H Guys,

Just trying todo a boost leak test, but at about 1bar the 'boost is leaking in the engine' lol... and my little compressor wont push psat 1bar

does anyone know what degrees i need to be at so all the valves are closed?

How can I tell without taking the cam cover off?

Cheers
D.

 

ended taking of the throttle body hose, and plugging up the BOV line...

2bar tested

busted my throttle body hose putting it back on thou.... oops too tight :|

 

i made a little rubber coupler that goes right on the turbo with a end cap/valve stem on the other side. pvc primed and glued everything and use the stock clamp to secure it. holds 30+ psi, but pressure still bleeds from the boost control silenoid...unless you plug it

 

yeah thats how I used todo it, but after hearing that the turbo seals leak I thought I would bypass the turbo...

 

So you ran the test post turbo? So from the inlet of the UICP? Actually due to location, that is easier than removing a bunch of stuff to plug into the turbo inlet.....

 

since I have stock IC piping I just disconnected the expander joint in the UICP and started from there...

 

have you got the results from the test?

 

yeah I got upto 2bar and it held ok..

i am still interested in doing a full test, so if anyone knows how far past TDC all the valves will be closed please let me know

 

Lets see, firing order is 1-3-4-2 so that means at TDC:
Cylinder 1 is about to combust (intake valve closed)
Cylinder 2 is about to exhaust (intake valve closed)
Cylinder 3 is about to compress (intake valve about to close)
Cylinder 4 is about to intake (intake valve about to open)

It's hard to say what degree exactly since you have to know the exact cam opening/closing degrees, take in consideration the valve clearance, etc. But by knowing the sequence above, it should be a few degrees after top dead center right when cylinder #3 intake valve is closed. If you go too far ATDC cylinder #4 intake valve will open.

Place the engine in TDC (be sure it's TDC cylinder #1 and not #4 ), apply the compressed air into the intake and rotate the crank clockwise until the leak stops.

 

Actually it shouldn't matter, it can be ATDC for any cylinder

But know that I think of it, I wasn't thinking about overlap which occurs between the end of the exhaust stoke and the begining of the intake stroke. This maybe a little harder than the easy thinking above

Easy way, just keep rotating the crank until the leak stop

 

yeah i tried trial and error but that didn't work too well

i will start at TDC and go forwards from there..

 

When #1 is at TDC #4 should be in the middle of overlap. If you keep rotating the crank clockwise overlap will end and #4 intake valve will open further but at the same time the #4 exhaust valve will fully close. So as long as your cylinder isn't leaking, you should still have a good seal even with the intake open. So this means it should still be some degees ATDC when #4 overlap ends

 

yeah ok - thats all that matters - exhaust valves being closed

so you think slightly after #1 is at TDC? so start just before and work forwards..

#1 being closest to timing chain yeh?

 

Yeah, slightly after #1 TDC when the #4 exhaust valve closes all the way.

Yes, #1 is timing chain side

 

We have the same issues on our race evo with our race cams. I just take the cams out and be on with the test.