Wife and I went to the big city to get a Volvo, bought one today from a used car dealer (I know, I know). It's a '91 740 turbo (not the same one as in my previous posts). On the test drive , I heard a little bit of turbo whine but it wasn't too bad. After my pocket was $3K lighter and I was 10 miles down the freeway, I started to hear a whooshing noise whenever I was into the boost. Any amount of boost would cause this noise and it didn't get louder with more boost, just went away if I backed off into vacuum. Definitely wasn't pinging, just whooshing. Finally, at a stoplight, I put the thing in 1st and went for redline. Turbo really started to act up about 5K rpm. boost would go way into vacuum, back up to mid scale and back and car was bucking at about a 2 second interval, even the shift to second didn't fix it. After a few seconds of this and a big lift on the throttle, it went back to "normal"

I'm going back to the dealer to try to sort things out tomorrow but wanted as much information as possible before returning. I think this is a Mitsubishi turbo, it's a lot smaller than the Garrett on my '82 wagon. Also, the wastegate is way different than on a Garrett and I'm at a loss to figure out how it works. There's a significant amount of oil residue in the intake side and hoses of the turbo as well.

What I'd really like to know is if you think this is a turbo problem, or a wastegate problem, or something else. I checked all the vacuum and pressure lines and can't see any of them split or disconnected.

Thanks for any help on this,
Bob




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82 intercooled turbowagon 235K