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355 Timing Belt Question

Discussion in '348/355' started by huzilulu, Jan 17, 2024.

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  1. huzilulu

    huzilulu Formula Junior

    Apr 20, 2011
    340
    Houston
    Full Name:
    Huzi Husain
    #1 huzilulu, Jan 17, 2024
    Ive just started my major, and had a question at the get go... After engine removal, the first thing I did was remove the belts and remove the timing cover to expose the timing belt.. What I have noticed is that the LH Timing belt when looking at the engine (US Pass side) : the bearing is leaking grease, the hyd tensioner seems to have failed/collapsed, and the belt has no tension on it (or very little due to the bearing being installed but not 'tensioned' due to the hyd tensioner failure)... The RH side is proper - belt is tensioned, and both bearing and hyd tensioner appear to be in good working order...

    My question is: I have been driving the car prior to the engine out, and did not notice any engine issues... On the other hand, the car is new to me, so I am not sure if it should be driving any differently than it was... Could this failed hyd tensionser have caused any problems I should check for? Can i rotate the crank and check the timing in the current state?

    Thanks!!

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  2. bobzdar

    bobzdar F1 Veteran

    Sep 22, 2008
    6,892
    Richmond
    Full Name:
    Pete
    #2 bobzdar, Jan 17, 2024
    Have you verfied it's failed and the belt just isn't in a position where there's slack on one side due to the valve springs/cam position? If you rotate the engine you should see the tensioner move a bit. I had original tensioners on mine when I did my last major and replaced them, not difficult at all. Very low risk to rotate the engine by hand, will also show if the tensioner is really bad or not. If it didn't let got at a few thousand rpm, it won't have any issues at 1rpm.
     
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  3. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,614
    The Brickyard
    Full Name:
    The Bad Guy
    #3 ernie, Jan 17, 2024
    All I am going to say is,

    Get a set of Hill Engineering cam belt bearings.
     
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  4. spaghetti_jet

    spaghetti_jet Formula Junior

    Jan 5, 2005
    925
    Europa
    Full Name:
    Bob
    #4 spaghetti_jet, Jan 19, 2024
  5. cactussed

    cactussed Formula Junior

    Mar 12, 2008
    286
    #5 cactussed, Jan 19, 2024
    I'm no mechanic but have don'e a few belt changes myself.
    You may just have gotten lucky is all. There should be tension in the belts and the tensioner should push out without the bearing in the way.
    If not, get a new tensioner, and has been said, get some hills bearings.

    If the timing was off, you'd know about it (trust me).
     
  6. spaghetti_jet

    spaghetti_jet Formula Junior

    Jan 5, 2005
    925
    Europa
    Full Name:
    Bob
    #6 spaghetti_jet, Jan 19, 2024
    my experience was as you described. The tensioner looked like it had “collapsed” but it moved and kept tension as the load on the belt changed when turning the engine over by hand. The probability of total failure (seized plunger or broken spring) is very low.

    It’s quite possible that it wasn’t set properly during the last belt change.
     
  7. huzilulu

    huzilulu Formula Junior

    Apr 20, 2011
    340
    Houston
    Full Name:
    Huzi Husain
    #7 huzilulu, Jan 19, 2024
    An update: I turned the engine over by hand a couple times and it appears that the tensioner in question does tension the belt for about 50% of a crank turn, while it is 'off tension' for about 50% of the remaining turn.. Im not sure if this is a design element, but I could not duplicate it on the other side..

    Either way, my major will be replacing almost everything at this point: belts, bearings, hyd tensioner, seals, rubber hoses, etc etc... More to come over the next couple months as I dig deeper into the hole :)

    Meanwhile - this past week I was able to fight off a few super rusted/frozen nuts and get ONE header off... the nuts were seized and one was partially stripped - maybe from a previous attempted removal !

    I've also pulled off the PS pump and Waterpump and both are being rebuilt with new seals/parts as needed... pictures to come next week
     
  8. taz355

    taz355 F1 Veteran
    Owner Silver Subscribed

    Feb 18, 2008
    6,016
    Indio Ca/ Alberta
    Full Name:
    Grant
    #8 taz355, Jan 19, 2024
    You can turn the engine over and line up the build marks
    That will tell you if it’s jumped a tooth very quickly.
    Likely it has not
     
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  9. cactussed

    cactussed Formula Junior

    Mar 12, 2008
    286
    #9 cactussed, Jan 22, 2024
    One thing. If you rotate the engine the wrong way, the tensioners and belts do weird things and one side will go slack etc.
    Turning it in the right direction sorts them out. Just from having done it out of curiosity.
    As you're replacing the lot, then there's no issue.
     
  10. WATSON

    WATSON Two Time F1 World Champ
    Owner Rossa Subscribed

    Sep 9, 2010
    23,679
    WI
    #10 WATSON, Jan 23, 2024
    Get a news set of tensioners and all will be fine.

    When I did my engine out I was surprised at the gap differential in the tensioners right to left. Non-Ferrari belts I might add.

    I suspect what you are seeing are tired tensioners and stretched out belts. Your decision for an engine out service seems wise.

    BTW, buy your belts from Ricambi. Daniel sells Ferrari certified belts. These are cut from the center of the extrusion and sold as sets cut next to each other for even stretching.

    More pictures of your progress please..... :)
     
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