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Indy 4900 Head gasket problem

Discussion in 'Maserati' started by Bisgaard, Oct 28, 2019.

  1. Bisgaard

    Bisgaard Rookie

    Feb 14, 2015
    22
    Denmark
    Full Name:
    Oluf Bisgaard
    #1 Bisgaard, Oct 28, 2019
    Hi guys
    A couple of weeks ago, my Indy 4900 suddently emptied the cooling water out through the exhaust. A bad day at the office...
    I hope it is "only" a blown head gasket and not the cylinder head itself. What is Your experience with a situation like this? Is the heads a weak thing, or is there a chance that it is only the gaskets?
    I took of the valve covers. The cam shafts looks fine.
    But how do I take off the heads? As far as I understand, there is a chain for each side and a central chain from the crank to each side.
    Is there a smart way to open the engine without taking off the chains on the cams?

    Thanks in advance, guys.

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  2. thecarnut

    thecarnut F1 Rookie
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    Apr 22, 2006
    2,528
    Atlanta
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    The Car Nut
    #2 thecarnut, Oct 28, 2019
    Have you done a compression test to see if one or several cylinders are very low? Start with the easy stuff first, which is to re-torque both heads to specs. If you find several bolts were very loose this might (although most likely not) fix the problem. If that does not fix it then you need to figure out which head failed. Did coolant get into the combustion chamber? You can normally tell since that spark plug will be very clean.
    Disconnect where the exhaust pipes connect to the exhaust manifolds and look for signs of coolant, this should tell you which head failed.
    The chain for that head will need to be disconnected in order to remove the head. Anytime you disconnect a chain you need to be extremely careful to keep proper timing. I use yellow paint and mark everything (distributor position, intake and exhaust cam positions, crank position, chain linkage relative to the cam sprocket, etc)

    Ivan
     
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  3. Bisgaard

    Bisgaard Rookie

    Feb 14, 2015
    22
    Denmark
    Full Name:
    Oluf Bisgaard
    #3 Bisgaard, Oct 28, 2019
    Hi Ivan, thanks a lot for Your reply :)
    Yes, I got coolant in one of the chambers on the right side (#2 from the cabin), a lot. It also went out through the exhaust.
    A year ago, I removed the original water pump (and AC) and replaced it with an electric pump. That gave me high flow with low RPM, and it solved the heating problems i had for years. So of course I have higher pressure on the coolant, but I would say no more than original water pump on high RPM. Anyway, it should not be able to damage a head gasket.
    So I see no other way than opening the engine.
    Would You say, that I should take out the engine, or is it possible to do this operation in the car?
    In order to it, I guess I must remove all pulleys and take of the cover behind it. Can I see the chain wheel then? I have seen all the fine drawings from the Eurospares homepage, but it is dificult to see how to disassemble it.
    I have opened other engines before, but never with OHC.

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  4. thecarnut

    thecarnut F1 Rookie
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    Apr 22, 2006
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    #4 thecarnut, Oct 28, 2019
    Head should clear without having to remove the engine.

    Rotate the engine to TDC on the flywheel and look for the chain link. If you do not see it, rotate the engine 180 degrees. Once on TDC and the chain link is in a position that it can be removed, mark everything and take good photos. Loosen the chain tensioner, remove the link and make sure both ends of the chain are held with a string or wire so that it does not fall inside the engine or loose its position on the lower sprocket. I like to loosen the cam bearings so that all the valves are closed before removing a head. That way there is less risk of bumping a valve that is open. Remove the head bolts in the order shown in the QP3 repair manual. http://thecarnut.com/Manuals/QP3_service_manual_engine.pdf

    Ivan
     
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  5. Bisgaard

    Bisgaard Rookie

    Feb 14, 2015
    22
    Denmark
    Full Name:
    Oluf Bisgaard
    #5 Bisgaard, Oct 28, 2019
    Thanks a lot for Your answer and advices.
    It must be possible to do it with the engine still in the car.
    Now, I feel ready to do the job. I am very exiting to see if it is only the gaskets, or if the heads is damaged.
    The QP3 manual gives also a lot of answers on my concerns.

    Best regards Oluf Bisgaard
     

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