Need help diagnosing 3b problem.

Discussion in 'Diesel Tech / 24 volts' started by Ron_85BJ60, Jun 23, 2005.

  1. Ron_85BJ60

    Ron_85BJ60 SILVER Star

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    My 85 BJ60 has been shutting down a bit rough lately and has gotten bad enough that the guy that put my new exhaust on was concerned that I had a bad motor mount. He was concerned that the new exhaust would be damaged. I checked it out and got a couple of other opinions and we settled on it needing a new motor mount on the fromt right side.

    The new mount was installed today and it did not solve the problem. I know little to nothing about deisels so I need some advice. Do you think it could be something with the motor or should I just bite the bullet and replace the mount on the other side? I dont want to spend another $140 for nothing and I'm really not convinced that it will help. The rear mount seems fine and the one that was removed didn't show any clear sign of failure. Took the other side mount of also and again don't see any visual signs of damage/wear.

    When I shut the truck down it makes a pretty loud thunk and there seems to bit too much sideways torquing going on. Does pretty much the same thing when I start the truck but not as bad of a movement. Help!

    Ron
     
  2. Jan-78FJ40

    Jan-78FJ40

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    Have you checked the entire length of the exhaust for play or loose bolts?
    I am asking because I had a smililar sound very recently, and trying to diagnose it alone made me think it came from the right side of the engine.

    after a few shut-down cycles with a friend under the truck, we localized a broken exhaust hanger bolt right under the passenger door, which made the clunk when shutting down. also the exhaust-manifold connection missed a washer, and one was loose.
    maybe it is as simple as that.

    IMHO, a broken engine mount should result in serious vibrations, and the truck should slip out of gear.
    j
     
  3. silvercrusher

    silvercrusher

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    Did you have the flexible coupling before the new exhaust was put on and perhaps now it is missing?
    It is located right after the manifold and takes up alot of vibration down the line. Yours should have one since it is an 85.
     
  4. mac

    mac Crew Member

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    Is your primer pump leaking onto your driver's side engine mount? This will deteriorate the rubber portion of the mount and can cause the symptoms you describe.

    Mac
     
  5. Island Moose

    Island Moose

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    A clunk is metal on metal, you may be missing the braided steel flex-joint.

    Did it clunk before the new exhaust?
     
  6. Ron_85BJ60

    Ron_85BJ60 SILVER Star

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    No braided coupling or flexible joint and I don't think there was one prior to the new exhaust. It's a 2/85 so maybe it didn't have it? If someone could post a picture I could tell for sure.

    The primer pump is not leaking on the mount and I had the mount off earlier today and it looked OK.

    Yes, it was clunking at shut off prior to the new exhaust which I thought was being caused by too much movement of the motor, hence the new motor mount.

    I just noticed a tinking/pinging sound coming from the exhaust so maybe it is loose somewhere. I checked and the is no contact with the frame or anything. The hangers all seem to be welded tight to the exhaust. The exhaust does run very close to the frame where it drops down from the manifold but there doesn't seem to be any actual contact with the truck even when running. Possibly lose at the manifold? It doesn't look to be but I can try tightening. I really don't think the new exhaust is the cause of the original issue. The motor just seems to lurch too much at startup/shutdonw to be normal.

    The new mount does seem to be holding tighter than the old one but I'm still not convinced it is the problem. Do the mounts get sloppy over time? Any one experience any issues with original mounts?
    Thanks for your replies.
    Ron
     
  7. Island Moose

    Island Moose

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    The flexible length of exhaust hose is, as I understand it, really necessary, especially for start-up and shut down, when the engine shudders significantly. It is supposed to isolate the movement of the engine from the exhaust system, otherwise the shudder gets sent all the way down the line.

    Have your exhaust guy plumb in 8-10 inches of flex-hose at the point where the exhaust clears the firewall and goes horizontal.

    In terms of what's a "normal" shudder at shut-down?...that's a tough one, I would think that would differ even between similar trucks.
     
  8. fjbj40

    fjbj40

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    yup ...that flex coupling is your culprit...mine use to be like that...when new exhaust with flex coupling was installed away went the clunk .
    Daryl
     
  9. Island Moose

    Island Moose

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    And FWIW, your exhaust guy should have known this, he cost you the price of an uneeded engine mount.
     
  10. silvercrusher

    silvercrusher

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    As far ar i remember that flex piece is 84 and after. It should have been there. If you don't have it chances are you wil start to loosen and then break the studs on your exhaust manifold. Get your wife or someone to start the truck and watch the pipe where it bends after the manifold you will be amazed how much it moves.
     
  11. Ron_85BJ60

    Ron_85BJ60 SILVER Star

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    Thanks guys, looks like I need to call the exhaust shop. By the way I'm in the US in Ohio, do you still think this is something he should have known about? He's probably never seen a deisel Land Cruiser before. I'm just wondering how much heck to raise when I speak with him.
     
  12. tlcruiserman

    tlcruiserman SILVER Star

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    Someone recently told me that the flex pipe exhausts are illegal in USA. I am not sure if that is a state by state thing (probably) or a federal thing. If it is state by state I think it was illegal in California. Your exhaust shop guy should now for sure.

    Cheers,

    Michael
     
  13. silvercrusher

    silvercrusher

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    I think if you look around most diesel engines have these pieces on the exhausts just from the inherent nature of the starts and torque that develops. You may have other issues also like a crappy injector. If one cylinder is getting raw unatomized fuel it will take longer to flash then the others causing some noise until it heats up sufficiently. You may also want to look at your glow plugs and ensure they all work. But judging by the shutdown clunk i think its the flex piece. Mr Toyota doesn't usually make mistakes!!
     
  14. brisveganbj42

    brisveganbj42

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    ive had the same thing since ive had my bj42.. its got an 06/84 3b and I'm about 100% sure its still got the stock exhaust. Nowhere on there is a flexi joint..

    although i will need to make sure by checking it out but it makes sense.. Its also interesting hearing about the potential for exhaust manifold stud failure as i think i ve got some exhaust in the cabin from a leaky gasket.. could it all be related?

    anyway.. thanks for the heads up..
     
  15. silvercrusher

    silvercrusher

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    There definatley could be a problem there. If you think about it when you crank the engine over it pretty much stands on the studs without that flex piece . Those studs arent designed to take that shear stress so they will fail. I believe that is why later models got the flex joint. :beer:
     
  16. lowenbrau

    lowenbrau

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    Anybody got a PN for the factory flex pipe? I just parted an '85 BJ60 that didn't have one, and neither my '86 HJ60 or '86 BJ70 have them and, frankly, I've never seen one that wasn't aftermarket. I think its a good idea but I'm surprised to hear it is factory. Back to the original question, it sounds like motor mounts to me, don't forget the tranny one.

    Finally, if you don't have a flex pipe there should be a place to clamp the downpipe to the bell housing about 12" below the manifold. It is very important to have this clamp or the pipe will break near the manifold.
     
  17. silvercrusher

    silvercrusher

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    I think wayne may have it. I remember a previous thread about this some time ago.
     
  18. crushers

    crushers post ho

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    all the LJs i have seen have them.
    but most exhaust systems i have seen do not have the flex.
     
  19. folsom50

    folsom50

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    Maybe they where talking about a full flex-pipe exhaust on a passenger car, and that I can't say for sure. But every semi I've every drove had a flex pipe exhaust just before the "stack"
     
  20. 1FE pig

    1FE pig

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    Flex pipe is a dirty word,stainless exhaust flex coupler.Most all front drivers have them because of torq on the pipe.Walker makes aftermarket ones.Can't tell you if it was factory on a BJ ,but it was on a tercell.I use them when i modify the headpipe to cut the vibration.
     
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