boost leak test results...bad?

[dan2288]

Ok, so I just finished doin a boost leak test. I got it to 20 psi but i heard a big leak and it went down to 0 psi in a couple seconds. I found that the air was goin thru the pcv valve, in the valve cover, and out the valve cover breather nipple. Is that normal or is something wrong? Also when i started my car it was burning oil. Is that normal? It went away I think

 

[rEclipserGST]

Try replacing the PCV and see how high you get it. But as far as I know, the pcv goes out alot. Did you leak around 8, 10, 12, and 16 psi? It shouldnt really matter unless your actually boosting to 2 psi anyway. Im not 100% though, correct me if Im wrong.

 

[pboglio]

It could be you didn't rotate the crank into position to seal off the intake/exhaust valves.
Without doing that your pretty much counting on luck for the boost leak test.

 

[dan2288]

yea, it started leaking right away. Isnt the pcv valve a one way only valve? Air shouldnt be coming in the valve cover thru it. Am I correct?

 

[pboglio]

Pull the PCV hose off the PCV and put a bolt in it to seal it. Then retry.

 

[dan2288]

Ill have to retry it tomm then. Ill just get a new pcv valve anyways since theyre so cheap.

 

[chico904]

Ill have to retry it tomm then. Ill just get a new pcv valve anyways since theyre so cheap.

Make sure to only get a genuine Mitsubishi pcv valve, as most others leak from the box. Also put in the USP check valve Check Valves - US Plastic Corporation after the PCV valve. After that, you will not leak back into the valve cover.

 

[GRAVEDIGGER]

Make sure to only get a genuine Mitsubishi pcv valve, as most others leak from the box. Also put in the USP check valve Check Valves - US Plastic Corporation after the PCV valve. After that, you will not leak back into the valve cover.

+1 to the US Plasics valve. Very cheap and very reliable. They will hold up to 150psi without leaking.

 

[dan2288]

Make sure to only get a genuine Mitsubishi pcv valve, as most others leak from the box. Also put in the USP check valve Check Valves - US Plastic Corporation after the PCV valve. After that, you will not leak back into the valve cover.

hmm anyone have a diagram of this?

 

[GRAVEDIGGER]

The following link should explain it.


http://www.dsmtuners.com/forums/newbie-forum/229338-stupid-pcv-question.html?highlight=STUPID+PCV

Take a look at the drawing near the bottom of page 2.

 

[chico904]

hmm anyone have a diagram of this?

It goes valve cover > PCV valve > USP check valve > Intake manifold. All you are doing is adding the check valve between the PCV valve and intake manifold. There will be an arrow on the chack valve, make sure it points toward the intake manifold.

 

[dan2288]

cool, where can I get one of these valves at?

 

[chico904]

Check Valves - US Plastic Corporation

 

[dan2288]

Ok, so if I get one of those check valves and reuse my bad pcv valve, It would still work fine?

 

[GRAVEDIGGER]

Yup, it sure will.

Just make sure that your old/bad one is clear of any debris that might plug it. Just rinse it out good with some brake cleaner or something. The only reason you even need to keep it in the equation (since the new us plastics valve will be doing its job of keeping boost from pressurizing the crankcase) is because it has a specific size orifice which you need to keep in the system.

 

[dan2288]

okk, sounds good. I just ordered 2 of the check valves

 

[GRAVEDIGGER]

Good deal. I think this is a common thing that is overlooked. Alot of people never give two shits about the pcv system, but it's actually very important. These valves work great. You won't be disappointed.

 

[kp116]

It could be you didn't rotate the crank into position to seal off the intake/exhaust valves.
Without doing that your pretty much counting on luck for the boost leak test.

I don't think there is any position of the crank so that all intake and exhaust valves are closed.... So making them all seal would be impossible...

 

[TofastForU_99]

true ^^^^

 

[pboglio]

I don't think there is any position of the crank so that all intake and exhaust valves are closed.... So making them all seal would be impossible...

WhatWTF Demonstrate exactly how you can do a boost leak check on the entire intake system when your leaking pressure thru the intake or exhaust valves? It's not possible. You have to turn the crank over by hand to seal up the intake and exhaust valves. There is approximately a 5* window where everything is buttoned up. The pressure alone is enough to kick the crank over, I have to sit there and hold the crank in the exact position with a ratchet.

Trust me on this one, I can run 40 psi of pressure and every bit of it will leak thru the motor without doing what I just stated. And when you have 40 psi in the intake, it is a piercing sound which requires earplugs, so you hear the most minute leak.

 

[boostforfun]

How do you get much air in the intake unless you open the throttle body blade to let it in?

 

[pboglio]

Don't need to touch the throttle plate, it's bypassing the throttle plate presumeably thru the bleed screw.

 

[jesse_shift51]

Great thread. I had the same issue and assumed it was the rings at first because I had just replaced the PCV. This caused an immense amount of frustration because I had just rebuilt the motor. Finally came to the conclusion, via research, that the PCV was the cause of the leak and used the suggested check valve, thanks chico. Works great now and I found the real leak. Thanks for the knowledge.

 

[JFZERO ECLIPSE]

My brand new oem pcv valve leaks as well what size should I get to solve this problem..I notice there are quite a few different sizes to choose from and Id hate to guess it...

 

[chico904]

My brand new oem pcv valve leaks as well what size should I get to solve this problem..I notice there are quite a few different sizes to choose from and Id hate to guess it...

You do not need to get a new one, you just want the PCV valve for its "snorkel-like" end design. All you need to do is install the check valve directly after the PCV valve in line with the intake manifold. After this, you do not need to have a functioning PCV valve. You want the 3/8" linked here.
Check Valves - US Plastic Corporation