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ISB noise, or loose flywheel bolts??

Discussion in 'Engine Tech / Drivetrain' started by RKSskier, Feb 4, 2010.



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  1. RKSskier

    RKSskier New Member Registered VIP 5+ Year Member

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    I have a little noise coming from under the hood. I believe it to either be a loose flywheel bolt or noise coming from the input shaft bearing. Here are some things I have noticed about it.
    -It sounds like a tiny metal bell ringing
    -It is audible when the car is first started, and for at least 5-10 minutes
    -after driving a bit it seems go away, or at least I don't notice as much
    -I can only hear it when idleing or going very slow (not that loud)
    -It goes away when I put the clutch in (why I think it could be isb)
    -however when I have heard isb's showing wear, it sounded more like a brushing noise than a bell ringing
    -I recently swapped a replacement block in and didn't use any loctite on the flywheel bolts allthough they were torqued to spec.


    The fact that it goes away when I put the clutch in makes me think it is the isb, but I figure that it is possible that it could be the flywheel bolt(s) and when the clutch releases it is no longer at a vibration that causes resonance.

    Maybe something else in the tranny?

    Any help would be appreciated.
    thanks
     
  2. s_crowley 17

    s_crowley 17 New Member Registered VIP Registered OG 5+ Year Member

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    ISB would be more of a 'brushing' type of noise.. and you would in fact hear it in most gears (loud and very noticable)

    I think you might be able to factor that out.
     
  3. RonJ

    RonJ Banned

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    Have you carefully checked the exhaust heat shields? They might be bent, loose, or cracked.
     
  4. Chris.

    Chris. Stickin' it to the man Registered VIP Registered OG 5+ Year Member

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    id be more leaning towards the throwout bearing... or the pilot bearing

    the pilot bearing is in the flywheel... and supports the long end of the input shaft.
     
  5. RonJ

    RonJ Banned

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    I think a bad throw out bearing typically makes noise only with the clutch pedal depressed.
     
  6. RKSskier

    RKSskier New Member Registered VIP 5+ Year Member

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    I have had a isb going bad before, and it was more of a brushing, different sound, but I was not/am not certain that it couldn't make another sound. Also when I had the isb noise before I couldnt hear it driving except going pretty slow
     
  7. RKSskier

    RKSskier New Member Registered VIP 5+ Year Member

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    What exhaust sheilds?? No heat sheilds are on the car, there is the sheild/guard thing (flywheel cover is on of course) but like I said the noise goes away when the clutch is pushed in, so I wouldnt think that could do it.
     
  8. RKSskier

    RKSskier New Member Registered VIP 5+ Year Member

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    I am not familiar with what type of noises or even all symptoms of either of those going out. However when the clutch is out the noise is there, once it is in it is not. Would those both be more of a constant noise if they were the issue? Since they are on the flywheel side so pushing in the clutch just dissengages contact (well rotation) of the transmission.

    I heard something a bit back from people talking about a rattling of flywheel bolts before bad things happened. I don't know why it seeminly goes away or mostly away once warmed up though, and wonder if that will be key in figuring it out. I don't want to have to pull the tranny off.
     
  9. RKSskier

    RKSskier New Member Registered VIP 5+ Year Member

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    Here are some of the things that i've seen:
    http://www.dsmtalk.com/forums/showthread.php?t=131511


    I am also thinking that if it gets worse quickly, or if it the rattling starts happening in nuetral then those could be signs of flywheel bolts.

    So anyone know if isb's always make more of a brushing noise, and isn't ever really a rattling/ringing?

    Anyone know of any other parts that rotate with the transmission not the motor, that could make this noise?
    -Internal tranny parts


    And thanks guys I appreciate the willingness to help. I hope it's the isb or something in the tranny, and not flywheel related. I also hope I can get a good idea of what it is without pulling the whole motor and tranny out.
     
  10. RonJ

    RonJ Banned

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    So you have removed all of your exhaust heat shields?
     
  11. RKSskier

    RKSskier New Member Registered VIP 5+ Year Member

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    Correct, there is no exhaust manifold heat shield on the car, and the catilytic converter is not stock and doesn't have one.
     
  12. RKSskier

    RKSskier New Member Registered VIP 5+ Year Member

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    So today I was a little more observant as I wanted to see the difference from the initial startup to arrival and destination. So with the car in neutral before being started, it makes the noise. It is there and not super loud but easy to hear. The car takes less than 5 minutes to get to operating water temp, and I could hear the noise while driving, (clutch out, and in gear). After about 15 minutes it appeared to have gone away or at least diminished. 20 minutes I am at my destination and when I parked I could no longer hear the sound, and couldn't tell the difference between clutch in or out, both at idle, and free reving about 2000 rpm. Also I figure if it happened to be a flywheel bolt that it could likely make some sort of noise when free reving even if the clutch was in, however free reving and letting off the gas quickly at 1500,2000, 2500, and maybe 3000, never heard it.

    thanks guys
     
  13. RonJ

    RonJ Banned

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    You may very well have a bad ISB. I am only chasing out the exhaust heat shield possibility because I had a noise similar to yours and it turned out to be a cracked exhaust heat shield. I would push the clutch pedal down and the noise went away. In addition, noisy exhaust heat shields are very common problems with Civics. Have you also removed the shields circled in red in the diagram below?

    [​IMG]
     
  14. RKSskier

    RKSskier New Member Registered VIP 5+ Year Member

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    It has an aftermarket catback, and I can hear the noise coming from under the hood.

    I recently changed the doughnut gasket between the exhaust manifold and the cat, and I believe that those bolts/nuts have come slightly loose (maybe gasket wasn't properly torqued and the gasket compressed more) Anyways I think that is one slight noise, but I don't think that is it, but I will still have to tighten that up before I can know that it isn't it.

    Anyways I stopped at a tranny shop today and the owner took a look and test drive and I explained it's symptoms, he said tranny bearings can also make a light ringing/rattling, like i am hearing, and said that the fact that it goes away shortly means it is in the very early stages of wear, and that it is quite common with honda trannys. I was aware that the isb was commonly an issue, and that many times it could last a while, and he aggreed at the end that it was tranny bearing noise, and that it wasn't even close to bad enough to be worth doing anything. I mentioned that I was concerned about a possibility of a flywheel bolt backing out, and he said he wasn't worried about that, and explained why and what would have to happen first.

    So I am going to assume it is bearing noise from a tranny bearing, and keep driving the sucker. I will rev it up and not worry about flywheel issues, but I will be keeping an eye on it. I figure if it is bearing noise and is very minimal that it shouldn't get worse very quickly, but if it is a loose bolt it could get worse very quickly especially if it is taken to high rpms. So i will probably just be paying attention to it closely for the next few months to make sure it doesn't seem to change.

    Anyways thanks for the help guys. I appreciate it and I am glad it appears to be okay.
     
  15. B18c_SICoupe

    B18c_SICoupe New Member 5+ Year Member

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    throw out bearing deffently!
     


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