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Cam timing after M44 head skim.

Discussion in 'Z3 Roadster & Coupé' started by Barry Gadd, Aug 30, 2014.

  1. Barry Gadd

    Barry Gadd Zorg Addict
    British Zeds The M44 Massive

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    The blown off heater hose during 1st attempt at an MOT plus blown out section of the rad during 2nd attempt have clearly pointed to build up of pressure when the engine got hot.Joey and myself found a really knowledgeable mechanic who rapidly diagnosed this.
    We worked on Joey's car first.His car had exactly the same problem.
    The head was skimmed just under 0.4mm.
    We replaced the head using a standard M44 gasket and used the pukka BMW cam clamp plus flywheel locating pin.
    On start up the engine sounded rough so we got the mechanic to come over and re-set the cam timing after which the engine ran sweet as a nut.
    We've now got my head skimmed with approx 0.45mm removed. and repeated the replacement process also using a standard head gasket.
    On start up the engine also sounded rough. We used the same cam clamp plus pin as before.
    Unfortunately the mechanic has gone on holiday so we are trying to sort out how to adjust the cam timing ourselves.
    Does anyone know how to re-set the timing after removing 0.45mm? (It worked really well with Joey's engine so we know it can be done)
    Facing the cam sprockets do we:-
    Rotate the sprockets clock or anti-clock and by what amount?
    Can we re-set the timing by using the cam shafts clamped or by advancing or retarding should we no longer expect the clamp to fit over the square ends of the camshafts?

    As stated earlier the engine will start but runs rough.

    Any help regarding the above would be much appreciated.
     
  2. t-tony

    t-tony Zorg Expert (I)
    Supporter British Zeds #ZedShed

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    Hi Barry, I'm sorry I can't help but hope you get it sorted soon, before the summer goes for good. It's a bummer really because next week promises to be very nice again.

    Best of luck, Tony.:)
     
  3. zedonist

    zedonist Guest

    Hi Barry, I can't help either, as I would have done the same got my mechanic to adjust the timing, and I would have done the mechanical work. Let's hope he is off Holiday soon.
     
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  4. Barry Gadd

    Barry Gadd Zorg Addict
    British Zeds The M44 Massive

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    Blooming car's driving me nuts.......
    I've done a compression test and found approx 200psi on cylinders 2 , 3 and 4 but zero on 1.
    My compressor is not running properly so can't do a leak down test but nothing seen on the pressure gauge on No. 1.
    I've taken the head off and can't see anything obviously wrong. The head / block and gasket all look as they should. The valves are opening/closing as normal. Combustion chambers 2,3,4 look blackish where they were firing earlier but 1 looks as clean as a whistle ie no compression,no firing.
    I removed the head some weeks ago and noticed corrosion on No. 1 between the cylinder and a water channel where the Ali head was pitted.(There's approx 5mm of Ali here) The engineer who skimmed the head welded this area to make good before skimming.
    I wonder if this welding could have caused the head to crack........ There is nothing visible to show this but it may have happened under the inlet valve head somewhere.
    I have another head that I can get skimmed and start again but any ideas before I go down this route???
     
  5. t-tony

    t-tony Zorg Expert (I)
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    Has to be something quite dramatic to have zero compression Barry. Have you tried putting the pistons half way up/down and filling the bores with paraffin or diesel or maybe even turps as you'll be changing the oil anyway, and see how long it takes to disappear? If the rings are bad on no.1 it should empty quickest. HTH. Tony.
     
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  6. zedonist

    zedonist Guest

    Some of the things my cross flow days:

    Sticking valve (bent, broken spring, etc)
    Valve seats
    Missing spark plug ( bit obvious)
    Broken rings
    Hole in piston
    Cracked head ( think you've ruled this one out)
    Cam timing
     
  7. oldcarman

    oldcarman Zorg Guru (V)
    Supporter Canadian Zeds The M44 Massive

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    Barry, I agree with Tony about checking the rings and piston on # 1 at least. An old friend taught me to plug the spark plug hole with a rag around your air nozzle and inject air into the cylinder at TDC and if you heard air in the oil pan it was rings and if up top then check valves and head for cracks. HTH JIM
     
  8. Barry Gadd

    Barry Gadd Zorg Addict
    British Zeds The M44 Massive

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    Thanks for the replies guys
    I'll try / check your replies quickly.
    The valves open/close ok. The seats look good (I ground each valve in before re-assembly)
    The piston crown looks normal
    The engine was running well with the head I've just taken off (apart from pressure build up when hot) so I very much doubt if anything block / piston related is bad.
    I believe the head may be cracked but I can't see anything visible pointing to this.
    If I get the head pressure tested I'm probably into around £60 for this.
    If I get the head I've just removed skimmed, the cost is £30 and it needs doing anyway so I think I'll go down this route

    Jim the test you described is the leak down test and it's very useful. I wanted to do this but my compressor needs sorting

    I'll get there in the end..........

    Thanks to all.