap in case I get any built up pressure. However, this vented cap leaks a bit of oil periodically and I am not sure why. I believe the cams just throw oil up onto the vent and the slightest pressure pushes some out. I may end up going ventless or building my own vented cap with a line that runs away from the manifolds so I don’t smell burning oil lol.




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What's this part your talking about being to large? I recently redid my pcv system with the larger 25mm hockey puck valve and feel like it is drawing to much on the crankcase. Mind sharing the link that was talked about above?

[Teck09]

What's this part your talking about being to large? I recently redid my pcv system with the larger 25mm hockey puck valve and feel like it is drawing to much on the crankcase. Mind sharing the link that was talked about above?

It is reference to the PCV valve that I linked above. You're speaking about the PRV that attaches to the Y-Pipe.

[Alex1188]

It is reference to the PCV valve that I linked above. You're speaking about the PRV that attaches to the Y-Pipe.

Ahh gotcha. Must have missed that. Ya I went with the 034 spider hose kit as I didn't want to mess with cutting and what not, wanted PNP. But when I did so I went with the updated 06A129101F 25mm PRV and now I notice more oil mist being drawn through it. So I'm thinking of going back to 06A129101D 19mm PRV instead and see if the size changes anything.

The 034 billet PCV seems to be working fine tho. Not sure why others have said they had issues with them. I know there was a period back a couple years that there was a design change or revision of some sort.

[vavJETTAw36]

Ahh gotcha. Must have missed that. Ya I went with the 034 spider hose kit as I didn't want to mess with cutting and what not, wanted PNP. But when I did so I went with the updated 06A129101F 25mm PRV and now I notice more oil mist being drawn through it. So I'm thinking of going back to 06A129101D 19mm PRV instead and see if the size changes anything.

The 034 billet PCV seems to be working fine tho. Not sure why others have said they had issues with them. I know there was a period back a couple years that there was a design change or revision of some sort.

It’s not really a part issue. The part works fine but intermittently you may get some debris that lodged between the ball valve and the orfice allowing pressure to pass by. A quick blow or spray with silicone spray will clear it up until the next time it happens.

I don’t know that the factory valve has the same problem or not. What the system really needs is an inline filter or screen to catch debris.


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[Alex1188]

It’s not really a part issue. The part works fine but intermittently you may get some debris that lodged between the ball valve and the orfice allowing pressure to pass by. A quick blow or spray with silicone spray will clear it up until the next time it happens.

I don’t know that the factory valve has the same problem or not. What the system really needs is an inline filter or screen to catch debris.


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What size PRV are you using? or did you delete it all together when you put in the CC?

[vavJETTAw36]

What size PRV are you using? or did you delete it all together when you put in the CC?

I am running the 19mm 1.8t PRV. The s4 is 17mm and shouldn’t have any affect on the vacuum you’re pulling. The PRV simply regulates how much vacuum can be pulled by way of intake, but works in reverse with no restrictions.


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[Alex1188]

I am running the 19mm 1.8t PRV. The s4 is 17mm and shouldn’t have any affect on the vacuum you’re pulling. The PRV simply regulates how much vacuum can be pulled by way of intake, but works in reverse with no restrictions.


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You by chance have the part number of the PRV your using? I wasnt aware that the stock PRV was 17MM (Any clue of this part number?). The part numbers ive seen are...

06A129101D = 19mm

06A129101F = 25mm with metal internal tube

[christianb5s4]

Do what I did, add a catch can. I've done a few different spider hose/PCV setups and the one that works the best is stock setup with good PCV components and an integrated (high quality) catch can.