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Questionable compression test results?

Discussion in 'Vintage (thru 365 GTC4)' started by mdw3, Jan 2, 2005.

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  1. mdw3

    mdw3 Karting

    Jan 2, 2005
    194
    Los Angeles, CA
    Full Name:
    Michael
    #1 mdw3, Jan 2, 2005
    I have been in discussions regarding a potential purchase of a '66 330 GT 2+2, Series II, car, and have now received the results of a recently performed compession test. Apparently, 11 of 12 cylinders performed similarly well, at about 150 psi, while the 12th was way down, well below 100. I realize the cause may be worn ring, warped head, bad valves/springs, etc., but, in any case, am I correct in my assumption that the only true remedy will be a total and complete rebuild? Should I run for the hills on this one? Thanks in advance!

    Michael
     
  2. Bryan

    Bryan Formula 3

    Nov 1, 2003
    1,310
    Montrose, Colorado
    #2 Bryan, Jan 2, 2005
    A leakdown test will shed additional light on the potential sources of the compression loss and provide better data than a compression test on repair costs.
     
  3. robsandiego

    robsandiego Rookie

    Jan 10, 2004
    43
    San Diego
    Full Name:
    Rob
    #3 robsandiego, Jan 2, 2005
    Search the Vin # and I bet you'll find that car already PPI'd and talked about here...
     
  4. tbakowsky

    tbakowsky F1 World Champ
    Consultant Professional Ferrari Technician

    Sep 18, 2002
    19,875
    The Cold North
    Full Name:
    Tom
    #4 tbakowsky, Jan 2, 2005
    It does not nessarly mean you need to rip the thing apart and spend 20k to fix it. Now that you have done you compression check it's time to carry out other tests to find out were the cylinder pressure is leaking.

    First thing I would do..Reach for the leakdown tester. This test will tell were you are losing the cylinder pressure. It will tell you if it's rings or valves. If it turns out to be valves..then you may just get away with a top end repair. Repair the problem with the head and slap it back together until next time. If it turns out to be rings..well then yea your in for a rebuild.

    Of course have all this checked BEFORE you spend the money for the car. But hey..even if it fails the test..all it will need is some money and all will be good again.
     
  5. mdw3

    mdw3 Karting

    Jan 2, 2005
    194
    Los Angeles, CA
    Full Name:
    Michael
    #5 mdw3, Jan 2, 2005
    Thanks for the responses so far. I realize that further analysis should be done to determine the cause and severity of the leaking, but one thing I am sure of is that I am not up for purchasing an old car in immediate need of major engine attention (particularly a Ferrari). I'm sure this car has never been discussed here--it is a car that is, and has been, with a private party and not even officially for sale. This is the first full inspection the car has had in years. And it runs really, truly well, always fires right up, never left its owner stranded, no leaks on the garage floor, no smoking. That's why I had such high hopes for it, initially.

    Michael
     
  6. ferrarifixer

    ferrarifixer F1 Veteran
    BANNED

    Jul 22, 2003
    8,520
    Melbourne
    Full Name:
    Phil Hughes
    #6 ferrarifixer, Jan 3, 2005
    The carbed 12's are a dirty old bunch, If the car has been sitting around for a while, it should have a good drive for at least 30 minutes, but more if possible to try to clear things out.

    Repeat the compression test, then do a leakage test after that to get a better idea of how things are.

    Stored cars often get sticky rings that loosen with use, I'd not be too worried yet until you know for sure it's recent history.
     

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