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Re: Turbo going bad? Posted by RS [Email] (#15) [Profile/Gallery] (more from RS) on Thu, 7 Jun 2001 12:58:38 In Reply to: Turbo going bad?, DaleG, Thu, 7 Jun 2001 11:06:13 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Well, the AIC (Automatic Idle Control) valve and the hooter valve (Turbo Bypass Valve) are two completely different things, so I think that you were given a bit of an unintentional red herring.
If what you are hearing is a very high pitched whistle that varies with the amount of pedal you're giving it as you accelerate, then you are indeed hearing the turbo spool up. If not, then you're hearing something else.
Assuming that you are hearing the turbo spooling up and it's much louder than usual, there are a few things I've experienced that it could be:
- The connection from the turbo discharge elbow to the downpipe is loose. Tighten the flange bolts.
- There is a weld on the downpipe that runs the length of the downpipe that has deteriorated and it's letting exhaust and noise escape. (The downpipe is essentially a long sheet of steel that is rolled and welded to make a tube. The weld sometimes rusts away.) Replace the downpipe. I had to do this a month ago on my '89 SPG.
- The connection between the downpipe and the converter is loose. Tighten the flange bolts.
- The downpipe walls have thinned to the point that the turbo whistle isn't dampened. Replace the downpipe.
If the noise was coming from the compressor side of the turbo because of openings in the induction system, you'd have driability problems in addition to the noise.
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