Help: Intake leak result/turbo noise

[Michael Cummings]

I've had a boost leak for along time now, I used to have the car set at 18psi, then one day it went to 15 then to 12, ever since I have not been able to boost over 12psi, even though everything was still set for 18.

So today I finally got around to doing an intake leak test, I made a tester to block off the turbo with a valve stem and used compressed air.
Right away I found where the leak was.  It was drasticaly coming out from the j-pipe from the turbo outlet, so badly that it wouldn't even go through the rest of the intake system.  I could put my hand around the outlet, fire air in, and it would be coming right out from the area, and strongly push against my hand.

So I took off the jpipe, and saw that for some reason on half of the gasket was even there, it had broke in half somehow.  I phoned up chrysler they discontinued that gasket, so I made out of of a sheet of gasket material, it turned out really nice.  I put some gasket dressing/sealent on both sides and put it all back togeather with the new gasket.  

I then tested it again, and for some reason air was still coming out, so i cranked down on the two bolts a bit more, and air still comes out, but now only through one side, so I guess it fixed a little bit of the leak?  I have the bolts pretty much as tight as they will possibly go, any tighter and they will most likely break or strip.  And a brand new gasket with sealent, and air is still pouring out from there.

So I took the car for a spin after hooking everything back up, and now the turbo sounds reallyyyy different.  It has like a high pitched noise now, almost like a kazzoo.  Bov still sounds the same, but the turbo like screams really high pitched like now, which it never did before.

And I can now boost up to 13/14psi, but still not up to the 18 that I could before.  So i'm pretty confused about the turbo , maybe i fucked it up somehow with the compressed air? I have no idea, and I have no idea why air is still leaking out from the turbo outlet.

Any help/ideas, comments etc would be much appreciated.

[Kevin Chan]

did you check the J pipe itself? or any couplers?

[Mike Schmid]

If you put a gasket with sealant on there and you're still leaking something must be warped or the bolts are fubar.

Pull it off again and check both the turbo and j pipe flange for true.  Inspect the bolts and bolt holes too to make sure you're not running out of thread or running into a burr so that the bolts are tightening up when they aren't actually clamping the flange down.

[Michael Cummings]

Yea i'll do that, it was also reccommended to me to try using straight silicone with no gasket.

This all makes sense.

But what about the weird sounding turbo now? thats what freaks me out the most.
The car does feel like its pulling harder than it was before now though, so I dunno whatsup with the noise.

[DarrylDhaliwal]

my turbo make that same screaming sound but i can still boost high. I also want to now what that sound is

[John Hartman]

when you had that huge leak, your turbo was still trying to make 18 psi at whatever larger than stock flow rate you are running.

Now, it went down to 15, then 12, like you say.

So, I figure that the poor thing has just gotten way way tired of working so damn hard and has decided to put itself out to pasture.

[Mike Schmid]

Sound could be like John said, the turbo is getting tired from being majorly overworked trying to pressurize the entire atmosphere.  Or, now that it doesn't leak as much it's not working as hard and the sound is different and you're just not used to it.  

I don't know for sure but I'm suspecting with a big leak the turbo has less load on the compressor wheel so given the same flow across the turbine it'll the whole thing will spin faster.  Or so you'd think.  Now I know in some big turbo diesel yachts the turbos are setup so that at higher rpm cruising speeds the turbos spin fast enough that you stop hearing them because the pitch goes higher than what the human ear is capable of.  Maybe you're having the same thing where the turbo rpm is coming down so the pitch is dropping and seems to be getting louder.

I would work on getting those leaks fixed and give the compressor but a wiggle and a spin to see what kind of shape the turbo is in.

[Artem Goloubov]

Take the intake pipe off, check if there is a compressor wheel play in your turbo, move the compressor side to side with your finger. If it moves alot than your turbo is gone. Turn the compressor wheel, check if it scrapes the housing, if it does than turbo is gone.

If the whining noise is changing with the boost, than the compressor wheel is most likly scraping the housing, and your turbo must be replaced or rebuild.

Art

[Michael Cummings]

The sound doesn't change with boost, its just a different more high pitched sound that it was previously.

It was at 18, but then when it dropped to 12, i cranked the mbc back to set it for around 12/13, so that the turbo wouldn't be working so hard.

I think i was driving the car for about 1-2 months at most like that, and its a brand new small16g with only about 20k km on it.  Aswell after partly fixing the leak the car pulls noticeably harder.  

So i'm thinking/hoping that the turbo sounds differently in a good sense, in that it doesn't have to work as hard now.  I would think if the turbo was shot that it wouldn't pull harder than did previously?

I will attempt to fix the leak again today and post result.

[Michael Cummings]

I have found the culprit.
Zero shaft play with turbo and blade spins perfectly, so turbos good to go.

And I found the problem, the J-pipe flange is warped like a mother f**ker.  So extremely warped that you can easily see it with naked eye and little to no effort.

So can I just go to local machine shop and have it machined flat??  Or how do I go about this?

[Mike Schmid]

If it was me, and it was a stock J pipe and it was warped real bad I'd stick it in a vice to straighten out a real bent ear, then I'd belt sand it til it's uniformly flat and hit it with the random orbit to smooth it out so it seals nice.  But that's me, and I figure it ain't worth spending money on stock stuff like that.  A machine shop should be able to do it but they'll charge ya.  If it was too bad I'd upgrade to SS.  If it's SS, I don't know how workable it is, maybe talk to someone who works with that stuff more.

[Andrew Scott]

Get another stock one? I'm sure SOMBODY has one lying around. Ask Wade? He bought my j-pipe off me a while ago, and I'm guessing he'll use it eventually.

[Michael Cummings]

yea i ended up buyin wades old one off him.  The silicone is drying right now.

[Michael Cummings]

I just finished puttin the new jpipe on with permatex silicone for the gasket.

The flange was nice and flat, i cleaned both mating surfaces up with some light sanding/cleaning.

Took it out for a spin, and the car seems to be driving alot smoother, i still cant get it past 12psi though for some reason, I opened the mbc fully, and wont go past 12, i close it almost fully and wont go under 12.  Maybe the mbc is screwed?

The turbo now , doesn't make any noise, at least I cant hear it over the exhaust, bov still sounds same.  It used to be really loud, then it switched to really high pitched after partially fixing the leak, now its almost silent.

I haven't had a chance to retest to see if its still leaking yet.

Weird how the turbo sound has been changing so much, i dont know why its silent now.

[Mike Schmid]

Another thing is a leak can make noise... alot of noise.  Ask John Hartman about the "subtle" whistle we got out of his car when we pressure tested his intake   :wink: