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Thread: mysterious rattle

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  1. #1
    Join Date
    Jul 2014
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    Default mysterious rattle

    As I noted on my fuel pump thread, what was a faint intermitant rattle before I left on a business trip has become an alarmingly loud rattle. I've uploaded a short video to youtube here (https://youtu.be/gsbGi-AGlk0).
    I don't have any idea at all of what is causing it. A wild guess is that a belt tensioner is loose...??? I removed the belt cover from the rear bank to give a quick look, but of course I can't observe it running since the Xdi triger wheel sensor is mounted on the cover I removed. I'll get it to TDC and lock the cams before I start taking things apart. In the meantime, if anyone has any ideas... Any ideas will be much appreciated.
    Thank you as always for your help & support.

  2. #2
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    Short of a blown out exhaust gasket and/or sniffer tube bung, it should be obvious. Disassembly required.
    Sarasota Italian Garage, LLC
    "The Fluent in Ferrari Guys" celebrating 37 years of service excellence
    **An independent facility with no affiliation with Ferrari SpA**
    Sarasota, FL
    www.fluentinferrari.com

  3. #3
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    Jul 2014
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    Thanks for chiming in Radioman.
    I must have jinxed myself remarking how good she's been running earlier. It really has been running great since I adjusted the valves, synchronized the carbs and installed the Xdi. I'm hoping I don't have to pull the engine, but she does have a lot of miles on her. Not how I was planning to spend Spring, but at least the garage is warm enough to work in... I just wish I knew what I was doing... Oh well, another learning experience - wish me luck!

    Thank you again!

  4. #4
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    One notorious place for a rattle in the 308 is the A/C hoses banging against the place where they go into the bodywork from the compressing. The factory "fixed" it by wrapping a little foam around them and stuffing it inside that opening. Many people have removed that foam for some reason when working on the timing belts (and moving the AC compressor) then ended up with a loud rattle that sounds horrendous, but is actually harmless.
    Birdman308 for parts and tutorials!

  5. #5
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    Jul 2014
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    Thanks for the tip Birdman.
    I'm going to put the belt cover back on, so the Xdi works; and spend some more time trying to isolate the rattle before I take too much apart. I'm afraid Radioman's right about needing to dissemble; I just want to keep disassembling to a minimum.

    Thanks again guys; I sincerely appreciate the support.

  6. #6
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    I put the belt cover back on to run the engine, and look for the rattle; and I think I found it. I THINK it's the cam belt lower drive pully # 104914 (Puleggia conduttrice) #28 on TAV 8. I've uploaded another video to youtube here (https://youtu.be/IBN-4iWKEjw); see how the cam belt lower drive pully jumps around? (shaky hands don't help). That jumping around could be normal for all I know, but I noticed that the rattle conincides with the dancing dimple in the pully shaft. I would expect some jumping of the tensioner, but not the drive pully...??? Anyway, it looks suspicious to me.

    I seem to remember running accross a tutorial on how to replace those. IIRC it involves drilling a hole to pull the old ones out..... I'll start my search for that tutorial now. In the meantime, If anyone has any remarks or suggestions, I'm all ears.
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  7. #7
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    Video link isn't working... Regardless, there should be zero movement on the lower drive pulleys. The design/support improved as the cars evolved. How long ago did you do belts? As I said earlier, disassembly required.
    Sarasota Italian Garage, LLC
    "The Fluent in Ferrari Guys" celebrating 37 years of service excellence
    **An independent facility with no affiliation with Ferrari SpA**
    Sarasota, FL
    www.fluentinferrari.com

  8. #8
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    Radioman:
    Thank you so much for your quick response. link: https://youtu.be/IBN-4iWKEjw should work...???
    Last did belts August 2014, but I didn't touch the drive pulleys (didn't seem to need at the time). I did adjust valves, replace cam seals (dropped a nut down an oil channel) changed cam belts and tensioner bearings. I was planning on doing next belt change next year (5-year intervals), but I guess I'll need to move that up.

    I didn't doubt you for a minute that disassembly would be required..... how difficult is it to change the drive pulley bearings while doing the belts? Will email you re parts.

    Thank you again!!!

  9. #9
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    Ceramic coating is basicly powder coating a high temp fusable powder, so everything gets coated inside & out.

    You really should remove all heat shield remnants, especially the collector shield as the collector area is one of the more common areas for corrosion to set in.
    When it's NLA, Who do you call? Unobtainium Supply Co.

  10. #10
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    Quote Originally Posted by Verell View Post
    You really should remove all heat shield remnants, especially the collector shield as the collector area is one of the more common areas for corrosion to set in.
    Verell: Thank you for clarifying.
    Just to be sure, the areas marked in red of the attached need to have heat shield removed for ceramic coating... Sorry to be repetitive, but I don't want to cut where i shouldn't. I already cut into part of the collector that was hidden by the shield. Does it help to ceramic coat the cats or the muffler?
    Fireman: you were right about that part of the heat shield being very tough metal. Much more so than the bulky aluminum shield.
    Thanks again & kindest regards
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