Laust Pedersen

My boost had gotten a little difficult to build lately and at high boost there was a wheezing sound from the engine bay, probably some sort of leak.

I then started doing the usual intake system pressure test (from the J-boot) listening for leaks, but only found the oil filler cap leaking (crankcase being pressurized through the PCV system’s outlet to the J-boot).

I was then prepared to take the intake manifold off and inspect all the lines and connections, but before getting that far noticed a small amount of oil under the intercooler inlet joint. Adding 2 and 2 I took the rubber coupling off and sure enough, there was the bare visible crack at the bottom of the coupling. In the picture I tightened the hose clamp to make the crack more visible.

My point with this post is just to show how subtle and difficult to detect some leaks can be. Another point is how much diagnostic information there is to just listening to the engine and make some educated guesses for the source.

Laust (back in the boost business)

UK952

Same thing happened to me on a 6 month old coupling, put the old one back in and its still fine. Oil in that area was the clue wonder if I would still see it now I have a catch tank.

Tony

(PS happened to a friend a few months later also with a nearly new coupling)

testarossa_td

Yup a lot of people complain about the little bit of oil that is in our intake system, but for older cars...follow the oil and it shall reveal all

DanG

Are you guys using a PVC cap with a schrader tire valve or compressor quick connect installed to pressure test the intake system? You just remove the clean air tube from the turbo inlet and clamp on the cap, then pressurize it to 20psi and listen for leaks (engine off). It makes finding leaks like this REALLY easy. If you can hear it but can't find it, you just brush on some soapy water and find the bubbles.




You can make them yourself for $5-10 from Home Depot...
http://www.vfaq.com/mods/ICtester.html
http://www.1baddsm.com/DIY/pressuretester.html

Cra$h

I did that a couple months ago and found my ISV was leaking substantially through the crimps on the body.

Installing an inline pressure gauge before the schrader valve on the tester would be pretty handy too.

UK952

Pressure tested it since and my ISV was also leaking really badly, I have deleted it for now but may need a new one for the winter, need to test again now thats done,
Tony

DanG

Cra$h, how about some more pics of that super high-dollar car of yours? That think looks like a million bucks! (This is gielamonster from the eVil board.)

And you can also just use your (aftermarket) boost gauge. Although the on-cap gauge would be easier to make sure you don't over-pressurize it.

cpt_koolbeenz

If you need a new connector I have one extra.

333pg333

This is a common problem for our cars. Mine's blown/split 3 times. I am going to get one of the Lindsey silicone kits or some variation of. Maybe when we do mods and up the boost this is one of the frail parts that suffer?

2bridges

great tid-bit of info. Appreciate the tip on leak testing........ cannot believe I did not think to do this

Eyal 951

I switched over to silicone and T bolt clamps. Its a worry free mod.

hosrom_951

This is very nice as well:


(click on the picture to follow link)

Eyal 951

When I tested my system, I got the proper size PCV cap (rubber) that fits right over the IC opening and is tightened down with a hose clamp. I put a wheel valve stem in the middle and compressed the system that way.

DanG

Good link hos, it figures Bruce would already have a tutorial on this.

http://www.arnnworx.com/boost_testing.htm

hosrom_951

Laust: I noticed something with the oil filter cap, perhaps you can help me on this issue.

I got a new filter cap, which comes with a new seal, and i have some hoses from the AOS to the j-boot exposed since i had a catch can insalled, which is temp. not installed due to some reasons.

Anyways, i apply air pressure (with my mouth) on teh AOS, and a loud hissing sound comes and i can feel the air getting past the oil filter cap. Now, when the oil filter cap is half tightened, it seals almost perfectly and i can feel some pressure resistance on the hose (since i am using my mouth), when the cap is tightened, it leaks.....there are no cracks (visually) on the AOS, any i deas?