New CAT Air compressor Locked up?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Don379, Jan 27, 2022.

  1. Don379

    Don379 Heavy Load Member

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    Motor is Cat C12 serial prefix 2ks
    I Swapped out my bendix unit and put a Cat reman unit in that peterbilt ordered for me about 2 weeks ago.
    Was a simple swap and have had the truck running with it For a few days. I have been doing alot of stuff to the truck including, just got done swapping radiator and cac and hood bushings. Truck is a 379. So today pullled truck in front of barn and did a bunch more preventative stuff. When done, i start truck up and proceed to drive my truck down my lane to go park it for the night, when i hear all kinds of racket coming from motor. Im like wtf now. So any how, im like i dont care at this point if motor coming apart. Just spent 30 hours past few weeks doing work on it.
    I kept truck running and tried to investigate. The noise is coming from front cover. Im thinking it cant be air compressor, SO i bleed air psi down and sure enough, its not building back up. I yanked the oil fill spout off the side of the block to get a visual. When you pull the oil fill, you can see the air compressor gear clear as day. When i did that, there was all kinds of metal on the spout. A gear came apart. I start truck again and look, the compressor wheel isnt turning at all SO i think the teeth sheered off but you can see the cam gear is. Im pretty sure the cam gear turns the Air compressor. I shut the truck down and try and turn the compressor gear with a pry bar and it wont even budge. I may have to pull the dam hood and radiator again and pull front cover but maybe its just the compressor gear that came apart. IS this unheard of for a new cat reman to lock up. Thoughts anyone? @Goodysnap
     
    Last edited: Jan 27, 2022
    Crude Truckin' Thanks this.
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  3. Goodysnap

    Goodysnap Road Train Member

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    Did you transfer the compressor gear from the old to new compressor?

    Why did you replace? Something has changed. Oil line supply line free and not kinked?
     
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  4. BoxCarKidd

    BoxCarKidd Road Train Member

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    No I never heard of that. Had a C15 here with the Cat compressor replaced with a Cat. No one knows if the guy tried bumping the starter trying to get it in. Used bolts to try to pull in or what. Best I recall it had three bolts and a plate in front of the gear. Maybe the gear was not on the compressor correctly. It ate a hole in the front cover. A bit of a gray area but go back to the last work that was done. Pull the compressor.
     
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  5. AModelCat

    AModelCat Road Train Member

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    Definitely pull the compressor off and try to figure out why it locked up.

    Hopefully there's no other gear train damage.
     
  6. Don379

    Don379 Heavy Load Member

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    ok. i will pull the compressor in the morning and report back with pictures for you guys then tomorrow night
     
  7. Don379

    Don379 Heavy Load Member

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    i replaced the old unit just becuase i was doing preventative maintaanence and have the money and time right now. I swapped the gear on to the new unit. Also replaced the oil feed line with brand new feed line from cat. NEw coolant lines as well. So definately no kings. The old oil feed line was trashed. The old pump had some sort of sleev/ collar or spacer that goes on before the gear also. Not sure what it is called but i swapped that on to the new unit. The old unit was a bendix tu flo 750. The new unit is CAT tu flo 750. Id imagine basically same thing, but the cAt rebuild unit is about 500 more bucks. Shame on me for thinking cat was better
     
  8. rogermunn1

    rogermunn1 Light Load Member

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    Is that collar a shim to move the gear out farther . Maybe the new compressor didnt need it and it put too much force on engagement . I always put a straight edge on the mounting flange of anything and measure depth to get an idea of clearance . Had gear stuff fly apart before and cost me money so i take the extra time now always
     
  9. Don379

    Don379 Heavy Load Member

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    dont know how to explain it. Freak accident. The bolt sheered off the snout that holds the gear on to the air compressor. I think it may have been cracked or possibly me that over torqued it. I always, let me repeat, ALWAYS use a torque wrench. In this situation, it was 15 degrees out and i was in a hurry and gave it a 3 second rap with 1/2 air gun and called it good. I cant claim warranty with this.
    Thats not the bad part although it still doesn't bother me. IT is what it is. The crank shaft on the compressor got bend up from the bolt trying to go under the sprocket. When that happened, it locked the compressor, At same time, severely damaged and removed teeth off the idler. Also made a major mess of the cam gear. When i removed the compressor, i could see the mess this made. Th truck DID NOT skip timing. IT runs and starts fine. So that tells me that the timing gears did not skip. However, they do need replaced. I wanted to start truck after pulling comressor to see if the gear rattle and noise was gone. Why? BEcuase that would tellme that no other snouts got bent. I removed secondary fuel filter to have more clearance and it was snowing its butt off on me and just wanted to go get warm after removing compressor. So i have alot of workto do NExt wek. Gotta pull hood and radiator and front cover. My tech manual is telling me to pull the cam to get the gear off. I have a 12 ton hydraulic gear puller on te way. So i don think ill be pulling cam. I can do that to but gonna try the puller first. If that dont work, ill throw oxy and aceteylene at it and it should pull off. I have yet to see what else i will need when i pul front cover. Each gear is about 1 thousan bucks from at, but i already fund each gear for under 200 bucks off salvaged parts websites.Sorry didnt take pictues. like i said it was snowing on me
    @Goodysnap
     
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  10. Don379

    Don379 Heavy Load Member

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    i might be replacing the idler n the passenger side as well as sprocket on crank. Wont know until i rip her apart Not costing me downtime. I decided to take the winter off.
     
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