HELP... I need some unconventional boost leak wisdom here!

[90gst_sean]

I have had a super boot leak! I mean, one that will take a 2gal mini compressor in 1 min with out moving the boost gauge.

I rebuilt the lower end a month ago; 6 bolt w/ 2G pistons. Compression is 178 to 185 across the board.

I WAS leaking at the injector seals, but that can't be the only problem.

The car runs OK. I still need to tune for the 2G pistons and this leak must factor in there some were.

I can hear the air moving through the intake manifold to the cylinder head, but I just had the head in the machine shop less than 15,000 miles ago; new seals and a couple valves.

If I'm just retarded and this is as simple a rotating the block and aligning the valves, PLEASE clue me in!! I'm pretty sure I've tried EVERYTHING.

Also, when I had the block bored; I had the head in to be pressure checked at the same shop do to a broken ex. stud I buggered up. Although I'm really not confident that the check was done. I wasn't charged for it.

 

[90gst_sean]

Am I correct in assuming that my valves are OK and not the problem do to having good compression numbers?

Would the car being cold have any affect?

 

[steve]

Did you make sure to check that the engine isn't stopped with one cylinder in overlap?

Steve

 

[90gst_sean]

I under stand thing is cut and dry for most of you but not me, this has been a problem I cant pin point and I have no problems working on cars normally. Point being, I must be over looking something simple. Your experience would go a long way to help.

There seems to be pressure in the valve cover. I can feel it when I take the oil cap off.

If this is the case there aren't to many ways air can get in there. Its got to be blowing by the valve stem seals..??? Is this correct?

What should I look for it I take the valve cover off? I would like to get some feel back before doing that though... Any feed back... please

I'm going to have to bag it for the night soon, so someone please respond.

 

[90gst_sean]

Steve- I bumped the key to move everything a bit, and no change. I've tried to tackle this I think four different times now and i get the same result

Isn't that the definition of a "moron"

 

[donmagicjuan]

It could also be your turbo's oil seals or the PCV valve. If you haven't done so already, try repositioning your tester at a point closer to the throttle body. That cuts out a good chunk of the system, which is helpful when trying to narrow the problem down. If you get good (or at least better) results there, start working your way back to the turbo until you uncover the massive leak. On the other hand, if the leak is still present when testing at the TB, you've at least isolated it to a handful of possible locations.

As an FYI, you can rule out the valve overlap issue by rotating the crank to about 30 degrees ATDC on #1, but if you've tried several different positions it's likely not the problem.

I hope that helps.

 

[oldman]

There seems to be pressure in the valve cover. I can feel it when I take the oil cap off. If this is the case there aren't to many ways air can get in there. Its got to be blowing by the valve stem seals..??? Is this correct?

1. As you suspected, valve seals. However, many fail to realize worn valve guides can not be fixed with new valve seals and do not replace them during rebuild.

2. Piston rings, you can rule this out as long as compression numbers you listed still stand.

3. PCV valve.

4. Turbo CHRA, this could be normal during a static pressure test as long as there are no obvious signs of a failing turbo such as excessive shaftplay.

What should I look for it I take the valve cover off? I would like to get some feel back before doing that though... Any feed back... please

Process of elimination,

1. First you move the leak tester down stream (like the TB elbow) to eliminate turbo.

2. Disable PCV to eliminate ........ PCV.

3. Repeat compression test to eliminate rings.

4. Remove intake/exhaust manifold and check both intake and exhaust ports for signs of oil leakage. You can also open the VC during a leak test, pour oil over the valves, if it's leaking that badly you will be able to see something.

Other things to consider.

1. Disable your mbc.

2. Listen for leaks at the tailpipe.

Good luck.


edit: beaten by don

 

[90gst_sean]

Sorry, I tend to be a little inpatient. Thank you!

Now, I have some work to do...

 

[oldman]

Sorry, I tend to be a little inpatient.

Yes, bumping is not allowed.

 

[90gst_sean]

Now we're getting some were!!!!

I'm 90% sure the massive leak was a 15,000mile old PCV valve; go figure. They only go in one way so I know its not back wards . Is there a better means of venting crank case pressure other that the OEM PCV?

The system looks like it will hold 7psi with out dropping noticeably. Thats 100% improvement from before. I think I felt air at the blow off; but thats nothing compared to the frustrations I've dealt with over a PCV valve.

I'll let you know how it goes once I have more time to seal it up good. I want to get out there and see how fast this thing spools with true boost.

THANK YOU!!!!

 

[oldman]

I'll let you know how it goes once I have more time to seal it up good.

Seal what up? The solution here is an OEM replcement PCV. Glad you found the "big leak" but it shouldn't stop you from completing the leak test, 7psi is no where near perfect.

 

[90gst_sean]

No, I'm sure 7 psi is no were near perfect. I'm just running out of wrenching time and still have to get to the parts store.

I meant seal it up, as the rest of the intake track. I should be able to take it on again tomorrow morning.

A good holding track should be able to handle what ever amount of boost you run through with out dropping steadily on the gauge; correct? Should I be looking at the gauge on the compressor or the boost in car? There seemed a five pound difference, but this could have been the time it took to move spots.

I'm a one man pit crew...