6.2 rattle

Discussion in '1982-Present GM Diesel' started by sreidmx, Feb 14, 2017.

  1. sreidmx

    sreidmx Fortify Offroad Vendor

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    So last night I finished replacing the last of my return lines with good doorman lines, the badger diesel version I purchased were junk and wasted a lot of time.. never again!
    Seeing that it idles normally now I can hear a rattle from the front of the engine, I laid under the truck for a while trying to see where it was located and I deduced that it has to be my timing chain, one thing I noticed that the engine speed would change ever so slightly as I could hear the rattle. It is somewhat inconsistent and may not be possible to catch on video because of the normal diesel clatter.
    To me it seems rather obvious that it's likely a chain that is stretched?? By the way the water pump is new..
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Sounds likely, there isn't much else that could rattle in that area...
     
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  3. sreidmx

    sreidmx Fortify Offroad Vendor

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    Maybe someone left a box of marbles in there?
     
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  4. Mark Leisenfelder

    Mark Leisenfelder 1/2 ton status

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    does it go away when cold? where is your timing set? do you still have the check valve that screws into the IP for the return line.
     
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  5. sreidmx

    sreidmx Fortify Offroad Vendor

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    I'm not sure what the ip timing is but I cannot advance it any farther because it's physically stopping, it does not change with temp at all it is apparent cold or hot.
    I'm not sure about the check valve as I haven't had the return line off yet.
     
  6. campfire

    campfire Adventure is out there! Premium Member

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    This seems like the most likely option.

    You know that GM left a small bag of marbles inside each 6.2 engine as a noise enhancement, right? It was the best they could do back before electronics entered the picture.
     
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  7. sreidmx

    sreidmx Fortify Offroad Vendor

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    Makes total sense since you put it that way..
     
  8. diesel4me

    diesel4me 1 ton status Premium Member

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    A long shot--it could be the lift pump...

    I had a fuel pump on a 350 lose the little spring on the rocker arm that operates the diaphram,and it let it "clack-clack-clack" intermittently ,most noticeable at idle..

    I almost replaced the timing chain & gears ,thinking the chain was slapping around--but closer inspection with a sounding bar to my ear on the fuel pump pinpointed that as the noise source,and clamping off the fuel hose going to the carb silenced the noise temporarily..

    After I put a new fuel pump on ,no more noises...later on in that engines life I decided to replace the chain & gears anyway,seeing I had them,and didn't want to risk having an oem nylon cam sprocket failing somewhere far away...but when I got the cover off,I found a nice Cloyes double roller chain & gears,that was still tight..:doah:.had a battle getting the harmonic balancer off too!..

    The 6.2 in my pickup sounds a lot like my clothes dryer when I'm drying a load of pants with metal zippers--sometimes more like a pair of sneakers ...hard to tell when a 6.2 is going to throw a rod,when it sounds like one is trying to come out since day one..:eek:..
     
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  9. sreidmx

    sreidmx Fortify Offroad Vendor

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    Ok I actually was considering putting an electric pump on it so that'll be an easy swap to get rid of the lift pump.. maybe I'll get lucky and that'll be it..
     
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  10. Vombrown

    Vombrown Mountain Man Premium Member

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    The timing chain would need to be very loose to make enough noise to be heard over the engine running. If the rattle is more of a tick i would be looking at that injector pump. Another trick is to listen with someone mashing the accelerator. If it is a timing chain the sound should go away with increased rpm as tube chain speeds up.
     
  11. diesel4me

    diesel4me 1 ton status Premium Member

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    Some 6.2's had that funky 2 peice harmonic balancer pulley with a rubber insert--those can get noisy after the rubber wears or chunks come off after many miles...

    After listening to many 6.2 videos on Youtube,I guess mine sounds "normal" even though to me it sounds like it wants to come apart--especially on cold days after a cold start!..:eek:..
     
  12. campfire

    campfire Adventure is out there! Premium Member

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    Are you talking about the 2-piece flywheel that was used on some of the 6.5 engines? I don't think the 6.2s got those, and it wasn't long before GM ditched that idea entirely.
     
  13. diesel4me

    diesel4me 1 ton status Premium Member

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    No,the harmonic balancer--I have one of the goofy 2 piece ones on my '87 parts engine that broke the crank,I'm not sure it looks exactly like this one I found on google images,might be more than one type out there...if it wasn't 15 degrees out I'd go take a picture of it!..

    I think "Massboy" here on CK5 had a write up about replacing this type of damper on his Blazer a few years back.. 6.2 diese 2 piece balancer.jpg
     
  14. campfire

    campfire Adventure is out there! Premium Member

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    2 pieces...as in a pulley and a damper? Looks standard to me. Was there another OEM alternative? Fluidampr doesn't count.
     
  15. diesel4me

    diesel4me 1 ton status Premium Member

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    There is a "solid" damper that looks much like any typical gas one too--I think GM went with the goofy 2 piece type to reduce V-belt "flapping" and the noise transmission...however I think the '87 parts engine I have was a serpentine setup,I will have to look closer at it,I might be wrong..
     
  16. campfire

    campfire Adventure is out there! Premium Member

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    Please do, I am now curious. Our 1993 6.5 has the same style that you posted earlier.

    I remember Massboy, his thread went dead after he finished the build. I think he went the Fluidampr route, but I'm not completely sure.
     
  17. diesel4me

    diesel4me 1 ton status Premium Member

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    I think he posted he found an OEM new balancer for his 6.2...the 2 piece type...
     
  18. longbedder

    longbedder 1/2 ton status Premium Member

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    My bet would be the damper (no matter which configuration). If the rubber is shot, there will be metal-on-metal contact - there are hard-stop tabs to keep the outer ring from spinning completely off (the radial arms hit the bolts).

    If you're out of adjustment on your IP and the timing is not correct, replacing the chain will fix that. I have a timing light adapter I'd be happy to mail you and let you borrow if you want to check actual timing (light sensing type, not pulse sensing type).
     
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  19. diesel4me

    diesel4me 1 ton status Premium Member

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  20. GWeakland620

    GWeakland620 THE CK5 Crayon Eater Premium Member GMOTM Winner

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    I like learning about these things. Something calming about them. Not sure why.
     
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