Engine troubles

Discussion in 'Motorhome Chat' started by topman, Jan 24, 2010.

  1. topman

    topman

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    Hi all, I have been having problems with a misfire on my 1988 2.5 diesel Ducato following a head replacement, as soon as the glow plug timer cuts off it has a permanent misfire on cylinder 2, I removed the head again today but i can find no signs of valve problems or cracks. Has anyone had a similar problem or any advice:Sad:
     
  2. ourcampersbeentrashed

    ourcampersbeentrashed Funster

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    if you let funsters know where you are some one nearby may be able to help
     
  3. pappajohn

    pappajohn Funster Life Member

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    welcome to the fun topman.....

    sounds like a dirty/faulty injector to me.
    may be worth having them all overhauled.
     
  4. John H

    John H

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    Can you swap over the injector to isolate the problem ?
     
  5. topman

    topman

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    I changed the injectors but it made no difference:Sad:
     
  6. Jaws

    Jaws Funster Life Member

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    Could well be the pump its self.
    By the sound of it you know your way round an engine but do you know how to ( quick and dirty method ! ) check the spray pattern from an injector ? I know you have swapped em and eliminated the injector its self but if the pump is misbehaving it will still show up..
     
  7. olley

    olley Funster

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    Hi you need to do a compression test, all cylinders should read similar, you can hire one from the hire shops.

    Olley
     
  8. pappajohn

    pappajohn Funster Life Member

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    what was the reason for the head change ?

    did you have the replacement head skimmed and high pressure crack/leak tested ?
    how have you accertained its No 2 cylinder ?
     
    Last edited: Jan 24, 2010
  9. topman

    topman

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    The head was changed following an exhaust stud snapping, I managed to purchase a head that had been completely reconditioned with new valves/shims skimmed and tested for cracks but following the transplant I have had nothing but problems. I have changed the injectors, changed the fuel filter, bled the fuel system checking each pipe for supply to individual cylinders. I have exhaust gases blowing back through the inlet manifold and a distinct misfire. When I dismantled last time to investigate I found soot around the inlet manifold to no2 cylinder.
     
  10. chesterfield hooligan

    chesterfield hooligan Funster

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    :Smile: Still not said where you are :Smile:
    Brian and Marion
     
  11. John H

    John H

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    It sounds like a sticky or bent inlet valve to me.the valve must be staying open when the engine fires to make the inlet manifold sooty, have you tested the valve opening/closing with the head on? it could be a cam timing problem.
     
  12. Jaws

    Jaws Funster Life Member

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    Now then !!!

    This is a real shot in the dark and I aint seen it since.. well for a LOOOONG time

    When you fitted the inlet and exhaust manifolds are you 100% certain the gaskets were lined up spot on ? In other words, if the old head had locator spacers and the new one didn't, it is possible the gasket to drop a little.

    We struggled for a week or more with a Princess ( an old Hearse actually ! ) and in the end called in an Austin man

    Told the story and he jumped on it straight away

    What i STILL do not understand is that if it was out of line ( and we are talking about only an 1/8" or so ) on cylinder number 3, it MUST have been out of line for the rest as well, yet it was only the third pot that constantly failed to fire !


    But !!! Yes,, more likely to be a bent or sticky inlet valve ..
     
  13. topman

    topman

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    Would a bent or sticky valve run ok when starting from cold, the misfire starts as soon as the glowplugs stop. I have removed the head once already to investigate this but ruled it out, I tried altering the cam timing slightly and the pump timing slightly but both made no difference.
     
  14. pappajohn

    pappajohn Funster Life Member

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    ifn you end up taking the head off again try this.....

    ensure the valve heads and seats are dry and No 2 valves are fully closed, support the head, right way up, off the bench and squirt WD40 into the inlet and exhaust ports.....put plenty in so covering the valve heads fully.
    leave for an hour or two then check around the valve heads for damp/wetness.
    if there is you have a bent valve but to such a small degree you wouldnt normally see it.
    dont forget the cylinder pressure is enormous....upwards of 20 to 1 compression ratio so the smallest of gaps will allow loss of compression.
     
  15. topman

    topman

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    I took the head off again this afternoon, I have tried it the other way around spraying wd40 around the valves with the head upside down and all seemed fine but I will give it a go to see what happens. I think there will soon be a shortage of head gaskets in Essex if I dont get it sorted.:Doh:
     
  16. pappajohn

    pappajohn Funster Life Member

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    just had a thought on head gaskets.

    are you using the 'conversion' gasket.

    if the heads been skimmed it will need a slightly thicker gasket, which corresponds to the amount of metal removed while skimming.

    the valve heads run so close to the piston crown, using a standard gasket it could allow the valves to just touch the pistons and bend them.

    you obviously know your engines so i dont really doubt you know this already but worth a mention anyway.
     
  17. John H

    John H

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    It may run ok when cold, then as the engine warms up the additional heat may be enough to alter the bent valve and cause your misfire. as mentioned before a compression tester is the easy test and you dont have to take the head off.

    John
     
  18. Larrynwin

    Larrynwin Funster

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    Heat from the glowplugs aid combustion so no misfire, as soon as the heat is gone only compression is left to fire, sounds like inlet valve problem, bent or not seating clean. Compression test will find it.
     
  19. metalmickey

    metalmickey

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    you said that it has been shimed is there enough clearance for the valve to close.
     
  20. topman

    topman

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    When the valves are closed to each cylinder you can rotate the cam followers freely underneath the shaft
     
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