Camshaft gone flat

Discussion in 'Mech Tech' started by jim mcglynn, May 13, 2019.

  1. Received this bad news from the garage today. Quite pleased in a way, explains some things. So, new engine, or repair the engine. Thoughts?

    .........
    "Hi, so things are not good with the bus I'm afraid. I've done some checks and found that the camshaft has gone flat, meaning a loss in power and performance, which then leads to over heating due to the engine having far to work much harder to pull itself along."
    ..........

    Thoughts? Anyone got a decent type 4 going spare?

    1979 Super Viking, 2lt type 4, Automatic
     
  2. What makes them/you think its gone flat? Sorry, I am being cynical, I know this is a classic type 4 problem, but what are the symptoms?
     
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  3. They are very trustworthy and reliable, I use them all the time and locally recommended. We've been trying to diagnose an overheating problem. And lack of power. And a bit blowy.

    1979 Super Viking, 2lt type 4, Automatic
     
  4. I haven't experienced this, but I know a man who has, shout up if you need help with symptoms.

    BTW, he went for a Vege recon.
     
    jim mcglynn likes this.
  5. @davidoft has a type 4 engine for sale
     
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  6. Took me ages to work out mine had gone flat. Ask them how they know.
    Get them to drop the oil with you there and remove the plate not just the drain plug. The silvery remnants of the cam will be there if it’s the cam.
    Obviously all bearings will need replacing plus cam followers, oil pump, etc etc
    I did my own and it wasn’t cheap. But less than a new motor.
     
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  7. [​IMG][​IMG]
    This is what the oil looked like and the inside of the case when opened. If the cam has gone flat it will be obvious from the debris left.


    Sent from my iPhone using Tapatalk
     
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  8. Moons

    Moons Moderator

    How come a damaged cam junks the engine....debris alone?
     
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  10. davidoft

    davidoft Sponsor

    It doesn’t necessarily junk the engine, it will probably cause bearing damage and as the case needs to be split it’s sensible to replace them
     
  11. Moons

    Moons Moderator

    So big trouble in little China.
     
    davidoft likes this.
  12. davidoft

    davidoft Sponsor

    Yeah but with less kurt Russell :)
     
  13. I’ve got a rebuild coming up and suspect this will be one of the issues as I get thin silvery flakes of metal in my oil strainer. It probably won’t be me doing it. But what’s the procedure for checking valve lift?
     
  14. With a dial indicator on the pushrod side of the rocker turn the engine over, the difference between the maximum and minimum on the indicator is the cam lift. Multiply by the rocker ratio for valve lift – or put the indicator on the valve side of the rocker.
     
    jim mcglynn likes this.
  15. Many thanks. A new way of looking at my engine, though I don't have a dial gauge. Maybe I can try my electronic calipers.
    Can anything be made of the valve gaps? Generally there's negligible change but if anything one or two will be a tiny bit slacker than before.
     
  16. If you can measure from the valve spring retainer down to the head, valve open and valve closed, then yes your caliper would work. It’s much easier with a dial gauge though – you just watch the dial.

    The valve gap won’t tell you if the cam has gone, or is going flat because the gap is on the heel of the cam and it doesn’t wear because there is a gap (unless it’s a hydraulic cam). The cam nose wears because that is where there is most spring pressure. The lobe lift could reduce down to the base circle and the valve gap would still be perfect.

    Cam profile.gif
     
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  17. That's a great explanation. Thanks.
     
  18. Thanks Geoff. Been chatting to my mechanic about that cam. He says that as I have an Auto, it is feasible that the cam won't suit, due to a shift in the rev range. He's not saying it won't, but might not. Got any thoughts?

    1979 Super Viking, 2lt type 4, Automatic
     
  19. Davidoft.... I hear you might have a T4 engine for sale? Got any detail on it?

    1979 Super Viking, 2lt type 4, Automatic
     
    Last edited: May 14, 2019 at 7:05 PM
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  20. davidoft

    davidoft Sponsor

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