boost/vacuum leak?
 

I think I have a pesky boost leak that I can't find. I have a squealing sound I realy don't know were it comes from since I haven't had the car on a dyno and sounds are deceiving when heard from the drivers seat.

it happens at mid to low load, off boost. when I put my foot down it goes away but I have fluttering boost at high rpm.

I have checked my piping and hoses and it all seems good apart from a couple of very small pin holes in some of the welds that may be leaking. I tested them by placing a drop of water on them at idle thinking if there was a leak the drop would be sucked in. the ones I tested didn't suck in the water. but there were a few in hard to get places I might have overlooked.

I have a check-valve on the air thingy hose (forgot it's name :spank: )

there any places on the manifold that can leak?

You need to pressure test your system with an air compressor. www.boostpro.net/prodtester.html has a tester tool (universal tester), or you can make something similar out of hardware store parts. You would hook up the air compressor, pressurize the system, then listen and feel for air escaping. Spraying soapy water around the engine bay and looking for bubbles helps too.

that looks easy to make. with a 2" and a 3" version I could test the system in sections and narrow down where the leak is.

wonder if a vacuum cleaner on blow would work with the soapy water idea???

I have a boost leak - I think . Lost abot 2 psi from system after some accidental high boost runs . 14 psi - eek !!!

you can give it a go. tell me if it works :lol:

the leak you describe sounds like it has happened to a few people after a boost spike. I'm trying to avoid taking the upper manifold off in search of it but under it is where I think mine is.:banghead:

Pin holes can be all it takes. Duct tape to the rescue!:lol: j/k

yeppers - works bloody well . I wrapped a rag around the vacuum cleaner tube and shoved it into the intake pipe .

Found 1 largish boost leak and 3 smaller ones . 3 of them around the blowoff valve . I was quite surprised to discover how what looks like a small leak can actually drop your boost considerably .

In fact I would go as far as to say that anyone fitting FI should do this as part of the install .....

I bet your idea sucks if I use it to test for vacuum leaks:lol:

well it would really suck if your vacuum wont blow :lol:

Vac brake bleeder works well to test for Vacuum leaks.

I use mine all the time.

I need to brake down and get a shop vac to try this for boost!

wouldn't pressure be better to find a leak (vac or boost) as the key to it seems to be the bubbles from the detergent spray bottle ...

Sometimes vac leaks are diff than boost leak since each type of air pressure can cause different stresses on the parts.

Vac leak I use the gauge to tell me if I have on and then finding it can be fun!!! ;)

A loose clamp on a hose will suck to the pipe in vacuum, but flap like a flag and sound like a fart in boost.

Just sayin.....

S

I finally decided to try and find the leaks this afternoon. boost leaks first. I rigged up a pressure system out of a couple of bits of round nylon rod. one to blank off sections by clamping it to a coupler in the system and another with a line in the end that could be attached to my bicycle pump since it had a gauge. I found one leak on one side of the intercooler on a joiner. just a small one @ 15 psi. and it took ages for the system to loose pressure.

I'll try a vac hand pump next.

should the upper manifold hold pressure?

With the engine off? Hard to do unless you can seal the exhaust.

Is there anywhere under the upper inlet manifold that will spring a big leak . I still seem to be losing about 1 psi from somewhere ....

The Solenoid braket / resevoir....?

And the Fuel Evap - those are the only things down there... unless you have a leak on the manifold itself.

there is a on way check going to the solenoid reservoir and that is still connected so i don't think it is that - i'll check the evap .

Call around to local shops to see if anyone has a smoke machine. It wont produce a lot of pressure but the smoke can usually find its way out of even the smallest hole.

/\ good idea - i could shove a flare up its date - heh

Dry ice in the tailpipe??? LOL

you and your damn avatar brettus...I keep thinking you are jedi

do you miss my melons ?

Brettus, I had a fairly good leak around the blanking plate after I put it in, during Greddy install - the problem is that the plate cants the whole manifold due to it's thickness. I got a leak at the throttle end, but you can also get a leak at the 'ports' end because it is now not mating flat with the LIM.....

S