Boost leak, only holds 4psi...cant find leak!

[FullthrottleGST]

did a boost leak test earlier and its only able to hold 4psi. its leaking from the valve cover gasket and a little of the jpipe. but theres another one i cant find, seems to be leaking the most. its down there by the alternator or somewhere around there. i mean i dont think there are any intake line area down there that would cause it to leak like that.

any ideas?

 

[president95]

Licp?

 

[MrBoxx]

Spray soapy water to nail down the rest of your leaks. Likely places: Intercooler pipes, throttle body, BISS, intake manifold, turbo, intercooler. If you're hearing air leaking from the exhaust area, it's possible that you have an exhaust leak at the O2 housing, downpipe, turbo, or manifold.

 

[CyberEye]

You really really shouldn't be having any leak from the valve cover gasket. Hopefully it's just your valve stem seals. But if you're hearing air from down by your alternator, it may be blowing by your oil filter. If that's the case, you've got some bad rings. Which would also explain the valve cover.
I'd be doing a compression check.

 

[patty AT forge]

How did you perform the pressure test?
Do you still get the leak from down below with the throttle closed, if so there is a good chance that the blowby theory may not be the case... I would try a leakdown.

 

[joe]

check your pcv valve also

 

[oldman]

did a boost leak test earlier and its only able to hold 4psi. its leaking from the valve cover gasket and a little of the jpipe. but theres another one i cant find, seems to be leaking the most. its down there by the alternator or somewhere around there. i mean i dont think there are any intake line area down there that would cause it to leak like that.

any ideas?

It's probably leaking out of the oil dipstick tube which is the same leak as the valve cover gasket leak, what most call crankcase boost leak, boost pressure leaking into the crankcase. Boost pressure can enter the crankcase in four ways.

1. Turbo seal, perfectly normal during a static pressure test as long as the turbo has no excessive shaft play or dumping oil during normal operations.

2. PCV valve.

3. Intake valve seals.

4. Piston rings.

I have some questions for FullthrottleGST,

1. What led you to the leak test?

2. Are you smoking out of the tailpipe?

3. Does your dipstick pop out under heavy load?

4. How's your pcv and breather routed?