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  1. barny1

    barny1 New Member

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    Location:
    Herefordshire
    Hi I hope somebody can help!!:cry:

    I have bought a astra (1999) 1.7 tdi with cambelt failure. Its the GM low blow engine, found 2 rockers broken, removed head, valves and pistons ok.

    I have re-assembled the engine with new gaskets etc., but cannot get the crank up on TDC,( also pinned the flywheel) with the exhaust valve camlobe upright, without one of the pistons hitting a valve.

    Please help me, this car has been bought as a non-runner - could it be possible that someone has fitted the wrong camshaft before it came to me???

    Head was removed, all valves were not bent, and lapped backing. nothing protuding the head before fitting.

    thanks in advance

    Barny
  2. Delbert

    Delbert Well-Known Member

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    Location:
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    Rockers broken without damaging a valve or valves?
    If a piston is hitting a valve at TDC it indicates gross mistiming to me. Don't know what the official method is, but what I'd say is rotote the engine in the forward direction until the pistons are at midstroke. Now fit the cylinder head! Note how far the crankshaft timing mark is from the correct position and position the camshaft mark half that distance in the forward direction. You're nearly there and I don't think I need to continue.

    Ill considered rotation of the crankshaft and or camshaft I'd say is bound to lead to tears.
  3. V6Cav

    V6Cav New Member

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    Location:
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    If my memory is correct you need to time the camshaft once the head is on the engine. You need a special tool set that enables you to do this.

    Ive done several on the GM 1.7TD engines myself. Never on an Isuzu engine though...not sure which the low blow is personally.

    But if you removed the camshaft bolt then you should find that there is no woodruff key.

    The idea is to time the bottom end, then time up the cylinder head using the special tool and dial gauge, WITH the cambelt actually fitted... you crack off the camshaft pulley bolt and then rotate the camshaft directly... Its done by angles on the gauge, NOT markings on the top.

    Been awhile since ive done it but i can give a better impression tomorrow if this applies to you?
  4. barny1

    barny1 New Member

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    Hi V6Cav, yes this applies to me the low blow is the GM1.7TD engine (x17DLT). Problem is if I time up and lock the flywheel at TDC, I cannot rotate the camshaft to achieve the lobe position:( (autodata says cylinder 1 at vertical pos.)

    there is definatley no woodruff key on the camshaft.

    i did not drain the tappets before refitting the head and the cams, would this be causing problems??

    any help greatly appreciated M8

    cheers

    Barny
  5. alarmfitter

    alarmfitter New Member

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    you should sqaush the oil from the tappets they maybe pumped up too far
  6. barny1

    barny1 New Member

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    Location:
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    OK guys, I drained the tappets in the vice and set the cambelt timing with a Dti gauge. She starts and runs, but when warm, and bringing up revs, it snaps a rocker/cam follower. Ive done this 4 times now and running out of rockers!! never the same one that breaks - inlet and exhaust - seems like not enough clearance btw pistons and valves - possibly supplied the wrong headgasket?? I replaced the original for the same, but purchased the car with a broken rocker - any ideas chaps??
  7. alarmfitter

    alarmfitter New Member

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    Location:
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    oil pressure releif valve maybe sticking and over pumping the tappets.if you get fed up with it i would buy it for a v6 project.
  8. barny1

    barny1 New Member

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    where is the oil pressure relief valve?
  9. alarmfitter

    alarmfitter New Member

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    on the oil pump
  10. mihaisofti

    mihaisofti New Member

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    Location:
    Suffolk UK
    I have the identical problem on a 1997 astra with low blow GM engine. What is the special tool, and what does it comprise?
    TIA

    Mike

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