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sounds like I have a "jake brake"??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by MudNurI, Jun 4, 2002.

  1. MudNurI

    MudNurI 1/2 ton status

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    sounds like I have a \"jake brake\"??

    Seems the k5 is trying to sound more like my D/A every day.

    while driving in 4th gear- somewhere around 45-55 mph when I let off the gas- not completely, but 1/2 way I'd say, like the car in front of me slows down,,,etc... I get this horrid jake brake noise. When I completely let off, it stops, and when I go back to full throttle it stops, however if I hold it at 1/2 throttle, it continues. It's a nasty sounding noise, and is quite loud..though it may not be loud, if I had some sort of floor covering.

    it only does it in 4th gear, at the above speeds. could this be something in my transmission ? It's not a whine, and doens't sound like a bad u-joint, its more of a deep growl, very similar to a jake brake.

    can someone point me in the direction to begin? Thanks guys! your the best

    Brandy
     
  2. Sandman

    Sandman 3/4 ton status Author

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    Re: sounds like I have a \"jake brake\"??

    What kind of mufflers are you running? Glass packs will do that if your running rich.
     
  3. shane74

    shane74 1/2 ton status

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    Re: sounds like I have a \"jake brake\"??

    There are a couple of things that could cause that. The first and easiest is to check your driveshaft. Make sure it is lined up right. Meaning that the shaft is in the right position with the yoke. There should be a dot or other mark stamped into the yoke and the shaft. If those are not lined up, you'll get a bad noise and vibe problem. Contrary to poular belief, the splines in a shaft and yoke are not perfectly round (hence the balancing weights welded onto them). If the shaft and yoke are "out of round" to the original balance, then you'll have the shaft out of balance and tearing itself up. It is very easy to mis align a shaft and yoke after replacing the u-joints. ALso, the vibration caused by this may be very minor and hard to notice especially if you are running over sized tires and lift. You usually expect some vibe when you run bigger tires and lift. Check the shaft to yoke alignment if that is good, then....

    The next easiest thing is to replace the top u-joint at the t-case. I experienced the same type of problem and it was the u-joint at the t-case. If you have recently replaced them, then move on to the.......

    Worst case scenario of your yoke/shaft wearing out and you are feeling the play because at that particular rpm range, there is enough free play to let the parts slop around and slam into each other. When it gets real bad, the noise and vibration will be there all the time. Try swapping in a different driveline if you have access to one and see what happens. If it goes away, then you know it's your shaft.

    Hows that for the long version of a short story?!
     

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