boost leak question

[bluetlr2001]

Ok so my problem is i was doing a boost leak on my car and the only leak i could find was oming from the valve cover. I thought it was the pcv valve so i blocked it off and it still had air leaking out. Im not sure were it could be leaking from unless its my valves or rings. Oh yea the motor has 136,000 miles on it. Could it just be wear on the motor or what? Ive tried searching and didnt really find much except everybody that had similar problems it seemed it was there pcv valve.

 

[oldman]

Are you testing from the turbo inlet? If so, move the tester to the TB elbow and retest. Some air will get past the turbo seal during a STATIC pressure test.

 

[bluetlr2001]

I have been testing from the turbo inlet. And ive also tested from the tb elbow but i cat remember if it leaked out the valve cover then but ill give it a try tomorrow to see if it does still leak. Thanks Oldman youve helped me many times

 

[The_EE]

if its leaking out of the valve cover that means that the PCV Valve isnt doing its job. At least thats one thing that isnt doing its job.

 

[oldman]

I have been testing from the turbo inlet. And ive also tested from the tb elbow but i cat remember if it leaked out the valve cover then but ill give it a try tomorrow to see if it does still leak. Thanks Oldman youve helped me many times

You're welcome. If leaking persists testing from TB while PCV is disabled, the only possible leakage would be intake valve seals or excessive blow by from rings so you might as well go ahead and perform a compression test. Keep in mind that you will always lose some air through the rings, common sense as well as compression test results will help determine what is acceptable.

 

[bluetlr2001]

I tested it a the TB again and it doesnt leak hardly at all. But you can hear it coming through the exhaust. But im gonna do a compression test today. I guess its probally just normal wear.

 

[oldman]

I tested it a the TB again and it doesnt leak hardly at all. But you can hear it coming from through the exhaust. But im gonna do a compression test today.

That is good, this means it was only the turbo seal allowing air to enter the crankcase via the oil return line, normal during a static pressure test due to lack of oil pressure as long as the turbo doen't have excessive shaft play and isn't smoking during normal operations.

As for air out of exhaust, there are only several possibilities.

1. Stuck open EGR.

2. Valve overlap (during end of exhaust stroke and beginning of intake stroke where both intake and exhaust valves are open), meaning one of your cylinders is at or near TDC, bringing #1 cylinder to approximately 30* after TDC will avoid valve overlap.

3. Bent or unseated valves, which will be apparent with a compression test.

 

[bluetlr2001]

Well i didnt get to do a compression test today. But as for you talking about the egr. Ive changed it out for another used 1 I had on an old motor. But the reason i changed it out is because i was doing a boost leak test and i plugged the vacuum lines coming off the TB and when i did the line coming from the EGR valve had air leaking out of it but when i changed it the 1 I put on it done the same so would that mean its stuck open?

 

[oldman]

Well i didnt get to do a compression test today. But as for you talking about the egr. Ive changed it out for another used 1 I had on an old motor. But the reason i changed it out is because i was doing a boost leak test and i plugged the vacuum lines coming off the TB and when i did the line coming from the EGR valve had air leaking out of it but when i changed it the 1 I put on it done the same so would that mean its stuck open?

A stuck open EGR valve leaks air from intake to exhaust manifold, hence air out of your exhaust, an internal leak if you will. What you're describing sounds more like an external leak, either the gasket or vacuum lines.

 

[bluetlr2001]

Well were the EGR was leaking was boost coming from the head and it was leaking out of the vacuum ports on it. Im not sure if thats normal or not. But it was loosing air out of were you hook the vacuum lines to the EGR valve.

 

[oldman]

You're in Tennessee, why not just block off the EGR and remove some of the unnecessary vacuum hoses?

 

[bluetlr2001]

Sorry for bringing this thread back up but i finally got my egr blocked off and i done a compresssion test and here are the numbers

145 140 155 160

Now i have no boost leaks but im hitting fuel cut at anything past 12psi. Anybody have any idea what could be causing it to do that

 

[romeen]

Sorry for bringing this thread back up but i finally got my egr blocked off and i done a compresssion test and here are the numbers

145 140 155 160

Now i have no boost leaks but im hitting fuel cut at anything past 12psi. Anybody have any idea what could be causing it to do that

Although your compression numbers are above the service limit, the variation between cylinders 1 and 3 is borderline. Maybe this does suggest a problem with the valve seats as previously stated. I don't know that this would have anything to do with the fuel cut though. Did you do the wet test?

 

[bluetlr2001]

Nope i didnt do the wet test i didnt know about it til just a little while ago. so now ive got to wait til monday to test again because i left my tester at work, which suxs

 

[romeen]

Also have you had any of the usual symptoms of a head gasket failure?

 

[bluetlr2001]

Nope it doesnt smoke or use oil or water so im pretty sure its not a blown head gasket. Havent ever had it over heat either. It just likes fuel cut rite now.

 

[oldman]

1. Is your BOV vented?

2. Is you DSBC hooked up to the BOV line?

3. What are your adjustments on the SAFR?

4. What is your mas reading when you hit fuel cut?

 

[bluetlr2001]

My bov is recurculated now, And for my boost controller i have it tapped into my intercooler pipe rite before my bov. And ive got the afc set on 0 right now, and im not sure what my mas air is reading, but my short fuel trim stays normal and the long fuel trim goes to -2 anytime the motor gets a load on it, but at idle my fule trims are both at 0 and stay there when you free rev it

 

[oldman]

Sorry, I looked at romeen's profile instead.