Pressure cooker sound

[CRWilliams]

I posted a while back about a fluttering sound and noone could come up with what it was. It is finally getting worse and now I have had some other people listen to it and noone knows what it is. It sounds very much like a pressure cooker, and the needle in the boost guage flutters when it does it. I know it is a boost leak, I can hear the whoosh, then the whistle, then it makes the pressure cooker sound. I was wondering if maybe the wh1c turbo wasn't meant to handle the boost I'm making( I can fairly easily peg the 30psi guage in 4th and 5th, I blocked the waste-gate to see if it was the problem, I had the waste-gate set to 29lbs. ) I was looking at a diagram of the turbo and noticed two rubber o-rings on the compressor housing, could one be bad. Or would I be better off just changing to an hx35 or something? HELP, this thing is driving me crazy.

 

[Lil' Dog]

Maybe the intercooler popped a hole???? I don't know what pressure rating the IC is good for but maybe you blew it up???



Other than that maybe the intake plenum gasket on the rear plate may be loose.



I have a hard time thinking its the turbo. But, stranger things right??



J-eh

 

[Sled Puller]

I blew my boost guage line off, but before it went, in made funny noises at high boost levels.



Could be head gasket also.

 

[CRWilliams]

Am REALLY hoping it is not a head gasket. The boost guage hose is on the drivers side. The noise seems to be coming directly from the area of the turbo. Everyone who rides and listens out the window says it sounds like it is coming from the right front wheel well. I am taking the compressor side of the turbo apart tomorrow, if the weather isn't too cold. Has anyone done this, how hard is it. I have been told it is really easy. Anything I should look out for? Thanks for your help.

 

[Sled Puller]

Now it is REALLY sounding like a head gasket!



Any oil in your overflow bottle?



Gene

 

[ScottB]

I would not freak out just yet. I have had that noise for a long time and it comes and goes with the different conditions. When I posted my problem or the pressure cooker noise no one had any ideas. I have come to believe it has to do with the amount of air flow available to the turbo. I say that because I put a Big Honken air filter on and I just about never hear it anymore. In fact I have to get the conditions just right to hear it at all. I really dont think your headgasket is bad. Hope this helps.

 

[CRWilliams]

ScottB, I used to think also that it was the air filter, that is actually why I opened up my air box. I can't believe that the K&N doesn't flow enough air, but to check I put the stock filter back in for a couple of days. The noise didn't change one bit, but I did loose a couple of pounds of boost. I also can't figure how the filter would cause the boost to flutter, but goes away at higher boosts where the turbo is flowing more air. I will check my overflow today, but I dont think there is any oil in it, I check it pretty regularly for coolant level, and I have had this noise for going on 8 mnonths now.

 

[CRWilliams]

Pulled the large part of the compressor housing off today. The shaft has a lot more play than I thought. There is no discernable play front to rear(end play), but side-to-side(radial?) play seems to be pretty substantial. Obvious enough to see with the naked eye. Is this an OK condition?

 

[ScottB]

See thats what I don't get if the turbo was bad it should have blown by now, right. Like mine its been doing it a little for ?couple years. Thats either one tough turbo or somthing else.

 

[A Johnson]

The side to side play is normal, if the compressor fins aren't touching the housing when you push sideways on the shaft then you are good to go. There shouldn't be more than 2-3 thou end play so I would say you are good to go. I would have to get the book out to give exact figures, these are the guidelines I use on a day to day basis. Oo.

 

[KEENO]

KEENO swoops in from Leftfield....

Hey Mprtrpr!



This suggestion is probably way out there in Leftfield but I'm going to swallow my pride & post it anyway. I know that you said that noise is coming from the Rt. Frt. Wheel area and you have the turbo off currently.



If the sounds persist after the re-install... . Check to see if what you're actually hearing is the needle rattling in your Isspro Boost Gage. I know this sounds ridiculous but I thought I was having "wastegate flutter" on the turbo... Sounded exactly like the "tick,tick,tick" of a pressure cooker! It was actually the "Banks" Isspro Boost Gage.



I hope you didn't hurt yourself when you fell off of the chair laughing.



KEENO

 

[CRWilliams]

Hey Keeno, not laughing at all. I am up for anything at this point. After the sound started I actually did look at the boost guage, hey if the needle is sticking or fluttering it might be the guage right? Anyway, the noise is definatley coming from the right front floorboard, fenderwell area. I'm still looking.

 

[KEENO]

I would of swore my 'pressure cooker' sound was coming from the other side of the firewall near the passenger floorboard. Would of bet $100. 00 it was the turbo wastegate bouncing on the seat @ 20 PSI!



Totally eliminated the wastgate and still had the "ticking"... . It's was the gauge.



Let us know what you find...



KEENO

 

[Lil' Dog]

How about the clamps around the housing, brake etc. on the exhaust. Maybe the exhaust brake has a leak around one of the bushings?? Or maybe the brake doesn't like the huge abouts of exhaust goin through it LOL!!



Maybe the diaphram in the wastgate is blown???



I can't figure what else it would be.



J-eh

 

[Mgrant]

Hi All,

I decided to revive this thread to see if anyone figured out what this "pressure cooker" sound is. Mine has been making it ever since I installed the BHAF. I experienced all the other good benefits of the BHAF, lower EGTs, less smoke, more power, but this annoying sound appeared. I thinking that it could either be compressor stall or just plain engine intake noise, but it does it at only at low RPMs (between 45 and 50mph in 5th) and above 12psi boost. The sound totally disappears as RPM increases or if I let off the throttle. The engine pulls great while doing it and very little smoke, if any. All other times, the engine purrs like a kitten. Any thoughts?



Mike

 

[nascar mark]

Have you checked the underside of the exhaust manifold for a crack with a small mirror. Manifold cracks will open and close some with different temps so you would see a fluctuation in boost numbers. Also check boost hoses for cracks. Pressure test intercooler too.



mark

 

[Mgrant]

Hi Mark,

I checked the manifold and all the exhaust ports and didn't see any evidence of a leak. The only leak I can see is the butterfly shaft on the BD brake. I've replaced all the rubber hose connections, but I have yet to pressure test the intercooler. But it's funny that it only does it at a very narrow RPM window. I think it's comming out of the intake, so I'm going to put the stock box on and go through a process of elimination. If it is comming from the intake, I'd think it could be some sort of compressor stall or just plain engine intake noise. It's it's combustion noise, an advance of timming should help that, mine is still set at stock. I haven't seen any fluctuation in boost numbers like mprtrpr did, they act normal. And with the BHAF, it takes some effort to even get it up to 900 degrees. It's been 15K since the valves were adjsuted, so that shouldn't be a problem unless they did it wrong. If you have any other ideas, keep them comming. I'm always looking for suggestions. Oh yea, what does the overflow valve do and where it is located?



Mike

 

[Mgrant]

OK, I conducted a test and temporarily removed the BHAF and put the stock airbox back in and the sound totally disappeared. Boy, she did loose response with the stock airbox and filter!Anyway, so now that these sounds are comming from the intake, what could they be? I'm thinking that these noises could be the tips of the turbine blades going supersonic. At the higher boost and rpms levels, the "sonic booms" could be getting sucked into the engine and not out the intake. I do know that about the fluttering sound boost level, the turbo hissing turns into a steady whine. Any thoughts?



Mike