Boost leak sources

[BLOHS7844]

I'm just wondering if I can get some help compiling a list of all the possible sources of boost leaks. If u have ever had a boost leak in some location or know of someone who had one I would appreciate your response.

Obviously couplers in the intake are a major source. The seals on the throttle body, vacuum hose, cracked intake pipes/intercooler, BOV, and the intake manifold to block come to mind. Anything else?

 

[slayerphoenix]

I'm just wondering if I can get some help compiling a list of all the possible sources of boost leaks. If u have ever had a boost leak in some location or know of someone who had one I would appreciate your response.

Obviously couplers in the intake are a major source. The seals on the throttle body, vacuum hose, cracked intake pipes/intercooler, BOV, and the intake manifold to block come to mind. Anything else?

pretty much those are all the spots. the easiest way to find a leak is to check your Boost gauge to see if you are losing boost. then once you know that open your hood and listen for any major leaks, then start from the the intercooler and follow the pipes back look for any smaller leaks. the way to prevent the leaks from happening are to make sure all your connections are solid and all you clamps are tight. I was working on a Supra late last year in my school auto shop and it had a crack about 5inchs long in the intercooler piping at the turbo. It was blowing so much air up past the manifold. Once we fixed that the boost was back to normal. Thats honestly the best way to do it

 

[GRAVEDIGGER]

Obviously couplers in the intake are a major source. The seals on the throttle body, vacuum hose, cracked intake pipes/intercooler, BOV, and the intake manifold to cylinder head come to mind. Anything else?

I fixed your list above ^^ and to add one more big one that is very common are the injector seals, where they fit down in to the intake manifold.

The stock PCV valve can let boost leak back in to the crankcase so be aware of that too!
A good idea is to add one of these check valves in between the stock pcv valve and the intake manifold to prevent boost from making its way from the intake manifold to the crankcase.
3/8" Kynar® Standard Check Valves | U.S. Plastic Corp.

See here too for more on the PCV system.
http://www.dsmtuners.com/forums/articles-engine-fuel/366890-4g63t-pcv-system.html

 

[Backinajiffy12]

+1 on injector seals

BISS Screw, BC

 

[LandoAWD]

pretty much those are all the spots. the easiest way to find a leak is to check your Boost gauge to see if you are losing boost. then once you know that open your hood and listen for any major leaks, then start from the the intercooler and follow the pipes back look for any smaller leaks. the way to prevent the leaks from happening are to make sure all your connections are solid and all you clamps are tight. I was working on a Supra late last year in my school auto shop and it had a crack about 5inchs long in the intercooler piping at the turbo. It was blowing so much air up past the manifold. Once we fixed that the boost was back to normal. Thats honestly the best way to do it

...or perform a simple boost leak test.

Interesting first post...

 

[BurrowZ]

The throttle body is a huge boost leak-prone spot:

BISS O-ring
ISC O-ring
Shaft seals
Gaskets (blown, put on backwards, not sealing)
Lower TB Gasket (FIAV)

Although uncommon:

Brake booster
BOV diaphragm
Wastegate diaphragm
AFPR diaphragm (although this will cause more than boost leak issues)
Compressor housing seal
Boost gauge

More common places:

Couplers (Lack of T-bolt clamps or beads on IC piping)
Throttle body spots listed above
J-pipe gasket
Vacuum lines
BOV (esp stock 2g)
Intake manifold gasket
BOV gasket
PCV valve
EGR components
Injector seals

And if you made your own tester, you could have a leak at the tester itself, usually where the valve stem is.

I missed a bunch I'm sure, but you get the idea. Soapy water is your friend

 

[slayerphoenix]

well thats what i was getting at. i just explained myself for him, or anyone else for that matter, who didnt know.

 

[sciondan]

A big one for me was the stock intercooler inlet pipe. The aluminum tends to corrode there and in my case actually had pin holes.

 

[NHerron]

Make sure when bangin out the boost leak test, to put the engine at 30* ATDC. That way, the valves won't be in overlap and air won't leak out of the exhaust.

http://www.dsmtuners.com/forums/newbie-forum/321580-how-set-motor-30-atdc.html

30* ATDC would be about 2 inches counter-clockwise from the mark in the crank pulley, lined up to the 0* mark on the plastic cover.

 

[BLOHS7844]

How the hell do u move crankshaft?

 

[NHerron]

Turn the wheels over to the left to acess harmonic balancer. Take a socket and fit it over the largest bolt in the middle. I didn't have a metric socket that fit so I used a standard 7/8" socket with a 1/2" ratchet. You can also just use the square drive of a standard 1/2" extension

Picture (don't mind the red circle, it's a borrowed image)
http://img.photobucket.com/albums/v641/effinwill/IMAGE_003.jpg