Oil dripping from vented oil cap

[RacerJo89]

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Has anybody else run into this problem? My 034 billet PCV valve seems to be in working order. Nothing else is raising red flags regarding too much positive crankcase pressure. I talked to one member and he couldn’t seem to resolve this issue with the vented cap so he went back to the non vented cap. I’m wondering what other experiences are out there regarding this.

[CELison]

I recently noticed some from my vented cap as well. Wiped it off and will see if it comes back. May have been from my recent oil change. I don't have the 2 streaks like you, It was 1 wide path of oil shine.

[Alex1188]

It's obviously leaking because the oil can is oreintated upside down. Lol

In all seriousness though I would check to ensure your pcv system is working properly.

[RacerJo89]

I recently noticed some from my vented cap as well. Wiped it off and will see if it comes back. May have been from my recent oil change. I don't have the 2 streaks like you, It was 1 wide path of oil shine.

I would definitely like to know if it comes back. This has been going on ever since I finished my build. Haven’t thought too much of it until my tuner said I should check into it. That pic was from a 30 minute drive with minimal boost. After driving 1000-1200 miles I noticed there isn’t enough to even make it pool on the lower lip of the valve cover. I can’t remember if my previous streak was one or multiple streaks. I had just wiped it off to see if it would return.

[RacerJo89]

It's obviously leaking because the oil can is oreintated upside down. Lol

In all seriousness though I would check to ensure your pcv system is working properly.

There are a few more tests I’m going to run to check the system. Searching all the leads I can!

[vavJETTAw36]

I originally had this problem. Thinking it was a faulty cap I bought OEM. The problem persisted. Thinking it was the mounting surface I tried sanding it smooth problem persisted.

I went back to unvented and have never had a problem. My pcv is completely healthy and brand new. It’s got two pcv valves for redundancy and a brand new PRV.

In my opinion, it’s just the oil slinging past the baffles onto the cap. Any bit of pressure and it leaks out.


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[RacerJo89]

I originally had this problem. Thinking it was a faulty cap I bought OEM. The problem persisted. Thinking it was the mounting surface I tried sanding it smooth problem persisted.

I went back to unvented and have never had a problem. My pcv is completely healthy and brand new. It’s got two pcv valves for redundancy and a brand new PRV.

In my opinion, it’s just the oil slinging past the baffles onto the cap. Any bit of pressure and it leaks out.


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You were the one “member” I was referring to. ;) But, thanks again Shawn! This info could be useful for other members as well.

[vavJETTAw36]

Lol didn’t read who the OP was. My bad.


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[christianb5s4]

The vented caps release pressure at under 1psi so it takes nearly nothing for them to leak. Now, I am not sure if it's good or bad to go with an un-vented cap since the vent is a safety feature to guard against the crankcase pressurizing.

[m_haiser]

personally id rather wipe off a valve cover once in a while than replace VCGs and what not from excessive crank case pressure

[RacerJo89]

personally id rather wipe off a valve cover once in a while than replace VCGs and what not from excessive crank case pressure

I’m right there with ya. My engine bay didn’t stay clean for long anyways!

[RacerJo89]

The vented caps release pressure at under 1psi so it takes nearly nothing for them to leak. Now, I am not sure if it's good or bad to go with an un-vented cap since the vent is a safety feature to guard against the crankcase pressurizing.

Do you have one on your car?

[m_haiser]

I’m right there with ya. My engine bay didn’t stay clean for long anyways!

mine doesn't either, I drive my car far more often than I detail it

[CELison]

Wiped the oil off a few days ago, did a couple 2-3 pulls today and checked. No oil anywhere around the cap. For a built motor Im impressed. Burns basically no oil and doesn’t have blowby issues. Nice work Zillarob.

[RacerJo89]

Wiped the oil off a few days ago, did a couple 2-3 pulls today and checked. No oil anywhere around the cap. For a built motor Im impressed. Burns basically no oil and doesn’t have blowby issues. Nice work Zillarob.

Hm. Interesting. Thanks for getting back to me! Glad your car is running tip top. At least I got over the green oil swamp thing...haha

[CELison]

Haha yeah I remember that. How’s the car running? It takes a while to dial a car in after a complete overhaul like a motor build. Oh and get rid of those shitty worm clamps on your cooling system! Fuel injection clamps work great if you don't want to run the oem spring clamps.

[christianb5s4]

I swear, every other day the quote and multi-quote option stops working for me. Anyway.

RacerJo: I only ever experienced oil out of the cap during 1/2 mile runs, but that 's like due to the vented catch can I was running diluting the amount of vacuum through the spider hose to properly relieve crank case pressure under boost. I sealed the catch can so will see if the same issue occurs at the next 1/2 mile event in November.

For street driving, 1/8th, 1/4 mile and roll racing, while there's some oil film around the cap area it's definitely nothing to be worried about.

[vavJETTAw36]

For me hitting full boost several times would be enough for oil to run onto the exhaust manifold. I’d rather blow a VC in the near future than to lose brain cells breathing in burnt oil fumes.


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[RacerJo89]

Haha yeah I remember that. How’s the car running? It takes a while to dial a car in after a complete overhaul like a motor build. Oh and get rid of those shitty worm clamps on your cooling system! Fuel injection clamps work great if you don't want to run the oem spring clamps.

The car has been good! Still dialing it in and working through the bugs. Weeding through the nuances of the new motor have been...challenging. I had to put those worm drive clamps on because the spring band clamps have proven to be tired and those coolant hoses were leaking all over my valve covers. Trust me when I say they are near the top of my to-do list. Haha. I’ll look into those fuel injection clamps. Pretty sure I have a few lying around. Thanks for the tip.

[vavJETTAw36]

The car has been good! Still dialing it in and working through the bugs. Weeding through the nuances of the new motor have been...challenging. I had to put those worm drive clamps on because the spring band clamps have proven to be tired and those coolant hoses were leaking all over my valve covers. Trust me when I say they are near the top of my to-do list. Haha. I’ll look into those fuel injection clamps. Pretty sure I have a few lying around. Thanks for the tip.

That’s mostly what I use as well. If it’s something I know I’ll never touch again I’ll use the crimp style camps like factory.


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[jjvwg]

Having this issue myself on my recently refreshed motor. Is there a way to check if the PCV system is working correctly? I have a brand new OEM spider hose assembly (latest revision) and I have oil leaking from oil cap area. I know on the 1.8 you would loosen the oil cap while the car was idling and see how it reacted, with the desired result being the cap dancing around on the valve cover and and not being blown off/sucked down. I tried this two days ago on the 2.7 and it seemed like nothing happened...no dancing, no suction, no positive pressure coming from full hole. Been a while since I’ve done this, but I noticed that if I run the car with the PRV valve disconnected from the y-pipe that I remember having a steady stream of airflow coming out of it that would be pushed into back into the intake. Should that be a steady stream? Any thoughts/ideas would be appreciated, thanks guys.


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[blitz2190]

i just vent my catch can into two venturi's in the exhaust, seems to work well and pull enough vacuum to have dry valve cover gaskets, and suck water/oil sludge when I forgot to empty it once(scared the hell out of me with the smokescreen), no vented cap needed, and the hot exhaust burns the vapor, and I get way less buildup in my intake now.

[m_haiser]

I like that idea

[christianb5s4]

Blitz, do you just have one line off the catch can into a bung in the exhaust? Any pictures?

[blitz2190]

yeah just one line, I don't have any pics left as I broke the phone from when I did this, but is simple, just set up a catch can as usual and run the outlet line to two of these (T'd together for constant vacuum) in each downpipe after the cats(absolute must otherwise you'll clog your cats). I made my own venturi nipples but can just as easily buy them. not sure if its necessary but I also used two 1 foot sections of silicon hose to connect to the nipples for the high heat, then used regular rubber line te rest of the way to the catch can.