Date: 14 Dec 2004 15:05:13 GMT
From: Dave Hinz <>
Subject: Re: 99 Turbo update - vroom vroom

On Tue, 14 Dec 2004 09:54:32 +0100, Frode <> wrote: > Dave Hinz wrote: > >> Ah. I have no exhaust system on the car right now aside from the >> header, and that has leaks. > Must sound interresting, Should give you more high-end boost than most 99's, > but I don't think that is the source of your problem. Agreed. >> How do I check the wastegate with a bicycle pump, please? > Locate the tube going from the exhaust manifold near where the tranny > dipstick is located to the aluminium top cover of the regulator housing. > Disconnect it at the top cover, careful with the threads at the manifold > side, they are likely to be rusted and brittle. Right, I see them (in my photos; I'm not near the car right now). > Now you can verify that the diaphragm is intact by gently applying > compressed air onto the housing. There should not be significant leaks, as > that would flood the regulator with hot exhaust all the time, no doubt with > harmful results, Ah, so this is how it measures the boost pressure, through that line. Pushes down on the diaphragm to open the bypass valve, yes? An elegant solution. > I am not sure how much pressure is needed to crack open > the valve, especially not one that has been sitting for a decade, That's what I'm thinking. From the diagrams from my 79-80 c900 manuals, which should be the same enough for these purposes (yes?), it looks like, well, a valve valve. Could be stuck to the seat, could be stuck along the stem. Probably want to take the top off as you mention just to check that, being that head gaskets aren't cheap and all. > Don't rotate it as that would destroy the expensive > rubber-diaphragm instantly! Check that it can be pushed in and that it > comes out again by itself. Will do. I have at least 3 spares, but I'd rather not start breaking things anyway. > BTW, the big, locked nut at the end of the shaft is of course the place to > adjust the boost. Increased spring pretension results in more boost. > You may want to go the other way at first. That will exersize the wastegate > system a bit extra too. So if I turn down the boost until I get a feel for everything, that'll make it travel more and un-sticky itself, in thory at least. Sounds reasonable. There'll be more updates, oh yes, I guarantee it. Dave Hinz

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