samadkins29 Posted September 23, 2008 Report Share Posted September 23, 2008 Hey, so here is the complete story. My 98 s70 GLT had 208K miles on it when it started making this flutter noise every time I let off the gas. I was very sure my turbo had finally bitten the dust as I had put in a mbc and was running 13 psi two weeks prior to the noise. Once the noise started the psi never really went above 9. So I went and bought a used 16t(had some shaft play) That turbo made the same noise and once again never really went above 9psi even with the MBC unhooked. HERE is a video of the noise: ITS NOT MY CAR- THIS GUYS TURBO IS MAKING THE SAME NOISEhttp://www.youtube.com/watch?v=v40jLAJx314When he lets off the gas you will hear a fluttering noise. That is the noise I got with both turbos. Both turbos had shaft play so I assumed that it was the compressor wheel hitting the side when I let off the gas. His cure was the intake manifold gasket was broken, could that be the cause of my problems? Thoughts?I also checked the cbv on my original 13g, only to find it looked new with no cracks or tears. The cbv was my second thought of what could be making the noise. On a minor note my 16t is leaking oil, I dont think its connected with the noise. Anyways this is driving me nuts, I have to listen to music every time I get into my car because i dont want to hear that noise, lol Link to comment Share on other sites More sharing options...
Jaxx Posted September 23, 2008 Report Share Posted September 23, 2008 compressor surge. your CBV is torn. get a replacement CBV or a blanking plate and blow off valve.it has to be the CBV.edit: http://www.youtube.com/watch?v=OuNTnA5A2Fo...feature=related check it. Link to comment Share on other sites More sharing options...
samadkins29 Posted September 23, 2008 Author Report Share Posted September 23, 2008 My 13g was making the same noise, but when I checked the CBV, it was spotless. Everything was perfect on it. Also that vid you linked, is not as close to the sound as the one I linked. I will pull the cbv off my 16t, but I dont think its the bottom cause of the noise. Other notes are both turbos held the exact same psi. Link to comment Share on other sites More sharing options...
Jaxx Posted September 23, 2008 Report Share Posted September 23, 2008 My 13g was making the same noise, but when I checked the CBV, it was spotless. Everything was perfect on it. Also that vid you linked, is not as close to the sound as the one I linked. I will pull the cbv off my 16t, but I dont think its the bottom cause of the noise. Other notes are both turbos held the exact same psi.http://www.youtube.com/watch?v=LZUbo_mNDZM...feature=related it's all the same. smashining between throttle plate and turbo. it can still be a pin-hole that causes the problem. or the cbv isn't sealing correctly. Link to comment Share on other sites More sharing options...
samadkins29 Posted September 23, 2008 Author Report Share Posted September 23, 2008 Also, the noise doesnt happen under psi load, only when I let off the gas thus dropping all psi Link to comment Share on other sites More sharing options...
EricF Posted September 23, 2008 Report Share Posted September 23, 2008 Check the vacuum line going to the CBV.. Link to comment Share on other sites More sharing options...
samadkins29 Posted September 23, 2008 Author Report Share Posted September 23, 2008 Sorry about posting in the wrong section. I will check the cbv. Would a smoke test be able to find that leak? Link to comment Share on other sites More sharing options...
randomdude Posted September 23, 2008 Report Share Posted September 23, 2008 as ericF said, if its not the diaphraghm, its the line that runs to the CBV, i bet money. fo sho. Link to comment Share on other sites More sharing options...
the commissar! Posted September 23, 2008 Report Share Posted September 23, 2008 Mine started that sound immediately after I spiked it up to 18 psi to pass an infinity on the ride in this am...fortunately, I should have a box from UPS on my doorstep when I get home because I knew my CBV was going to go soon w 275000+ on the factory one B) Link to comment Share on other sites More sharing options...
samadkins29 Posted September 23, 2008 Author Report Share Posted September 23, 2008 The only other thing is that it makes the noise even if I am not in boost. I guess ill order the cbv kit. Also hat would I look for on the cbv vac line? Link to comment Share on other sites More sharing options...
Jaxx Posted September 23, 2008 Report Share Posted September 23, 2008 The only other thing is that it makes the noise even if I am not in boost. I guess ill order the cbv kit. Also hat would I look for on the cbv vac line?it doesn't have to be in boost to create pressure to bleed off. my blow off valve would blow enough air to make sound at 10inHg if I let off.first, checked that the CBV line is attached. 2nd, inspect it/replace it. it might have leaks in the line as it's aged over the years. Link to comment Share on other sites More sharing options...
turbor850 Posted September 23, 2008 Report Share Posted September 23, 2008 the manifold has a leak in it Link to comment Share on other sites More sharing options...
randomdude Posted September 23, 2008 Report Share Posted September 23, 2008 manifold what? cbv diaphraghm, or the line connecting it. Link to comment Share on other sites More sharing options...
samadkins29 Posted September 23, 2008 Author Report Share Posted September 23, 2008 my only concern is that I will go and spend $100 on a new cbv, only to find out that that is not the problem. Although 99% of you are saying it is the cbv. How could two turbos be making the exact same noise? With the exact same psi? One turbo had 208K and the other only had 67k. The one with 208k was fine since I bought the car with 204K and for 4k is dint make any noise at all. Not to mention the cbv from the 13g is spotless. I understand that the cbv could very well be the problem, but what are some other things that could cause the noise? I checked the hose to the cbv and it seems fine. Link to comment Share on other sites More sharing options...
lookforjoe Posted September 24, 2008 Report Share Posted September 24, 2008 If you put a vaccum gauge on the CBV & suck it down, it should hold full vaccum for some time; If it does not, it's bad. You may not see a hole in it, since it is layered, it can leak through from one side to the other in a different spot.One way to test this is to remove the CBV assembly, suck it down with vacuum gauge (this will hold the diaphragm against the housing) & dunk the whole thing in a bucket of water. When I did this, I found my leak - visually the diaphragm looked OK.Sounds like compressor surge, which is not a good thing.You can also have an external CBV leak - between the diaphragm & the turbo; with the cbv off, clean the mating surface with scotchpad - in a circular motion. Link to comment Share on other sites More sharing options...
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