Boost leak test result question.

[keslerkaiyu]

When I did my boost leak test, air blows out from the hose coming off the valve cover nipple (the one circulating to the intake). I don't remember this happening in past leak test.

Is this supposed to happen?

thanks.

 

[Barracuda]

did you do the BLT before or after the turbo?

In an engine that's 100% perfect, there shouldn't be air coming out at all. Then again, our engines aren't perfect. Though - There shouldn't be coming too much air from that nipple, either.

Possibilities:

Turbo seals
Faulty PCV-valve
Valvestem seals


If you hooked the leak tester after the turbo, you can rule out the turbo seals. If not, do so just to rule that out.

Check the PCV-valve. unscrew the valve and try to lead compressed air through it and see if it leaks. Or you could just plug the hose going in the valve and do a BLT again.

And if both of above are ok, I suspect the valvestem seals... which are pos to change.

 

[the_mork]

It is your PCV. They don't cost much and you can get by in the short term without it working properly but you'll need to replace it. DO NOT get an oem replacement PCV you MUST get an oem Mitsubishi PCV because the other ones are junk. You can order a new one from extremepsi.com.

The easy way to check if a PCV is bad is to take it off and blow into the nipple, if any air goes through at all then it is bad and needs to be replaced. Be careful when you replace it because the valve cover is very easy to crack.

 

[keslerkaiyu]

did you do the BLT before or after the turbo?

In an engine that's 100% perfect, there shouldn't be air coming out at all. Then again, our engines aren't perfect. Though - There shouldn't be coming too much air from that nipple, either.

Possibilities:

Turbo seals
Faulty PCV-valve
Valvestem seals


If you hooked the leak tester after the turbo, you can rule out the turbo seals. If not, do so just to rule that out.

Check the PCV-valve. unscrew the valve and try to lead compressed air through it and see if it leaks. Or you could just plug the hose going in the valve and do a BLT again.

And if both of above are ok, I suspect the valvestem seals... which are pos to change.

The leak is not from the PCV valve. It's from the nipple on the side of the valve cover next to the CAS. I hope that clears up the confusion.

And yes, I did the BLT from the turbo inlet. The reason I did the test is because it's not letting me boost past 10psi.

thanks.

It is your PCV. They don't cost much and you can get by in the short term without it working properly but you'll need to replace it. DO NOT get an oem replacement PCV you MUST get an oem Mitsubishi PCV because the other ones are junk. You can order a new one from extremepsi.com.

The easy way to check if a PCV is bad is to take it off and blow into the nipple, if any air goes through at all then it is bad and needs to be replaced. Be careful when you replace it because the valve cover is very easy to crack.

It's leaking from the nipple going to the Snorkel intake. Not the one going to the BOV. So I don't think the PCV valve has anything to do with it, right?

Sorry, my first post was confusing.

 

[the_mork]

Your post was clear enough. It is the pcv. The pcv is allowing pressure to enter where it shouldn't and the breather is the easy outlet, replace the pcv and it will stop.

 

[habitatguy187]

There is a hose that runs from your intake manifold into your pcv valve, which sits on the top left corner of your valve cover. That valve is only supposed to let air flow from the valve cover to the intake manifold (when the car is under vacuum) and close when the car is under boost, not allowing fresh boost into and consequently out of the valve cover through the breather tube.

If the pcv valve is bad, which happens often, then it will allow this to happen. Like already said take out the pcv valve and blow into it in the direction that you would blow into the valve cover, if you can blow air through it, then it's bad.

 

[keslerkaiyu]

thank you.

 

[Calan]

It may not be the PCV valve. Air can also leak past your valves and rings and into the CC, especially if the engine is cold. You should have the motor warm when doing a BLT, and it doesn't hurt to put it at TDC to make sure all the valves are closed also.

I'm running a brand new PCV valve and a check valve between the IM and VC, and I still have some leakage at the VC nipple. (in fact, it's the only leakage I can find).

 

[habitatguy187]

I'm running a brand new PCV valve and a check valve between the IM and VC, and I still have some leakage at the VC nipple. (in fact, it's the only leakage I can find).

I feel ya


Kept blowing oil cap gaskets so I made a second breather nipple, temporary fix but it's much better than cleaning oil out of my spark plug resevoir all the time..

 

[keslerkaiyu]

It may not be the PCV valve. Air can also leak past your valves and rings and into the CC, especially if the engine is cold. You should have the motor warm when doing a BLT, and it doesn't hurt to put it at TDC to make sure all the valves are closed also.

I'm running a brand new PCV valve and a check valve between the IM and VC, and I still have some leakage at the VC nipple. (in fact, it's the only leakage I can find).

You are corrrect... I just did my BLT in the morning and never started my car...

I will try a warm engine and see what happen. The engine is newly rebuilt by Showdown motorsport in Ohio. It was a rebuild long block, so I don't think it's the valve. At least I hope it's not.