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  • Guest's Avatar
    Guest replied
    Originally posted by 365Lusso on December 11, 2013 7:02 PM
    Jacques, thank you for sharing with me your hard-earned experience. My chassis (16251) is very close to, and has the same later tensioner housing as yours. I don't have any plans to replace the chain, so it won't be a problem. Regards, Wil

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  • Guest's Avatar
    Guest replied
    Originally posted by Trachsel on December 10, 2013 5:55 PM
    Hi all, first of all check which tensioner your car has. If it is the tensioner of the second serie, compare TAV 6, Fig 8 with http://www.eurospares.co.uk/userImag...ge/064_006.gif . (Tensioner housing) You can see, that 365 gt 4 2+2, the succeder of our 365 gtc4,there is the difference, that you cannot fix the tensioner. My car, 16 273, has allready the modification for the 365 gt 4 2+2. So, when I changed the chain, I made the mistake, not to take out the cams first. When I opened the chain, the tensioner spring pushed the tensioner and the chain turned the cams - 4 valves destroied ! Please pay attension, late cars will have the modifications for gt 4 2+2. Regards, Jacques

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  • Guest's Avatar
    Guest replied
    Originally posted by Ian Levy on December 10, 2013 7:32 AM
    Aaron
    Interesting for me is the huge difference between early to late chain tensioners.
    It looks to me that the early version(pre 15181 & 15289) is of lighter construction as is the original oil/water pump chain tensiner.
    The late tensioner looks to be considerably bigger with a much,much heavier spring.
    How did the early arrangement manage to put sufficient pressure on the chain?
    Ian L

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  • Guest's Avatar
    Guest replied
    Originally posted by 365Lusso on December 10, 2013 3:31 PM
    Aaron,
    Your second time around describing the chain issue made it click. I wasn't letting go of the idea that chain tension is correctly set by spring tension alone: it is actually set by the fully bound/compressed spring stack (minus 1/4 turn for play). That would explain the very brief turning range (one turn in this case) from humming tight to clacking loose. That was really bugging me. The spring by itself is not strong enough to hold proper chain tension, so the chain will clack--or worse--throughout most of its adjustment range. The chain will clack until the spring is all the way compressed.
    My engine does the same thing when the chain is too loose--the clacking goes and comes back when revved and dropped back to idle.

    Thanks much--that was great to have the light bulb go off,
    Wil
    Originally posted by Aaron
    When the chain is too loose, I would describe it as more of a clacking and it definitely changes as the engine is reved and dropped back to idle (idle to 2000) rpm.
    ........my belief that the tension is not a function of the spring, but a function of the location of the where the tension shoe can not move anymore.

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  • Guest's Avatar
    Guest replied
    Originally posted by Aaron on December 10, 2013 7:18 AM
    Wil
    I agree - that whirring sound described, "sounds" like the sound when the tensioner is too tight, and is where I back the tensioner out to make go away.
    When the chain is too loose, I would describe it as more of a clacking and it definitely changes as the engine is reved and dropped back to idle (idle to 2000) rpm.
    I will re-iterate, I believe the chain play is a hard adjustment of the location of the tensioner shoe and the spring is just there to take that small amount of
    excess. So I think you have done it correctly if you back out your quarter turn from where the whirring goes away.

    When I had the covers off, pushing with a gloved thumb on the chain between the left cams, I could feel the chain tighten as I turned in the tension adjustment.
    I could press on the chain, compress the spring in the chain tensioner and tighten it up against the chain "hard stop" location. When the chain is flying around
    at 6000 RPM, I'm sure the forces are much greater than my thumb, which is how I justify my belief that the tension is not a function of the spring, but a function of
    the location of the where the tension shoe can not move anymore.

    I'm at loss as to why you do not have an intermediate "quiet adjustment" . Could there be something else contributing to the BB on the wash board noise,



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  • Guest's Avatar
    Guest replied
    Originally posted by 365Lusso on December 10, 2013 4:18 AM
    Ian, one of the things that make this a hard subject to chat about is that describing the noises can't be put into easily understandable words or ideas. It would be great if we could upload videos to this Forum, but I do understand how that is a real bandwidth consumer. Maybe put a video on YouTube with a link to it here. I suspect the chain sounds would be hard to discern from the general good engine noises in a recording, but might give it a try.
    I've studied off and on over time Figures 20 & 21/1 in the manual, trying to understand what is going on with my tensioner (it's been doing it for a couple of weeks--I don't drive it much at all now), thanks for sending Fig. 20 to me. I have always greatly appreciated your unflagging patience and kindness in helpfully answering fellow member questions.
    Very Best Regards,
    Wil
    Here's the apropos diagrams:





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  • Guest's Avatar
    Guest replied
    Originally posted by Ian Levy on December 10, 2013 1:54 AM
    Hi Wil
    I am not sure of the BB & old washboard noises as my noises have only been rubbing or grauching noises.
    Interestingly these noises only began after the engine rebuild when all new chain pads were fitted.
    Also other than the pad on the chain tensioner there are four other pads.
    One under each top chain cover
    One under the chain between the idler gears
    One on the opposite side of the engine to the chain tensioner.
    Any or all of which could be worn.
    I will try & upload some pics
    Best
    Ian L

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  • Guest's Avatar
    Guest replied
    Originally posted by 365Lusso on December 10, 2013 3:45 AM
    Mike, that would be a real help if you could do that. The booby-trap I think awaits if I pull the entire tensioner ass'y out is that a cam or cams will move independently of the crankshaft too much and thus cause a valve to hit a piston. Thanks much for your thoughts on my confusing tensioning matter.
    Best Regards,
    Wil
    Originally posted by Zanny1
    Next time I pass by the repair facility (Cavallo Motorsports in Carlsbad, California), I'll ask them about the difficulty in removing the chain tensioner and if it can be done externally.

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  • Guest's Avatar
    Guest replied
    Originally posted by Zanny1 on December 10, 2013 12:25 AM
    Wil, I don't recall hearing a sound as you describe on my car. The tap in the vicinity of the vacuum pump is intermittent, seems to go away when the RPM's increase, and in no way sounds like BB's poured on an old fashioned washboard. So we are talking about 2 different conditions, I believe. Next time I pass by the repair facility (Cavallo Motorsports in Carlsbad, California), I'll ask them about the difficulty in removing the chain tensioner and if it can be done externally. I would not be surprised if your tensioner pad is worn out.....the resonating/humming you describe sounds like the chain is too tight, and using that as a data point, if the other sound returns when loosening the chain slightly then the noise probably originates at the tensioner. I don't have my shop manual as Cavallo is copying it for their technical library. Thus I cannot look at the mechanism and it's components at the moment. Good luck - Mike

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  • Guest's Avatar
    Guest replied
    Originally posted by 365Lusso on December 9, 2013 10:33 AM
    Mike, hope that turns out to be a benign 'tap' if there is such a thing. You should be in good shape having a shop that backs its work. If it was a valve clearance issue it would be a steady tap. Maybe only something going on in the vacuum pump itself, which would be good news.
    Regarding my tensioner issue, it sounds like BBs being poured over an old-style washboard, kind of a streaming, loosey-rattly sound, seems like a too loose chain sound. The engine has quite a few other sounds, but none of them sound unfriendly. No clicks, taps, or whines. A few days ago I tried tightening the tensioner one turn and the engine started making a resonating humming-whirring kind of sound, seemed like it was too tight. So I went back a turn to the loosey-rattly sound which seems better. The in between area in that one turn of the tensioner doesn't get quiet either, just kind of blends from one to the other sound.
    After studying on it a bit, it seems that the tensioner should have a range, either large or small, where the spring is in optimal compression by the Tensioner Peg. When the Peg is turned way out, the chain will be too loose. As the Peg is turned in, the loose chain sound will go away and the chain will move into proper tension. As the Peg is turned further and further in, the chain will become tighter on a linear slope (assuming a non-progressive spring), until the spring is fully compressed; somewhere along that turning range the chain will become too tight. If the Peg is turned even further (with a fully compressed spring), the chain tension will rise on a far steeper slope, not good.
    What I would like to establish is where my particular tensioner is on that spring compression/tightening scale. Is it right on the edge of spring-binding, solid column compression, and thus the resonating humming-whirring sound? Is the Peg so far turned out that the spring is not compressed much at all, and thus the streaming loosey-rattling sound? If that is the case, then why does just one turn make the chain take on that resonating humming-whirring as if the chain is too tight sound? It seems that there should be a range of several turns of the tensioner between a too loose and a too tight sound. Or I'm not interpreting the sounds correctly--just dunno.
    I thought of removing the tensioner ass'y altogether to have a look at the rubber pad and to try and figure out where in that spring compression range my tensioner is now, but I bet there are nasty booby-traps waiting to pounce should I try that.
    Wil

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  • Guest's Avatar
    Guest replied
    Originally posted by Zanny1 on December 9, 2013 12:05 AM

    Wil, can you describe the noise you are hearing in the timing chain area? Is it a tap, a whine, a click.... can you feel anything by placing your hand in the area? These motors are not as quiet as one would expect. I recently had the opportunity to witness a GTB/4 motor idling, fully hot, and was amazed how noisy it was. The motor had about 6K miles on a pro rebuild. My motor just hit 2K miles on a fresh overhaul, and makes the same amount of whirs, clicks, taps and such.
    I do have an intermittent "tap" in the vicinity of the vacuum pump, which is currently being checked by the shop that did the rebuild. I would be interested to hear from other C/4 owners in regards to these noises.... in particular any tapping in the area adjacent to the vacuum pump.
    Mike


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  • Guest's Avatar
    Guest replied
    Originally posted by 365Lusso on December 8, 2013 6:01 AM
    Ian and Aaron,

    The thing that is hard to deal with in this case is my lack of ease and ignorance in dealing with this aspect of an incredibly expensive vintage Ferrari engine. It makes my normal sense of feel for old (Brit, for instance) engines go out the window in this case.

    Would this work as a way to get more feel for the tensioner?: 1) while the engine is cold and stopped, count the number of threads showing on the Tensioner Peg; 2) unlock the Tensioner Peg, and start turning it inwards with an 8mm allen key until it hits some kind of hard stop (I guess it wouldn't be a 'hard' stop, more like a sudden increase in the effort needed to turn the allen key)--that would be when the spring is fully compressed and the tensioner would be pushing as a 'solid piece' on the chain. Then back off to the starting point thread count and re-lock.

    After doing that, I will know when the tensioner hits the 'hard point' when I warm the engine through and start tensioning the chain for real. For further familiarization, I could start turning the tensioner both in and out while the engine is warm and idling to see what kinds of noises the chain makes as it is loosened and tightened.
    Does this sound Ok?

    Thanks,
    Wil

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  • Guest's Avatar
    Guest replied
    Originally posted by 365Lusso on December 8, 2013 5:50 AM
    Jacques, thanks for the tip, makes sense. I guess I won't be pulling just the cam sprocket covers, as I don't want to pull the studs. In the past on other engines I've had studs pull part of the ali threads out with them, don't want to risk that. Regards, Wil

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  • Guest's Avatar
    Guest replied
    Originally posted by Trachsel on December 8, 2013 5:05 AM
    Will, if you want to only remove the cam sproket covers, then you have to turn out all studs, so you can move the covers to the front and then lift them up because the o-ring is located in the timing chain cover, not in the cam cover. Regards, Jacques

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  • Guest's Avatar
    Guest replied
    Originally posted by Aaron on December 8, 2013 3:06 AM
    Will,
    Not sure to what to tell you about the "goop". I will strongly agree with Ian, anything beyond a light tap is risky. Flexing the cover
    sideways can dammage the surfaces..... I have never removed a cam chain cover with out the valve cover off. With the valve cover
    off, it much easier to grab hold of.
    Tentioning the chain most definately involves compressing the spring and to reach the point where it starts to make funning
    rubbing noises, it is compressed all the way and dragging on the chain. So what I do is compress the spring in the
    tensioner all the way and then back it out, (I actually went a half turn, even though the manual calls for a quarter.) Also it is improtant
    to do this with a hot engine. It is my belief that engine gets bigger when hot, increasing the distances between the gears. When doing
    this, (with the exception of the lock nut) very little turning force is required. So get cofortable under the car, listen and feel as you turn in the
    tensioner. On my car the "rubbing" noise was periodic. Play with it to find the point where all rubbing noise has completely disapeard and
    then do the back out, and tighten the lock nut. So - the chain tension is actually a solid mechanical adjustment allowing for a small amount of play.
    The sping in the chain tensioner is there to take up that small gap. This has worked for me and I have driven my car 43,000 miles.


    Regarding pulling just the cam chain cover. Hmmmmmm - If I was going to pull the a cam chain cover, especially on an unknown engine assembly, I would start
    by removing the valve covers and this is Why -
    Typically the O ring will reside in a slot in the cam chain cover. If he cam chain cover is pulled, it will stretch the O ring. o get the cam cover off, the O ring
    will break. The issue here is "where will it break". If it breaks nicely at the top, you are in good shape, however, if breaks at the bottom between
    the timing chest and the block, that is a major problem and the correct way to fix that would be to remove the timing chest. (I have heard of
    people pulling new O rings through the slots between the engine and timing chest, but have no experience doing that my self - It may work fine)

    If the Valve covers are removed, then it is simply a case of pulling the O ring towards the rear, out of its slot in the came chain cover before removing the covers.
    As I side note, I have made it a habit to cut the O rings at the top so I can thread them through the valve/cam chain cover gaskets.








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