OK, After hours of trying to track this down I wouldn't believe it if I hadn't felt the air leaking out with my own fingers. When I pressurize the system by blocking the intake with a soup can, I have tracked the boost leak to....where the main oil return attaches to the upper oil pan. Stock twins with about 8000 miles on the entire engine including turbos.

A. Is this bad? I mean, I can loosen the two bolts and coat the gasket with FIPG.
B. How does charge air in the boost system get to there? I know the sequential system well and this blows me away. I must be missing something.

 

What exactly are you pressurizing? If you pressurize the entire system like I have seem some people do, it pressurizes the crankcase as well.

Of course this would allow air to leak at the turbo drains. I am not a fan of the whole system boost leak test.

Once the crankcase is in the mix, air will naturally leak from too many places and it becomes impossible to keep track of really.

 

How would you recommend doing a boost leak test without pressurizing the whole engine
?

 

Thanks for the quick reply. I guess that makes sense. So it goes without saying that I have a very minor oil leak. But not necessarily a boost leak?

 

Two replies in 5 min on CL and nothing on supraforums. CL has always been good to me. Thanks guys. Any more info appreciated.

 

Supra forums has been ****ty lately im having boost issues and know one ever answers.

 

I would test from the turbo inlet to the tb and then rely on a vacuum leak test to find leaks beyond the TB personally.

I know alot of peeps pressurize everything and then try to listen through the tailpipe, oil filler etc, but I dont see the point. If you have a vacuum leak, it can be found with more traditional methods, and everything from the turbo outlet to the tb can be tested without having to chase normal losses past the rings, pcv etc.

I dont know, I may be missing something here. This is just my personal, non-turbo guru take on it.

 

Well Supra fourms is saying that your rings are worn.

 

What was the reason for the test? Is the car running okay? If you are concerned with the condition of the rings, get a leakdown tester and go from there. At least with that, you will be restricting the test to within the cylinder, as opposed to the entire turbo system, intake, crankcase etc.

I still say its normal for the crankcase to pressurize doing it the way you are. The rings are going to leak, period. The question is how much, and that can only be accurately determined with a leakdown test.

 

Oh, one thing they said on SF that I agree you should check is the tube going from the passenger side valve cover to the intake piping. It needs to be capped off on both ends, or at least capped off on the intake side. If it is still in place, you are pumping air right into the bottom end.

 

Leakdown test!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

Yea I saw that on SF. My entire engine top to bottom is just over a year old. It is running very strong and I think that the crankcase is getting pressure from the unchecked valve between the twins and the exhaust valve cover. The whole reason I was doing this is because I think I have found my issue with sequential. The 1/8" vaccum pipe that connects the pressure tank with the rest of the twins vacuum loom was clogged. I blew it out with 50 psi from a compressor (don't worry it was disconnected from everything else when I did it) and I felt like doing a boost leak check while I was reconnecting the IACV/EGCV arms would be prudent.

All my piston compression/oil rings are essentially new and the engine is strong. I'm not saying it's not right, I'm just a little doubtful based on the way I built this thing.

So....to delve a little further. Is it possible for pressure in the valve area to get to the bottom end without going through the bore/piston. Maybe an amateur question, but the answer will affect how I feel about this issue.

Thanks for the inputs.

 

Yes. This is what I'm thinking right now. I'm going to re-try the test with this capped and see if I get the same results.

 

If by the valve area you mean the top side of the valves in the valve cover cavity, then yes, air will just flow down through the oil drains into the crankcase. If you mean pressure in the chamber, then no, not really. The rings are pretty much the only out unless of course all valves are open at overlap and it just blows out the exhaust.

If you still had that hose on between the valve cover and turbo side intake when you tested, that is why you were seeing excess pressure in the crankcase. Like I said, that's pretty much a straight shot to the crank.

 

you need to disconnect the crank case hose (passenger side) from the intake system when doing a boost leak down test that way (also the drivers side if you removed the stock pcv for a -an fitting).
when you put boost into the crank case it will usually leak from the seals on the drain line because they aren't meant to be pressurized and if you have a leak here while the engine is running normally its a sign of crank case evacuation problems, and the return line will get backed up and could cause turbo damage.
since you are the cause of this leak by putting pressure in there manually, its nothing to really worry about unless oil is leaking from the fitting while the engine is running.