Compression Test Results 400i | FerrariChat

Compression Test Results 400i

Discussion in '365 GT4 2+2/400/412' started by Fort Worth 360, Nov 30, 2020.

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  1. Fort Worth 360

    Fort Worth 360 Formula Junior

    Jan 3, 2008
    409
    Fort worth Texas
    I am curious what other think about what the acceptable range of values is when performing a compression test.

    A rent car I asked to be evaluated returned the following values:
    Bank One:
    Cylinder 12 170
    Cylinder 11 170
    Cylinder 10 150
    Cylinder 9 160
    Cylinder 8 160
    Cylinder 7 170

    Bank Two
    Cylinder 1 175
    Cylinder 2 180
    Cylinder 3 185
    Cylinder 4 180
    Cylinder 5 160
    Cylinder 6 180

    Any thoughts and education is appreciated


    Sent from my iPhone using FerrariChat
     
    Llenroc likes this.
  2. Al Campbell

    Al Campbell Formula Junior
    Owner Silver Subscribed

    Nov 22, 2013
    571
    Australia
    Cylinder 5 is not good - a leak down test can better diagnose the reason why.

    Cylinders 7-12 all low like that indicate poor camshaft alignment on the left bank possibly due to timing chain stretch.

    I would say it will probably need an engine out service soon to replace timing chain, chain guides and valve guides soon.
     
  3. raemin

    raemin Formula 3

    Jan 16, 2007
    1,825
    Lyon (FR)
    Full Name:
    R. Emin
    Cylinder 5 has probably some thin cracks on the cylinder dome. No point in trying to fix such a failure with "block-seal", only way to fix-it is engine-out or make it do with a slight leak.

    In fact you can remove the head(s) without an engine-out. For the stretched chain, it is also possible to replace it without an engine out. My mechanic replaced one of these as follows "cut" the old chain, fix the new chain together with the older one, perform a complete chain revolution, remove old chain, check camshaft alignment marks. When my mechanic did it in another client's car it seemed damn easy, but could be a challenge...

    These are the few solutions you may try if you do not want to perform a full engine overall. That's how my engine repair started. Unfortunately if the chain tensioners are worn-out you will have to drop the engine out of the engine bay (that's how my engine repair ended).
     
    Il Tifoso likes this.
  4. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,591
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    Just drive it!
    Ken
     
    365boxer, Il Tifoso and raemin like this.
  5. raemin

    raemin Formula 3

    Jan 16, 2007
    1,825
    Lyon (FR)
    Full Name:
    R. Emin
    Got to agree: either spend $10k~$20k or make it do with a few missing HPs and enjoy the car.

    I've promised myself that any new resto that prevents me from enjoying the car will be avoided in 2021!
     
    Il Tifoso likes this.
  6. 365boxer

    365boxer Formula Junior

    Sep 30, 2004
    389
    La Drova, Spain
    Full Name:
    Nick
    Could not agree more, the readings barely even deserve discussion !
     
    GTR-Man likes this.

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