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HELP! 1988 Volvo 740 Turbo Intercooled big (or small) problem. 700

posted by  the real huey on  Mon May 2 15:13 CST 2005
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1988 745 TIC.
Garrett TC

Earlier today i took her out of storage, fired up, changed oil after an hour etc.

Car ran spectauclarly for about 20 minutes, then i stopped for lunch, fueled up and left. About 10 minutes into the ride i left the light, hit the gas and at about 3/4 throttle it hit 3000 rpm and then dropped like i hit a wall. did this several times, went right up on the boost and just as it would normally start pulling hard it would drop @ 3k rpm and then go back.

I stopped at my garage, checked each and every hose/vaccum line and fitting for tightness, all were excellent.

Took off from a light again, this time at 3500 rpm starts making a loud WHOOSHING noise, and the turbo was working (could hear it spooling) just as the turbo would start to make power a loud whoosh (almost like bleeding a compressor tank) would eminate from the pass side (around the turbo area) the boost gauge would just sit at the 12:00 o'clock position with the car sounding like a huge vacuum cleaner, no boost and insane amounts of black smoke from the tailpipe. I ended up going back to my garage and pulled the intercooler completely out to make sure it was fine. (it was) all hoses were fine, and the only notable one i replaced was the small hose from the turbo output to the wastegate.

I asked the question on turbo bricks, i got a few answers, exhaust manifold bolts (they are tight) hoses (yup, they are fine) and the CBV (compressor blowoff valve)

Anyone ever eperience this, the car is literally not driveable. what are the sypmtoms of a bad CBV, and tips tricks hints appreciated!!

Thanks

Chris







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    HELP! 1988 Volvo 740 Turbo Intercooled big (or small) problem. 700

    posted by  the real huey on  Tue May 3 12:08 CST 2005
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    checked it and found it was EXACTLY what you said.

    Thanks for the help, ended up getting the new gasket for the CBV and fixed it!


    Thanks guys, your help has been valuable!


    Chris








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    HELP! 1988 Volvo 740 Turbo Intercooled big (or small) problem. 700

    posted by  fixit2003 on  Tue May 3 06:21 CST 2005
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    If your wife doesn't mind (or know) you can duct tape the family vacuum cleaner pipe to the exhaust and move some burning insense around the suspected leak areas. You may even hear the leak if the vacuums's not too loud but in any case the insense smoke should get sucked into any leaks. Try not to let your neighbors see you doing this.








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    HELP! 1988 Volvo 740 Turbo Intercooled big (or small) problem. 700

    posted by  Steve on  Mon May 2 15:50 CST 2005
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    last visit: Fri Oct 24 07:16 CST 2014
    [RELATED]

    As Randy noted, a blown hose almost for sure. The cracks can be tough to find when not pressurized, but the fact the car was in storage with oil eating away at those hoses is a marker.

    Let us know the solution.








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    HELP! 1988 Volvo 740 Turbo Intercooled big (or small) problem. 700

    posted by  rstarkie on  Mon May 2 15:24 CST 2005
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    last visit: Fri Oct 24 10:14 CST 2014
    [RELATED]

    Sure sounds like a blown hose to me. Sometimes they are difficult to find. I made a plug the size of the hose out of the turbo and installed a Schrader valve in it. I set my compressor for 15 psi and attach the air chuck to the valve and pressurize the system. Very quickly you can find leaks in hoses, fittings and intercooler.

    Randy








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      HELP! 1988 Volvo 740 Turbo Intercooled big (or small) problem. 700

      posted by  Andrew in AL on  Tue May 3 01:52 CST 2005
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      last visit: Fri Oct 24 06:17 CST 2014
      [RELATED]

      The Volvo dealership close to me put my 760 intake system under pressure and found a couple of bad gaskets at the by-pass valve (Garrett turbo). Seems that I have read of folks doing a homegrown version of this if you have trouble finding a leak visually.

      My prob was simular - no black smoke, though. Yours is probably a pretty good sized leak. Mine came down to a bad distributor.
      --
      'Be blessed in your quest'' 89 764 (110K), '94 940T (180K)








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        HELP! 1988 Volvo 740 Turbo Intercooled big (or small) problem. 700

        posted by  the real huey on  Tue May 3 02:16 CST 2005
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        its definetely not a hose.

        I took each and every hose off, (again) cleaned them with simple green, flexed them to check for leaks and nothing.

        I put it back together, pulled the CBV off, checked that, moved with vacuum, seems all is fine.

        went under the hood with the trusty 13mm socket and tightened all the manifold bolts ( or checked for tightness) and found all to be good.

        It seems that the whooshing noise is coming from underneath the turbo. Very loud, and would actually have to get it off the ground to check further.

        So, its looking like its underneath the turbo, would that be wastegate? a gasket in the turbo itself>?

        thanks again for everybodys help, im trying to do this myself (i have a full gargage, but never dealt with turbos before)

        Chris








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          HELP! 1988 Volvo 740 Turbo Intercooled big (or small) problem. 700

          posted by  Andrew in AL on  Tue May 3 03:22 CST 2005
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          last visit: Fri Oct 24 06:17 CST 2014
          [RELATED]

          Back to my fix that was done at the dealer.

          Sounds like you have a Garrett as I do. The CBV valve up by the #1 plug - both gaskets were leaking - so he then replaced both of those. He then adjusted the wastegate. This was a replacement turbo, and apparently was not set up right.

          All this needed to be done - but in the end it was a bad dist.
          --
          'Be blessed in your quest'' 89 764 (110K), '94 940T (180K)







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