Date: 1 Dec 2002 19:44:31 GMT
Subject: Re: opening turbo

Someone who looks an awful lot like Dave G <nospamnopsamom> wrote: > Jeez-I do apologise-1986 900 2.0 16vTurbo-sorry. > Thanks again. Were you here a while ago? I remember someone asking about this, where the dealer had turned down the turbo to compensate for a slipping clutch, was that you? In any case, the wastegate adjustment is most likely what they messed with. Find a nice stretch of road, get to maximum boost, see where that is on the turbo gauge. What you want to do, is change the length of the rod between the wastegate itself (on the "hot side" of the turbo) and the device which opens and closes it. Hang on a second, let me go find something... OK, I'm back... I'm looking at the Saab service manual, section 291, regarding "Adjusting the charging pressure regulator (waste-gate valve) as from 1982 models with APC". I'll paraphrase rather than type the whole thing... First, a warning, the rod from the diaphragm to the wastegate must not rotate relative to that diaphragm. You need to turn the end on the rod, which means you need to disconnect it from the turbo. If you turn the rod, you'll rip the actuator diaphragm, which would be a bad thing. So. Disconnect the rod from the wastegate. The wastegate should be in the "closed" position when the car isn't running, remember which way the control arm'll need to know that. While you have the rod disconnected from the turbo, feel how the actuator is. Should have a definate point where it wants to be, if it's wiggling around like a loose tooth, it's probably not good. Specifically, if you pull or push on the rod, it should return to about the same place. Now, find your starting point. Back off that jam-nut that is on the shaft, holding the end piece on that rod from rotating. Back it off a bit so you can turn the endpiece. Turn the endpiece on the rod until the length is right on, so you can put it onto the wastegate control without stretching or pushing on the diaphragm. That's your zero setting, where we'll start from. Screw then endpiece inwards (tighten on the threads of the rod) 3 and 1/2 turns, and tighten up the jam-nut you loosened earlier. I bet you'll see a clean spot that lines up with what you just set it to... Put the endpiece back on the control of the wastegate, and secure it with whatever you took off. A piece of safety wire (...or equivalent...) will work where the lead seal was when it left the factory. That will get you to the base boost setting, give or take a bit. If you have a boost gage with numbers on it, you can set it more precisely, but I don't have that spec in front of me - 0.35 bar, maybe? In any case, this will get you close, and probably much closer than you are right now. Dave Hinz

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