boost fluctuations @ WOT, now can't get any boost

[bondie]

hello,

Long time reader, first time posting.
I have a 93 eagle talon tsi. the car is stock, except for a cold air intake, an aftermarket boost guage and an intercooler(not sure if it is standard or not).

the car has been sitting the last two years until i've had the time and money this past summer to work on it (needed to replace intake valves, rocker arms etc.) I got it fixed and the car has been running good the last 3 weeks except for a couple leaky gaskets on the coolant thermostat and the oil return from the turbo.

two days ago I was driving home at night (i mention night because the aftermarket boost gauge isn't backlit so I couldn't see the boost pressure) and when accelerating hard, instead of a steady whine I would usually hear from the turbo, it would fluctuate in pitch and loudness at a rate of about 1-2 time each second. ( only way I can think to describe it: instead of ZZZZZ etc. it sounded like ZZzzzZZzzzZZzzz etc. ) the next day I noticed that the car wouldn't boost positive regardless of how hard I accelerated, instead only reaching 0. Also, when idling and driving at a constant speed the boost level is much lower than it used to be.

What i've been able to determine: the internal turbines (right word?) on the turbo itself still rotate freely. the wastegate actuator still functions correctly.

note* when looking over the turbo this afternoon I found that I had some severe cracks around the two valve cover bolts inbetween the camshafts and closest to the timing belt side of the engine. This is allowing oil to spray into the engine compartment every time I drive it. i'm pretty sure this problem started at the same time that I lost my boost. might this be the cause of my boost problem?

Thanks for reading, I hope someone can help me out!

 

[boostinRWD]

Edit::bad grammer I guess.

The cracks are deffinately the issue. What caused them is what needs to be determined.
Fluctuating boost condition leads me to believe the wastegate houseing has cracks,,it may function but not correctly.

 

[bondie]

yes that is correct, I don't have a wideband on the car. And yeah, I started writing this thread and in looking through the forums as i wrote it I saw that a lot of times problems come from the actuator, however in going out to check it ( it works correctly) I noticed the cracks on the valve cover. Is these cracks what are preventing me from being able to build up boost pressure? (does that area of the engine become pressurized, so it would be leaking out there?)

edit:

the turbo has an internal wastegate

 

[boostinRWD]

Yes it is an internal wastegate. It still has the housing, some call it the o2 housing.

 

[bondie]

ok i see! I did a quick visual examination of the waste gate housing and used a stethoscope to check for air leaks. Didn't find see or hear anything unusual, but do i need to have the car reving, or is it acceptable to check for leaks while it's idling?

Also, I used some JB weld to fill in the cracks on the valve cover. I meant for this to be a temporary fix while getting a new valve cover. I probably should have checked if that would be ok on here first. In hindsight, would JB weld be an acceptable quick fix until I can get a new valve cover?

 

[eligst21]

Just idling or revving, won't help you find a boost leak. You need to pressurize the system. I reccomend doing a boost leak test and let us know the results. To me sounds like a boost leak somewhere. I would say the we is fine, but you can blow air into the nipple and see if the arm moves. That would let you know whether it is even opening. What turbo is on it? I'm assuming the stock 14b. But for a icar sitting for so long, I would say there is bound to be a hard rubber line that has since cracked, causing a boost leak. Do a boost leak test.

 

[bondie]

Yes it has a 14b turbo. Thanks guys, I'll check the system for leaks this weekend! Also, I read a thread in the forums about how to conduct the boost test, as far as checking for the actual leaky hose, soapy water sprayed on will be ok for finding leaks, correct? I'll post the results as soon as I find out. Thanks!