boost leak out of cam seals?

[Hitmachine101]

just did a boost leak test and sure as heck i get above 7 psi and i start having air come seeping out of the cams seals, at least thats what i think its coming out of

anything else it could be coming out of in that general area? besides the valve cover gasket because its not that

anyone else have to replace these things because there not holding boost pressure? because there not leaking oil to my knowledge, everything is dry in the timing belt area surprisingly enough the rest of my motor is caked in oil but not there

 

[bjmauck]

Spray soapy water and look for bubbles to make sure where you leak is.

 

[scottyhops]

did you make sure while doing the boost leak test that your intake valves are closed? it sounds like the intake valves are open and pressure going past the valve seals?

 

[CrawlinZX14]

I would do a compression and leak down test. What is your reason for the BLT? Poor performance? Upgrades?

 

[bryanwheat]

You are probably leaking pressure past the pcv valve into the crank case.

did you make sure while doing the boost leak test that your intake valves are closed? it sounds like the intake valves are open and pressure going past the valve seals?

There will always be intake valves open no matter where you turn the engine. Even if the valves are close the pressure is still against the valve seals.

 

[keltalon]

You are probably leaking pressure past the pcv valve into the crank case.



There will always be intake valves open no matter where you turn the engine. Even if the valves are close the pressure is still against the valve seals.

I agree 100% with this post^^^^^well stated

 

[turbojoeg]

+1 on that last post also.

Soapy water on all couplers, injector seals, intake mani gasket, throttle body ect ect.

 

[92AWDHX40]

Couplers, vacuum lines, brake booster, egr, youll be surprised i found plenty after my fmic install.

 

[turbojoeg]

Make sure you soak the throttle body. The Idle set screw leaks on 98% of them. Also the shaft seals usually leak too.

 

[scottyhops]

You are probably leaking pressure past the pcv valve into the crank case.



There will always be intake valves open no matter where you turn the engine. Even if the valves are close the pressure is still against the valve seals.

i could have sworn i read that timing mark had to be 30 degrees before dead center for all the intake valves to be closed?

 

[eagle93tsi]

This post
http://www.dsmtuners.com/forums/art...st-how-boostpro-net-tester.html#post152554139
has a good diagram on the valve timing. This post recommends 40 deg BTDC to have all intakes closed.

When all of the intakes are closed some pressure will make it up between valve stem and the valve guides and press on the valve seals. I the seals are worn they will leak air and make it into the crankcase.

If the intake valves are not fully closed then there is another leakage path into the crankcase by the rings.

The PCV valve is another source of leak into the crankcase.

This should summarize all of the points where leaks into the crankcase can happen when boost leak testing from the Throttle body.

For the leaks not into the crankcase you should be able to identify most them with lots of soapy water.

 

[Hitmachine101]

did you make sure while doing the boost leak test that your intake valves are closed? it sounds like the intake valves are open and pressure going past the valve seals?

didnt make sure the car was top dead center, knew i was forgeting something

You are probably leaking pressure past the pcv valve into the crank case.



There will always be intake valves open no matter where you turn the engine. Even if the valves are close the pressure is still against the valve seals.

the pcv has a check valve in the rubber piping going to the intake mani, i got sick of blowby and i installed a 100 psi check valve to stop it

This post
http://www.dsmtuners.com/forums/art...st-how-boostpro-net-tester.html#post152554139
has a good diagram on the valve timing. This post recommends 40 deg BTDC to have all intakes closed.

When all of the intakes are closed some pressure will make it up between valve stem and the valve guides and press on the valve seals. I the seals are worn they will leak air and make it into the crankcase.

If the intake valves are not fully closed then there is another leakage path into the crankcase by the rings.

The PCV valve is another source of leak into the crankcase.

This should summarize all of the points where leaks into the crankcase can happen when boost leak testing from the Throttle body.

For the leaks not into the crankcase you should be able to identify most them with lots of soapy water.

thank you for the link that was helpful for sure, ill test again tomorrow with the intake valves closed to see whats up

I would do a compression and leak down test. What is your reason for the BLT? Poor performance? Upgrades?

ive gotten in the habbit of doing a BLT about once every two months

just a good idea in my opinion because couplers tend to back off and loosen up on me in the past, and id rather not be blowing boost out of somewhere messing up my A/O ratios dont need more carbon on my rear bumper

and ya noticed over the past week my 14b at 10psi isnt pulling as hard, figured it was a good time to check with these dsm s you never know right

thanks for all the input guys ill check in tomorrow with my results

 

[keltalon]

i could have sworn i read that timing mark had to be 30 degrees before dead center for all the intake valves to be closed?

think about this intake valve are not closed when the engine is running and it makes boost right? Intake valves doesn't have to be close to do a boost leak test. The piston rings is where boost is built not valves. Now valve timing determine how quick or slow boost is built up on a running engine

 

[BogusSVO]

Doing a BLT and he get air past the cam seals?

Compressed air from the inlet of the tubo all the way thu the IC pipe, The Ic and the intake, and 1 cyl will have the intake valves open to some extent. Even with the engine at #1 TDC, another set will be open.

Yes I can understand a small amount of air getting past old hard valve seals or worn guides.

The only way I can see enough air passed to cause air out the cam seals is bad rings....

Thr BLT air down the inlet track into the head, inti the cylinder, past the rings, into the crankcase, up the oil return ports in the head then out the cam seals...

But if this is the case then it should pass out the dipstick tube, the oil filler caps, maybe the PVC valve on the cover...

Something dosnt sound quite right....

 

[scottyhops]

think about this intake valve are not closed when the engine is running and it makes boost right? Intake valves doesn't have to be close to do a boost leak test. The piston rings is where boost is built not valves. Now valve timing determine how quick or slow boost is built up on a running engine

ahhhhh this is true! thanks for that!