turbo noise

[19Kgvw]

I'm need some help... ... ... .



A few months ago I started hearing a weird noise while making boost. It was fairly quiet and not to noticable. Recently, I changed out the stock air box and K & N filter with a ASA modified intake pipe and an AFE filter (stock box is gone).

The noise is much more prevalent due to the new intake and is easier to describe now. The noise sounds like a "flutter" or like a propeller "cavitation". It only happens when boost is building but isn't at all consistent. Sometimes the noise will happen, sometimes it won't. Sometimes it will happen at 12 psi and other times at 20 psi. I can back off the gas and drop boost and noise will stop, then re-gas, boost will build but this time the noise won't come back. It seems to happen more when I'm pulling a good load. Weird.....

The boost doesn't fluxuate nor is the power any different when it's noisy... so performance doesn't seem to be affected.



So, any ideas? thoughts?

Rich

 

[Greenleaf]

I hear this is a problem with "some" compressors. PDR will tell you that there is a particular wheel that is noted for that. HTT told me I would have no problem with my (current) compressor as I had inquired about the same. It seems to effect the 60 mm wheel of a particular orgin. If you don't have this wheel, perhaps it's a distant relation.



Do you know for certain what turbo/comp. wheel your engine has???



GL

 

[ARedetzke]

My old H1C used to do that same thing. I figured the bearings were going out, so I swapped it out for an HX-35 that a friend had laying around. Once I got it out, there was no play in the bearings, so I'm assuming that the turbo is fine. Don't know why it was making such a racket

 

[Bob Beauchaine]

What kind of a hot side are you running? Is it wastegated - if so the wastegate can "flutter" under certain load conditions. You can see that on your boost gauge.



Bob

 

[swankmetal]

what you've got, is one of these. a stock h1c compressor housing. what you need, is of these. if you have, or have access to a lathe, it's a pretty easy diy job. if not, you should be able to get a new housing from high tech turbo or piers. OR, if you can find a wh1c, or early hx35 compressor housing (the clamp on style, not the kind with an internal snap ring) on ebay or the local junkyard, it'll clamp right on there. if you're going to do it yourself, pm me for details. anyway, WHY you need this (and this is to be taken with a grain of salt because it just what i've gleaned from this and a couple other sites) is that your compressor IS "cavitating". it's trying to push too much air into the engine at too low of a shaft speed, so the air comes back through the wheel and makes for a great disturbance right at the blade tips. the slot that needs to be cut will allow this "wrong way" air to come back out without passing by the tips. and all is well.



dave

 

[JLEONARD]

What Dave said... . I had it and solved it by installing a housing from a WH1C.

Jay

 

[Greenleaf]

I have not experienced that situation when I had the H1C, however I generally do not tow. There is a local member who has the MW slot in his H1C and (eight vane) 60mm comp. wheel and still has the flutter at times when towing.



Scott

 

[19Kgvw]

what you've got, is one of these. a stock h1c compressor housing. what you need, is of these. if you have, or have access to a lathe, it's a pretty easy diy job. if not, you should be able to get a new housing from high tech turbo or piers. OR, if you can find a wh1c, or early hx35 compressor housing (the clamp on style, not the kind with an internal snap ring) on ebay or the local junkyard, it'll clamp right on there. if you're going to do it yourself, pm me for details. anyway, WHY you need this (and this is to be taken with a grain of salt because it just what i've gleaned from this and a couple other sites) is that your compressor IS "cavitating". it's trying to push too much air into the engine at too low of a shaft speed, so the air comes back through the wheel and makes for a great disturbance right at the blade tips. the slot that needs to be cut will allow this "wrong way" air to come back out without passing by the tips. and all is well.



dave

Bob... . what do you mean by "hot side"? I'm assuming you're talking about my exhaust housing. Every thing is stock, but I'll check for any housing information.



So gentlemen... ... ... . another question... . looking at the pictures that Dave provided, the difference that I see is a machined groove on the OD of the inner machined bore. Am I seeing the right thing?

Does this cavitation hurt anything? Like breaking or slowly fatiguing the blades? To me, it is definatetly distracting and I want to back off the go pedal... ..... (hate to do that and lose my momentum up the grade).



And another question... ... why would this start recently? The truck has 122K on the odo and I've had it for 6 years..... it never made this noise before.

Did the WH1C come on any certain models or years? Is the compressor different on the WH1C vice the H1C?



I know I've got a lot of questions and no answers but I want to understand this. It's just what I do... ... ... .



Thanks for being patient with me, Rich

 

[JLEONARD]

Did the WH1C come on any certain models or years? Is the compressor different on the WH1C vice the H1C?

The 94 and some early 95 trucks had the WH1C. Yes, the compressor wheel is larger in the WH1C.

Jay

 

[19Kgvw]

Update on this issue- I spoke with Mark at PDR, and was told that the likely cause of the noise is that the compressor wheel shaft bearing are starting to wear. This allows a slight movement of the compressor wheel. And with the 1HC design causing a aggravated air flow at into the compressor, the air disturbance can cause the wheel to vibrate and make this noise.

So, with that said, if gives me the opportunity to upgrade the exhaust housing to a 16cm and the compressor to the HX-35 hybrid. Wa-hoo!

I'll drive it for the summer and have this for my fall project..... it was something that I'd wanted to do anyway to finish the up-grade to the motor.



Rich