i decided to check for a boost leak today since i wasent boosting high like im saposed to and i found out air is coming out from around the oil cap? is this normal i was told to check my compression and i got 135 on all cylinders so im good with that but what would you sugjest doing. could this be a turbo seal or something or maybe just get a new cap. is it normal to have air in that area?

 

If the rubber nitrite seal is hard and there is no flex in it, just change the seal if you can get a new seal from Mitsu. If not, change the cap. A low budget fix is to get some flat rubber (innertube-like material), trace the outline of the original seal, cut to shape and install. As long as it is as thick as the original, then you shouldn't have leaks up there

 

ok so there is saposed to have pressure there ok good yea because if i put my hand on it and lightly push it wont leak anymore ok so this is normal for a cap correct?

 

yes. You will have pressure in the head from the pressure from the crankcase. remember, all engines are pressure generating machines, unless you're in space or in a vacuum Anyway, the test you performed did indicate a weakness in the seal of the oil cap, so either replace the rubber seal or the whole thing if you aren't keen on making a seal yourself.

If the seal you have is still good, check the cap lock fingers underneath the cap. Those fingers working in conjunction with the seal is what "pulls" the cap down in place. It is the anodized finger that is held in place by an 8mm nut and can be adjusted from the phillips head bolt at the top of the cap. You can remove it and then flex it back down to straighten it a bit to "increase" the length of the fingers. If this doesn't solve the problem of leaking oil under pressure, then it is definitely the seal.

Go to a parts store like NAPA, walk in with your oil cap and ask for a replacement seal. It doesn't have to be Mitsu EVO specific, as long as it fits and is pliable, you will be good to go. It shouldn't be very expensive at all.

 

did you cap off the pcv valves?

 

yea ill prob end up buying a new cap my oem cap when i tried to remove the finger as u said it wont let me remove it it tends to spin with everything and wont tighten ether and im holding it with a hex skrew driver and size 8 mm wrench and trying to turn it ill go check out napa today and ill let u kno thanks alot

 

So, it sounds like it's the finger assembly that is jacked. In this case, make sure the replacement cap you find at NAPA fits. Another alternative is to find one in a scrap yard from a Lancer. If there's no indication of oil leak from the oil cap, then you're good to go as long as the cap fits your 4G63.

 

yup i think im going to save myself the hassel lol i just orderd the part from the stealership and its 17.96 funny thing is the one by my house is asking 22? wtf lol and there delay from my part getting to them is next mid week and for 17bucks i can get it friday from this other dealership lol ... hope this fixes the big boost leak i have so i can go back to boosting 29.5 ill let u kno how it goes friday

 

ok bad bad bad, so i fixed my first problem it was because i had my home made oil catch can hooked up to the pcv valve and then to the intake pipe and when pressurized it would put pressure in the crankcase. sooo i disconected it and just put a breather it tended to fix the problem but i noticed when i pressurized to 28psi or 30 high pressure anyways it would put air in the crankcase making it leak out the pcv valve if i pluged the valve it would come out the oil cap... so now im stuck wondering if something is wrong and my compression on each cylinder was 135 sooo any ideas?

 

bump

 

bump

 

Went to english racing got everything checked out and everything is in perfect working order and i guess its normal they said to get some air in the valve cover so im happy it was nothing seriouse thanks guys

 

Cool! It doesn't matter what engine, for there'll always be some fluid pressure in the cylinder head if it exists here on earth. Since you are boosting big, I do recommend to reinforce those areas like the PCV going to the intake manifold. What I mean is to look into installing an -AN fitting with steel-braid hose with catch can in between the cylinder head and intake manifold. On the exhaust side port going to the intake pipe, you can do something similar, but it may be overkill. Some people do this. Just suggesting. If anybody has a better solution, please review what i wrote.

 

The leakdown test on a brand new racing engine is supposed to be around 6%. What that means is some air will leak by the piston rings on a perfect engine. The more pressure you apply the more the leak. This air goes to the crankcase and will exit any possible place like a filler cap with a bad gasket.

Just supply a good place for the air to exit. Pressurizing the crankcase provides no usable
information.

 

good read a lot of smart a$$ comments from people who don't know jack

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