Boost leak question?

[Lord Tauk]

I've never owned anything with a turbocharger before so identifying sounds inside the cab is somewhat a challenge to figure out.

However, I don't have any aftermarket gauges yet but when my turbo spools up it sounds like a normal whistle except when it really builds boost practically at or close to WOT it sounds like "WHOOOOSSSSHHH", sounds like air leaking out of something fast, when I lift off the throttle I can hear the turbo spool down to it's normal whistling sound. I was told this was a boost leak, but I've checked out at all the boots and intercooler piping just with my hands, everything seems tight? Im sure they can flex when under boost and leak, but I don't see any oil blowing out?

Truck doesn't really feel to be at a lose of power either. Completely stock except for what looks to me as a K&N drop in filter in the box. I haven't completely removed the filter, from the looks of it at the top, it doesn't seem dirty.

I ran some searches, I've read that whoosing sound results in turbo surge upon lifting off the throttle?

 

[Race22]

At WOT I can really here the air going into my filter. The K&N will let you hear your turbo Little more than normal. To me it don't sound like you have a leak. Since your truck is stock, if you did have a leak, it would defiantly show some oil stains on the pipes where the leak was.

 

[Lord Tauk]

I'll do a little more investigating tomorrow. I didn't think about what I was hearing was air rushing in the filter.

I don't have any fresh oil anywhere where the pipes, clamps, etc. etc., I was planning on ditching the K&N and the factory box to something that can filter better, but it just occured to me that maybe what I was hearing was a boost leak.

For more diagnosis, I don't have any black smoke or any colored smoke blowing out the exhaust when I hear this, Im sure the ECU would be maxing fuel tables even with a boost leak? So it's not like I'm overfueling boost that should be there but it's being leaked before it goes into the cylinders.

 

[Lord Tauk]

I made two quick videos with my digital camera, not the best quality but it'll work somewhat better than I can descrbe. See what you guys think.

http://s42.photobucket.com/albums/e329/PSTROKE/?action=view&current=Picture091.flv
http://s42.photobucket.com/albums/e329/PSTROKE/?action=view&current=Picture092.flv

 

[pmrpete]

I made two quick videos with my digital camera, not the best quality but it'll work somewhat better than I can descrbe. See what you guys think.

http://s42.photobucket.com/albums/e329/PSTROKE/?action=view&current=Picture091.flv
http://s42.photobucket.com/albums/e329/PSTROKE/?action=view&current=Picture092.flv

My truck does something like this also, but it's more pronounced when it shifts or when I let off the throttle after getting into it a bit. From what I understand, it's just air that has been suckd in and has nowhere to go so it's exiting the intake and nothing to worry about. Not sure if that's exactly what is going on with your truck, but it does sound llike that's what it is. My buddy's 6.0 makes this type of noise as well. Hope this helps.

 

[Lord Tauk]

I've looked again, no fresh oil anywhere. Where would the oil come from to blow out through the intercooler piping boots? Crankcase vent?

 

[DaveBen]

Yes the crank case vent system.

Dave

 

[dpantazis]

best way to track down the leak is with a pressure tap. budro had some pictures. dieselsite.com has one for sale, $60 i think that EVERYONE should have one of these to track down boost leaks. components depend on where you decide to pressurise the system.

i used a 4" PVC male to 1-1/2" female adaptor. then 1-1/2" reduced down to 1/2". then a ball valve, a small pressure regulator and gauge to QD fitting. ~$40 in parts if you ahd to buy all new, but you probably have some of these you could use. the 4" PVC adapter need to be turned down about 1/4" in diameter to fit the OEM air cleaner hose.

either way, hook it up, then close the regulator so no pressure passes. open the ball valve. open the regulator to about 5 psi for 5-10 seconds and close the ball valve. the snorkle should 'inflate'.

listen for the leaks. system will hold pressure so you can go around and check for leaks. sometimes you can snug clamps a little bit and stop them. best thing to do is take apart and clean, reassemble and tighten up.

i think budro used a 3" PVC adaptor and a 3" furnco type coupler to mate to the turbo directly.

dennis

 

[Lord Tauk]

Sounds good about that custom made leak testing method.

How does my turbo sound in the upper RPMs compared to you guys? I'm more used of a high pitch whistle even at full boost versus my "SHHHHHHHHHH" sound, that's why I thought there might be a leak.

 

[Got Diesel]

It's hard to tell but to me it sounds like a leak. I know this because I had one for a long time. Has the sound just recently come to your attention? Check the orange boots that go from the intake plenum, to the intake manifolds, make sure that all these clamps are tight, cause they will leak when the boost builds. What kind of boost do you build?