Belt noise turn out to be pandoras box | FerrariChat

Belt noise turn out to be pandoras box

Discussion in '308/328' started by mexicruiser, Mar 12, 2020.

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  1. mexicruiser

    mexicruiser Karting

    Aug 28, 2012
    241
    Full Name:
    Jon
    This is one of those cases where “I’ll just fix this one thing” combines with “while I’m in there” + “previous Owner wrongdoings” resulting in another partially disassembled car.

    While fixing a stumble/hard start issue on my GTBi 2v caused by a bent air sensor plate (flattening the air sensor plate was interesting, used two heavy gauge bottom induction frying pans on the stove and about 20 pounds of weight) I noticed a timing belt whine and decided to check it out causing this chain of events:
    -remove water pump belt, noise continues
    -remove ac belt, find it to be severely overtightened because of missing spacers on top bracket, noise continues.
    -remove timing tensioners and find them to have belt material on the friction surface, too thight perhaps?
    -notice cam bolt locks are not bent in position and washers are on backwards pushing against the gear pins, remove to find damaged o rings and lots of silicone.

    At this point, seeing all this marvelous workmanship, I wonder if the cams are correctly timed and decide to pull the covers:
    -cams have marks aligned, decide to check valves, only two intake valves are off (.007” and .012”)
    -decide to remove cams to check required shim size, find 5 caps are missing their guides, some caps appear to be installed upside down, but not sure at this point.

    This is where I decided to stop, or else things are going to escalate (still have my bbi engine out project to be continued) I will have to hope “they” didn’t work on the bottom end.
    Ordering new shims, pins, seals, gaskets, belts, etc. hopefully bolting the pulleys properly and new belts/tensioners will fix the noise, plus I will fix everything else I encountered.

    Anybody have recommendations or observations on things so far? Thinking of dialing in cams to euro spec? remapping the digiplex’s timing curve?
     
  2. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    33,736
    Austin TX
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    Brian Crall
    I would pay close attention to the lower drive bearings as a source of noise. Belt rubber transfer on the tensioner pulleys isn't very uncommon on the old heavy factory style bearings. There is some slipping involved during rapid acceleration. I don't think retiming the cams will do much. Not sure what it will take to change timing in the Digiplexs but that should yield some good results. US cars had very conservative timing to keep HC down.
     
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  3. mexicruiser

    mexicruiser Karting

    Aug 28, 2012
    241
    Full Name:
    Jon
     
  4. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Brian Crall
    Everything needs to be undone to evaluate them. In 43 years working on them professionally I have never found a need to replace the inners. When a motor is out and apart I do but not on an in the car repair.
     
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  5. mexicruiser

    mexicruiser Karting

    Aug 28, 2012
    241
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    Jon
    What does the wsm state on the cam caps, on their orientation? Anybody has this info? They are marked 1 to 20 but on my car not all the caps were equally oriented.
     
  6. GordonC

    GordonC F1 Rookie
    Owner Rossa Subscribed

    Aug 28, 2005
    4,119
    Calgary, AB, Canada
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    Gordon
    May be too late - but you need to note the orientation before you remove them. It varies randomly, and you should ideally put them back in the same orientation which they had when removed.
     
  7. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    At the factory, the caps are put on, machined to the heads, and engraved with a number. The orientation of the numbers on a single head is uniform in one direction. It may not be the same direction with the other head, but all caps on the same head face the same way.
     
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  8. mexicruiser

    mexicruiser Karting

    Aug 28, 2012
    241
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    Jon
    I have a picture before disassembly, I just want to verify and see if I have to change anything as I do not trust the shop that rebuilt the engine.
     
  9. derekw

    derekw Formula 3
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    Sep 7, 2010
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    Derek W
    All of my caps were stamped with a number on the outside... except one. When I tightened that cap the cam locked. Reversed it and it turned. No signs of wear so obviously a human error.
     
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  10. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Brian Crall
    Not at all. They are all marked at the factory.
     
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  11. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Brian Crall
    Yup. The numbers can be hard to see or read but they are there.
     
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  12. GordonC

    GordonC F1 Rookie
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    Aug 28, 2005
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    Gordon
    Apologies, I was referring to the part number molded on the cam caps - on my QV, they were not all oriented in the same direction. The stamped numbers, however, were uniform as both of you corrected.

    I also shouldn't assume that my car is necessarily correct anymore, all I can attest is how it was when I bought it! Prior mechanical work may have been done incorrectly.
     
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  13. mexicruiser

    mexicruiser Karting

    Aug 28, 2012
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    Jon
    Ok, so the part numbers on the caps can be either way as long as the stamped numbers are propperly oriented, thank you. Ordered the parts and hoping they won’t be delayed too much because of the covid-19 thing. Also ordered the outer cam drive bearings and the draper puller (wonder if I can use it on the bbi?) In the meantime I will be fixing some electrical issues. Having both cars disassembled is stressing me out, but I thought the 308 would be an easy fix.
     
  14. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    26,292
    socal
    While mitchel is correct you could still have a problem. Proper and complete rebuilding includes line hone of cam bores. If the rebuilder randomly placed the caps and line honed then you want to keep the caps in that random position. Then there is derek below and I also have seen this once in 40 years. I guess that car was rebuilt? I did not think much about it at the time.

     
  15. mexicruiser

    mexicruiser Karting

    Aug 28, 2012
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    Jon
    Would removing the lifters allow the cam to be turned without hitting the valves? I would like to check for bind before I tighten each cap just to be sure.
     
  16. derekw

    derekw Formula 3
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    Sep 7, 2010
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    Derek W
    You might get a little movement before one of the lobes touches the valve or spring cap. Hopefully someone more experienced knows and can advise. You could also use the cord-down-the-plug-hole trick to remove one valve's spring and cap then lower valve (not easy for front bank with engine in-situ.)
     
  17. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    I have never seen it.
     
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  18. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    33,736
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    Brian Crall
    No, can't really do that. The best that can be done is to put the other bank on TDC so all the pistons on this bank are down and you can turn the cam through. You will be able to feel free cam movement between valve opening and closing events.

    The cast in numbers should all face the same way (thats how Ferrari builds them) with indexing numbers matched.
     
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