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Most baffling problem EVER! 700 1989

posted by  Brick Skinner on  Tue Apr 15 19:04 CST 2014
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last visit: Fri Jun 13 13:31 CST 2014
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...for me at least. Read on.

My 740 turbo quit on me just as I arrived in the driveway yesterday. What a huge blessing that it didn't break down anywhere else!

Today, I got to poke around under the hood and here is what I found:
- zero compression on all cylinders
- cranking is strong but no ignition
- timing marks all right on
- timing belt in perfect shape and tight
- spark good
- fuel pressure good
- no sign of head gasket damage
- coolant is clean
- crankshaft pulley good and pistons all move, no slippage on pulley
- cam shaft turns with gear
- gas in the tank
- oil is dirty and needs to be changed

The missus has been nagging me to get rid of the brick for a pickup. Is it time?
--
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    Most baffling problem EVER! 700 1989

    posted by  pageda on  Wed Apr 16 04:22 CST 2014
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    last visit: Fri Oct 24 13:18 CST 2014
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    The alignment tab on the crankshaft sprocket / gear has likely sheared off and the engine is not timed. Put the crankshaft on TDC of the compression stroke and look to see if both #1 valves are closed, they should be.
    Dan







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      Most baffling problem EVER! 700 1989

      posted by  Brick Skinner on  Wed Apr 16 09:19 CST 2014
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      last visit: Fri Jun 13 13:31 CST 2014
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      When I peer into the valve cover while at TDC, I see that the front-most cam is about to contact the valve. The second cam back is at about 90° from the front one and on the way down also. So, I don't know where the cams should actually be oriented while at TDC. But I can say that the way mine looks at TDC is the same as shown in this picture...
      http://www.ipdusa.com/uploads/images_products_slideshow/fullsize_7761.jpg
      ...cam lobes oriented about the same. In other words, if you put the cam in this picture directly into my car at exactly the same rotational position it would be at TDC.
      --
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        Most baffling problem EVER! 700 1989

        uid 18083's pic
        posted by  lucid on  Wed Apr 16 09:43 CST 2014
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        last visit: Fri Oct 24 12:31 CST 2014
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        "So, I don't know where the cams should actually be oriented while at TDC."

        I think your picture shows lobes 7 and 8 closest. When the crankshaft is at TDC for #1 cylinder, cam lobes 1 and 2 should be as shown below.
        Number 1 pointing inboard/left and lobe up about 25°
        Number 2 pointing horizontally w/lobe outboard/right





        --
        Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.








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          Most baffling problem EVER! 700 1989

          posted by  Volvo From Heck on  Wed Apr 16 10:12 CST 2014
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          last visit: Mon Oct 13 20:56 CST 2014
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          I think it should be added for clarity -- when the crankshaft mark is at 0 degrees it is at TDC for both #1 and #4 cylinders -- just on different strokes for each. The way the original poster describes it it sounds like his motor is on TDC compression stroke for #4 -- or at least close to that. He needs to rotate the crank another 360 degrees to be able to see the cam for #1 on the compression stroke.-- Dave








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    Most baffling problem EVER! 700 1989

    uid 1848's pic
    posted by  vigilante on  Tue Apr 15 23:07 CST 2014
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    last visit: Wed May 28 21:16 CST 2014
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    Your symptoms sound more like a broken drive cog on the crankshaft timing pulley.
    Did you look in through the oil filler to see if the cam was turning when the engine was cranked? Being a non-interference engine, valves will not hit with a with clank yet if cam is not turning, there will be no compression. Second choice would be sheared pin on the cam drive sprocket.








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    Most baffling problem EVER! 700 1989

    posted by  james_a_sousa on  Tue Apr 15 19:36 CST 2014
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    last visit: Thu Oct 23 18:51 CST 2014
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    Did you try oil in the cylinders, to check rings?

    Better yet, did you prove your compression gauge by trying it on another engine?

    No compression sounds very fishy.

    Bad test equipment can be the worst breakdown of all.








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      Most baffling problem EVER! 700 1989

      posted by  Brick Skinner on  Tue Apr 15 20:22 CST 2014
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      last visit: Fri Jun 13 13:31 CST 2014
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      I hear what you say. The compression gauge works cuz I tried it on my boat motor. Before I try oil in the cylinders, I'm gonna remove the cam shaft gear and inspect that. Can't do it any more this eve though.
      --
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        Most baffling problem EVER! 700 1989

        posted by  Nahtanha on  Wed Apr 16 12:22 CST 2014
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        last visit: Tue May 20 10:10 CST 2014
        [RELATED]

        Is your harmonic balancer pulley separated? see if the belt lower drive cogg for the belt is moving . Sound too much like the something slip and out of sync. Being a non interference engine , you can crank forever. Think simple, because hard thinking is not working.







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