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Thread: Cat d4 7u smoking and popping louder now

  1. #1
    Join Date
    Dec 2019
    Location
    Columbus, ms 39701
    Posts
    32

    Default Cat d4 7u smoking and popping louder now

    Ok, so I've got another question about my 53 model d4 7u. When I bought it about a month ago, it would crank but smoked gray smoke at startup and while running except at full throttle. At full throttle the smoking would stop and seemed very smooth. Well after running it a little, it still smokes but I did notice that cracking the #2 injector would make it smooth out and no smoke. My book says to change out that injector nozzle to clear that up - I did. Seems harder to crank now, smokes probably more than it did, and pops a good bit even at full throttle. I didnt ever drain the fuel out and figure theres water in there but what's up with it smoking and making more racket now? I'm not a full blown mechanic and hope this is not a hard fix if anyone can help with advice? Thanks!

  2. #2
    Join Date
    Nov 2006
    Location
    Faunsdale, AL USA
    Posts
    4,129

    Default

    If the #2 pump is not installed with the marked tooth of the plunger gear quadrant aligned properly with the line on the rack, you will get some obnoxious popping. Itís easy to check. Just take side cover off injection pump housing and look in with a bright light. You should be able to compare each pump to the others and quickly see if one is mis-timed.
    D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time

  3. #3
    Join Date
    Dec 2019
    Location
    Columbus, ms 39701
    Posts
    32

    Default

    Quote Originally Posted by ccjersey View Post
    If the #2 pump is not installed with the marked tooth of the plunger gear quadrant aligned properly with the line on the rack, you will get some obnoxious popping. Itís easy to check. Just take side cover off injection pump housing and look in with a bright light. You should be able to compare each pump to the others and quickly see if one is mis-timed.
    I dont think the pumps have ever been changed on it but I'll check that. I'm just trying to figure how it got worse after I changed the nozzle. Perhaps that was already out of time and I made it worse by it actually getting fuel now. The old nozzle was rusted up badly!

  4. #4
    Join Date
    Nov 2006
    Location
    Minnesota
    Posts
    498

    Default

    Exhaust valve stuck open?

  5. #5
    Join Date
    Dec 2019
    Location
    Columbus, ms 39701
    Posts
    32

    Default

    Could be I guess - how would I check that?

  6. #6
    Join Date
    Nov 2006
    Location
    Minnesota
    Posts
    498

    Default

    Pull valve cover and look at the #2 exhaust valve. Is it coming up the same height as the others? Is there any clearance between the rocker arm and valve stem when valve is closed? Listen for a hiss in the exhaust pipe while turning over by hand.

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