APC/Turbo needle movements? [Archive] - SaabCentral Forums

: APC/Turbo needle movements?

24th September 2002, 01:41 AM
Hey All, I know, my questions may seem amateurish to you, but bear with me, I've never had a decent car like this (though if you saw the outside, you would all agree I probably got soaked for the car), in regards to the APC/Turbo Gauge on my 86 9000 turbo has 3 "areas" on it, as I am sure most of you are aware :p but the boost needle never goes in to the lowest one, the green one, it always stays in the white/orange, and on the hardest acceleration gets maybe up to the 1/3 point of the white/orange area, never touching the red.... any ideas? I am wondering if it is a cracked or split hose, but I am not sure as of yet. Any ideas appreciated.

24th September 2002, 02:38 AM
The clue is that the gauge never goes in the green. Even if you were getting no boost at all, you should be getting vacuum with your foot off the accelerator, so the gauge is lying. Now, I'm hoping this goes for the '86, as I've only looked at later ones, but there is a rubber vacuum hose going to the gauge and it comes out through the firewall into the engine compartment near the brake master cylinder where it goes to a "Y-piece". One hose then goes off to the plenum chamber (that big aluminium tank that runs across the inlet manifold) and the other goes to the black plastic bypass valve that I think on the '86 is tucked down by the turbo. One or all of these hoses are cracked, split or disconnected. I'd replace them all if you can get about 10' of hose (maybe a few feet more if you need to go into the dash to replace the one going to the boost gauge). I think it's about 1/4", but I just took a piece to a local car parts shop (the type of place that will sell you a single washer or bolt, without you having to pay a fortune for an overpriced blister pack of 5) and asked for more of the same.

And most of our questions here are amateurish, as there are only a couple of professionals here. If everyone felt self-conscious about asking questions, we'd get nowhere. To put your mind at ease, the 9000 (and other Saabs) are put together in quite an unusual way so some of their problems do tend to seem a bit odd. Especially compared to "Detroit Iron", it seems to appear rather alien.

24th September 2002, 02:56 AM
sounds like a weekend job to me when I get to montana and get the time and money to do it....
I kind of figured that would be the case (referring back to your original reply on this Bill), going to have to trace the hose and check it out first.... with other hoses coming up disconnected on my car, I wouldn't be surprised to find one of those hoses disconnected too.
I am going to check them out tomorrow morning while I wait for the phone to ring, literally. Now tell me this, do you think I got soaked? I spent about $2600.00 on this car, 128K miles on it, body is beat to hell, but with a little work, it's running great, no major problems thus far and none in the future so far as the shop guys told me. I also need a brake job in this car, because the master cylinder has been recently replaced (another repair racked up), but it still is leaking brake fluid somewhere and the brakes are still rather spongy, though they remain firm for a couple of days after I bleed the system, air eventually gets in and I lose fluid. The interior is shredded and in general needs a lot of work, but I figure for the engine running as well as it does, I don't think I got soaked too badly.... talk to ya later.

25th September 2002, 06:54 PM
Looks like it is going to be a replacement of the hoses, I just checked all of the hoses, even going so far as to trace their path, check their connections and check the hoses for any sign of cracking or of some other form of a hole, but I could find nothing what-so-ever visible. And it looks like they have been replaced already before, unless factory stock for the tubing is blue, which has me worried it may be something a little more serious, such as a replacement of the turbo or one of the parts therein. Question is though, does the Haynes manual happen to have an diagrams on this part of the car? For all I really know, I may have checked the wrong hoses, but I think I had the right one, it came out from behind the driver's side dash, has a Y connector on it, and splits in to two places, is it the right one? or maybe am I chasing pipe-dreams, so to speak? Any input welcome at this point before I actually have to put it up on a rack in montana and go digging around. Hope to hear something soon.

26th September 2002, 07:39 AM
The blue stuff is not factory-fit. Sounds like you have silicone hoses which are quite expensive and last well. Make sure they are sealing correctly everywhere they are fitted, though, because if someone bought the wrong size, they could leak. Those are the right hoses you're looking at.

Don't worry about the turbo yet. A dead turbo will not cause the gauge not to show vacuum. The only thing that I can think of that will cause this and still let the engine run is a bad vacuum connection (or a faulty gauge, but I've never heard of that happening). Haynes doesn't have a vacuum diagram, as far as I know, but what you describe is just about all that should be in the engine compartment, although I stand to be corrected as I've never looked closely at an '86.

Did we establish that the bypass valve (dump valve) works? A split diaphragm in that could represent a substantial vacuum leak.

What about the hose after it goes into the dashboard on your driver's side (my passenger side here in the UK)? Since that's a bit harder to get to and the hose in there is not likely to deteriorate so quickly, being inside the car, perhaps it's still original and now needs replacing. Unfortunately, checking this involves taking the dash top off, which isn't a big job, but takes a little while.

Oh, and sorry, but I'll have to let one of your countrymen answer about the price, as I don't know much about the US market for secondhand Saabs.