03 Detroit 60 series 12.7 Jakes rattle like metal on metal? like hammer inside?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Freightshaker03, Apr 12, 2021.

  1. Freightshaker03

    Freightshaker03 Bobtail Member

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    Recently purchased a 2003 freightliner Classic with the Detroit 60 12.7l
    It has twin stacks (5") with standard mufflers.
    Is it normal for it to sound like a huge wrench is banging the inside of the stacks when the jakes are turned on?? Its so loud! Its like a rap rap rap rap!! but so metallic sounding it scares me! It kind of sounds like it goes along with one cylinder rather than evenly if that makes any sense?
    I can maybe upload a video if I can figure out how...
    Just wondering if its normal for these engines to be clanky!?
     
    AModelCat and Rideandrepair Thank this.
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  3. Rideandrepair

    Rideandrepair Road Train Member

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    Muffler baffles are rusted out.
     
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  4. Freightshaker03

    Freightshaker03 Bobtail Member

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    I actually just replaced both mufflers because that’s what I thought! But it’s still the same...:(
     
  5. Rideandrepair

    Rideandrepair Road Train Member

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    Yikes!! How about the Y pipe? Usually crack at the weld.
     
  6. Freightshaker03

    Freightshaker03 Bobtail Member

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    Oh really? I thought it looked good at a glance but I’ll check again tomorrow! I really hope it’s just something like that. Because it’s really annoying! Does anyone on here own one? If so does it sound like this? Someone I know said they thought it might be normal... so I’m confused.
     
    Rideandrepair Thanks this.
  7. Rideandrepair

    Rideandrepair Road Train Member

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    I’ve got an 01, had a 99. Been running Classics since 2000. My 99, when almost new, had a quiet muffled sound. I put flo thru’s on this one, it’s a little rattly, but not real bad. Any chance some of the old baffles inside the y pipe? Common leaks are also at bottom of elbows. Any leak is easily felt by placing your hand near it. Had a DOT once go straight for my elbows, said he always finds a leak on Classics. Lol.
     
  8. Freightshaker03

    Freightshaker03 Bobtail Member

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    Hmm interesting thought.. but I’m pretty sure I didn’t see anything in there.. I may pop off an elbow and take a look! It sure sounds like something is rattling in there.
    Would you know how much boost I should get while jakeing down a grade with a loaded tridem? I get a maximum of 20 psi. And it runs away very fast so I have to keep using the brakes. Meanwhile it raps away making me deaf and waking up everyone within a few miles! Lol
     
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  9. Rideandrepair

    Rideandrepair Road Train Member

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    I’ve never paid attention to boost with the jakes on. I will now though!! Maybe they need to be adjusted. Part of an overhead. They also have rebuild kits for them, very inexpensive. I’ve never rebuilt my current ones. They have over 2 million miles on them. As long as they come on and off when switched, I’m happy. The jakes aren’t that strong, mine runs away easily. I would just check all the exhaust connections for leaks, especially the flex pipe, feeling for air, and looking for black soot. Only other thing I can think of is a possible vibration from exhaust hitting something. Maybe only hits while jakes are on, with engine torquing in different direction than when accelerating. I highly doubt it though.
     
  10. Freightshaker03

    Freightshaker03 Bobtail Member

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    Oh wow! That’s a lot of miles!
    I’m thinking maybe the exhaust it subbing on the frame a little under the cab? Maybe that’s what’s doing it? I’ll try to make it farther away from the frame and see if that helps!
    I actually had an overhead done on it before I started running it. So it should be good. Unless they messed something up.
    I’ll have to go over The exhaust again and see what I can find!
    Thanks
     
    Rideandrepair Thanks this.
  11. Rideandrepair

    Rideandrepair Road Train Member

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    I think you’re 03 has the improved cab ride. Lots of room. Good idea, check it out. May even be a heat shield rattling.
     
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