Will a loose oil cap cause boost leak?

[DSMnOOb00]

Question; will a loose oil cap cause a boost leak?

I found some oil on my valve cover and it seems to be coming from the oil cap.

 

[92AWDHX40]

Never heard of that sounds like you have a bad oil cap.

 

[jtmcinder]

Well, if you have a leak between the intake path and the crankcase, such as a leaky intake valve seal, then I suppose the oil-filler cap could be the second half of a boost leak, but it's much more likely to be blow-by-related, instead.

 

[DSMnOOb00]

Yeah, I already ordered one from extremepsi, but I was woundering if it maybe cause a boost leak too?

Isn't the valve cover under pressure?

 

[LiquidX]

Your crank case should be under a vacuum or atmosphere pressure. Boost pressure build up is bad and is generally caused from a a PCV. If you have oil on your VC it's more than likely a bad oil cap gasket and the other possibility is a cracked valve cover if the bolts are tightened too much.

 

[PotatoFlakeSTi]

If there is a leak from your oil-cap area, the problem is probably blow-by... So just a symptom of another problem.

 

[DSMnOOb00]

well its not much oil, I just had the car rebuilt top/bottom OEM spec

 

[knochgoon24]

If the seal is bad, even just a slight amount of crank case pressure will push oil out into the spark plug area.

 

[NOSLO2PT0]

Get a new rubber gasket for the oil cap from the dealer. The original one is probably hard as plastic by now.

 

[preludeachris]

Get a new rubber gasket for the oil cap from the dealer. The original one is probably hard as plastic by now.

its hard to get parts from a dealer when your car is more than 10 years old ..

 

[NOSLO2PT0]

They can still order it. Just means they won't have it in stock. Do you think that after 10yrs, they just stop having parts available? How do you think all the 1G's stay on the road? Really now.....

 

[bryanwheat]

its hard to get parts from a dealer when your car is more than 10 years old ..

Not at all, you go in there, they look it up and they order it. Pretty simple.

 

[92AWDHX40]

Well with a 1g its not that simple some parts arent avaialable any more, i used to work at mitsu dealer in college, even now some parts are obsolete.

 

[DroopYeyeS]

I have this same oil cap leak issue. Just put a new cap on yesterday. Only boosting a mild 10psi, but getting puddles of oil in the spark plug area. I'm also fairly sure I have a boost leak. As the RPM's come up I have to use less throttle or it hits cut (almost like a rev limiter) at different RPM's.

 

[V8Killer25]

all you have to do is a boost leak test... anywhere you hear a loud hissing sound is the source of your leak and should get it fixed asap!!!!

 

[DroopYeyeS]

Thanks Killer. I know the process, just got the car running again last night, so I've not had a chance to do that as of yet. More interested in the oil loss at the cap. will be checking the PCV tonight.

 

[Funfettie]

If you have a boost leak from your oil cap, than boost is entering the engine somewhere that it shouldnt. Valve seals or guides, piston rings, head gasket. The pcv valve is a common one too. Id pull the valve cover off keeping the pcv valve plugged in, and try the boost leak test again. listen really close and feel for air leaking. if you have to, use soapy water to help find the problem spot