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Oil coming from Oil Fill Cap

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DSM Chase

DSM Chase

10+ Year Contributor
778
51
Sep 19, 2011
Senoia, Georgia
I have tried using two different oil caps that i know do not leak from our other dsms... No visable cracks on the valve cover and its definitely coming from the cap. Seems to be a boost related issue, to much crank pressure? Whats crazy is its not blowing out the dip stick.

Any ideas?
 
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Yeah, sounds like too much crankcase pressure. What are you using for crankcase ventilation?
 
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Then check the PCV valve. It could be clogged or leaking boost into the engine.
 
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I had a similar problem. But I'm not sure if the problem lies else where.
It was blowing oil through my oil cap sometime ago. I bought a new oem pcv from stm. It was still blowing through the pcv? or it was blowing in from somewhere else, I don't know.

Now I'm running a check valve before the pcv and it stop. But to me it seems like a band aid.
 
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boost97gst said:
Put in a check valve in the pcv to mani line. Fixed my leaking instantly
Click to expand...
Check valve? And Do you mean put it in the line from the PCV to the Intake Manifold?
 
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Black-98-Gst said:
I thought it was somewhat common for the stock caps to leak?

I've always used an evo cap with 2 gaskets, never have any problems with leaks.
Click to expand...

Try this first. I also had to double up on the rubber gasket on my oil cap.
 
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Thing about this is, (assuming the motor is in good working condition), if the gasket on the cap is good, it should not leak. If the dipstick is good, it should not pop out. If the above two items are in even half way good shape AND the PCV system is fully functional and set up properly for the needs of the setup, you should never pop a stick or push oil out of the cap, and if you do experience these things and do everything in your power to stop them from happening without first addressing the root cause of the issue, the excess pressure is just going to find the next easiest place to go, which is front and rear main seals and camshaft oil seals, amongst other things.
 
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This cap leak issue happened to my talon as well. All I did is went to habor frieght. Bought a gasket kit that had a diameter the same size as my cap. Place it and bam leaked stopped. Basically like others had said double gasket. You tried other caps but it could that even tho your cap is on right and tight is still not vac type locking so the oil still comes out.
 
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As everyone is stating you have a positive crankcase pressure problem. Easily solved getting a new PCV valve or as another member mentioned using a "one way valve", that will seal better then the stock PCV valve. If you want to try you can remove the stock PCV valve, install a regular hollow barbed fitting and then a brake booster one way valve. It should solve your problem.
The other only problem I can see is if your engine is tired you'll have a lot of blow by causing this symptom too.
Regards,

TRILOGY TURBOS
 
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It took me 3 valve covers to resolve this problem with my current gsx. I couldnt find a leak to save my life but after finding a good working valve cover it ended up being a crack in the corner of the valve cover not very visable until it was torque'd down.
 
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While doubling the gasket on the cap seems to be a good idea, its really not and its going to make your troubles worse. As long as the gasket on the cap is not hard as a rock or torn, it should seal fine. How much boost are you running? Want to know if excessive crankcase pressure is causing your issue? Gut a PCV valve, install it on the valve cover, then attach a line to your boost gauge to the nipple on the gutted PCV valve (Be sure to plug the end of the PCV hose coming off the intake manifold) and do a pull to 7K in 2nd gear and glance at the gauge. If the gauge registers pressure, youve got your answer and the solution is to upgrade the PCV system.
The idea is to increase the size of the vents on the valve cover and increase the size of the line from the VC to the intake pipe. FWIW, I run dual -8's off the valve cover to a sealed catch can, and a -10 from the can to the intake pipe. This is overkill for my current setup, but I will be going bigger soon. Ive got no PCV valve, my boost gauge is attached to that port with a fitting I installed, and the PCV port on the valve cover has an identical fitting with a cap on it so that I can attach my boost gauge to the valve cover to check pressure as I described above. During a WOT pull, (My turbo is spiking 28 and tapering down to 22psi, its all shes got) with my boost gauge tied to the VC, the gauge tries to go to -1 vac. This is what you want to see as it is indicative of a sufficient PCV system. I never pop the dipstick, and the oil cap never leaks.
 
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