Noise reduction

Discussion in 'General, Performance Upgrades & Accessories' started by Woofythewolf, Dec 15, 2016.

  1. Woofythewolf

    Woofythewolf Registered User

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    My problem:

    My oil pan is over 110 decibels, by far the loudest part of anything on my truck (even the exhaust is only 87-95), and I (and my neighbors) don't like hearing that at 7:00 am every day.

    Solution: decouple the oil pan

    How: put 1/4" thick layer of RTV silicone gasket maker between the oil pan and the engine. Hold it in that position with bolts until RTV cures at 1/4".

    Next: take a bunch of big washers (like 1" round but one side shaved to clear oil pan) and put another 1/4" of RTV on one side, and screw in at 1/4" gap until cured. Then tighten a yet to be determined amount.
    -probably want to do half at a time (alternating every other) so the oilpan is always supported

    Things I need-
    oil pan bolts that are 1/2" longer
    A whole bunch of tubes of RTV (like 6 maybe?)
    1" fender washers with some shaved off one side. (Make sure they won't touch the oil pan)

    Result-
    Should smooth out the vibration to the oil pan.
    I expect that it will still vibrate with the engine, but higher frequency vibrations would be greatly reduced, resulting in a much smoother sine wave for the sound (meaning a smoother, lower pitch and lower frequency sound)

    Potential questions:
    Will the RTV silicone sealant take it? Now instead of a 1/32-1/64 thick layer, there's is a 1/4" layer: 8-16x the amount of force from crankcase pressure/the weight of the oil, but still has the same cross section that it can grab the metal with.

    Any ideas other than RTV black? Softer with more elasticity means even more reduction in vibration transfer...

    Put weights on oilpan? (To increase the amount of force required to vibrate it, and therefore cause the RTV to flex/compress instead)-same effect as a softer, more elastic material.

    Vehicle is a 2000 Isuzu NPR with a 4.8L I4. Figured it was most similar to the 4bts which a lot of people have noise issues with.
    Also, I won't be able to do this until my next oil change which is in 5-6 months with my usual mileage.

    After though: no idea what torque to tighten them to, maybe just do a distance measurement: from 1/4" of cured RTV to 3/16" when tightened down, and use threadlocker blue when installing.
    (once the washer is attached via the 1/4" of cured RTV, the bolt could be removed and threadlocker applied)


    Other cons,
    Lose your vehicle for a while (put 1/4" RTV on oil pan and half of the washers, (while other half of the bolts hold the pan at right distance during curing), then do other half of bolts and cure for a full 24 hours (using it as a damping element, not just a sealant so I would want full strength)


    Edited for grammar and instructions making more sense
     
  2. 79jasper

    79jasper Chickenhawk

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    Just get some spray on bedliner and go to town.
    Obviously clean it first with brake kleen.

    Sent from my SAMSUNG-SM-G935A using Tapatalk
     
  3. Woofythewolf

    Woofythewolf Registered User

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    I had previously tried plasti-dip (put on 10 coats) with meh results (I can tell there is a tone difference, but not much and still too high for my decibel meter)

    Is Bedliner softer?(I don't believe so) Or is plasti-dip too soft and therefore not doing It very well?
     
  4. 79jasper

    79jasper Chickenhawk

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    Roll on bedliner has chunks of rubber in it.
    Plasti dip is probably too soft.

    Sent from my SAMSUNG-SM-G935A using Tapatalk
     
  5. SebastIDIan

    SebastIDIan Full Access Member

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    Gasket shaped dynamat layers with holes in it for the bolts
     

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