air through breather hose

[vinnio]

Okay I’ve tried searching but couldn’t find a definite answer.

I’m helping a friend work on her 96 GST. I was doing a boost leak test when I discovered a lot of air pushing through the breather hose. The one that’s going from the valve cover to the intake pipe. Is this normal? We went out and bought a new pcv valve but haven’t had the chance to replace it yet. Her old one wasn’t very bad though... I could barely blow through it, but either way I could get air through the wrong way. It also has a rattle, so I don’t think it can be that bad.

Okay here’s the kicker! When I put my hand over the breather hose, it leaks from somewhere else. The front side of the engine! If I were to guess, right below the exhaust cam. I don’t know what this could mean. It won’t even hold 10lbs of air for 5 seconds so I know something is up. Also just fyi compression is about 160 across the board. What do you all think??

Thanks a lot! I really want to be able to help her!

 

[eagle_talon90]

Did you make sure when doing the boost leak test that you put the engine to ~30* past TDC? This makes sure that at least one set of valves is closed in each cylinder so the air isn't just leaking straight past the cylinder and out the exhaust. Just a thought...

 

[vinnio]

Ill give it a shot. I knew you had to set the cam timing before a boost leak test, I just didn't know how necessary it was.

Where do you think it could be leaking from on the front side of the engine? Head gasket?

 

[xdxoxuxgx]

If it was a bad head gasket you would be leaking more than just air.

 

[vinnio]

yea for sure. Plus the compression test was fine (160 ish across all 4) It seemed lower than the valve cover gasket too... what else could leak air down there??

 

[Colt4G63 also]

yea for sure. Plus the compression test was fine (160 ish across all 4) It seemed lower than the valve cover gasket too... what else could leak air down there??

J-pipe gasket? It isn't one of those glued together chinese Evo 3 GT turbos is it? If so, it's probably coming out of the side of the compressor housing . Do you have access to soapy water?

 

[vinnio]

Nope, this thing is actually 100 percent stock! It's not on the cold side of the turbo. To my surprise, its coming from the lower timing belt area. If I were to guess, somewhere lower than the exhaust cam sprocket.

I just put a new pcv valve in along with new spark plugs (old ones were worn out autolite plugs). The thing runs a lot better! But it's still not holding pressure while doing a boost leak test. I told her to keep driving it and see if the problem happens again. I put like ten miles on during a test drive and it seemed fine...

I still would like to figure out what's leaking down there tho!! It's really bugging me.

Thanks

(EDIT: I read my posts, and by front side of the engine I mean timing belt side. Sorry I wasnt clear.)

 

[Colt4G63 also]

EGR valve, vaccum hoses?

 

[jrohner]

It's most likely the PCV valve, they almost always leak. If not it is probably some other emissions crap leaking.