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3126 cat blowing up fuel primer pumps and losing hpop pressure

Discussion in 'Trucks' started by walkerv, Mar 14, 2019.

  1. walkerv

    walkerv Senior Member

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    Anyone seen this happen repeatedly before im very familiar with the fuel system and the only thing we havent changed is injectors , i have 6 new ones in the truck along with another check valve fitting that goes in the back of the head , and a spare huei pump just in case, talken to the truck engine guys at cat they are baffled as well .
     
  2. thepumpguysc

    thepumpguysc Senior Member

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    wow.. I have to say I haven't either.. IF its the injectors, the return must be out of this world & would cause all sorts of running issues..? of something is hooked up "backwards".??
     
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  3. Truck Shop

    Truck Shop Senior Member

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    Filter head? Totally bizarre issue, like above return must be super high.
     
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  4. walkerv

    walkerv Senior Member

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    It just started doing it , first thing i changed was fitting in back of head it was stuck, but then i still didnt have oil pressure to fire injectors , changed hpop pump yruck fired rite up all was fine , not sure how long they used it but i guess i shoulda done some hotlaps in this big field im in .just got to it gonna hook up laptop and see what high pressure pump is doing, then im going to pull valve cover and see if sone injectors are dumping exxessive oil i have a theory but its only a theory at this point .
     
  5. walkerv

    walkerv Senior Member

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    276 psi huei pressure valve cover coming off
     
  6. walkerv

    walkerv Senior Member

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    Nope return is still fine i think it lost another hpop pump due to the engine dieing a slow death, the engine oil will jump to my magnet. Gotta discuss options with the boss man once he makes his way into this field. I may be able to make it last thru the manure spreading season but is gonna be a huge expensive gamble
     
  7. walkerv

    walkerv Senior Member

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    200 pound gorrilla got the last pump he was a little to mean pumping it , i got the paul harvey version a minute ago , but the true start of the problem i will take a picture of and post in a little bit
     
  8. walkerv

    walkerv Senior Member

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    Root cause in t 20190315_105233.jpg he picture
     
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  9. walkerv

    walkerv Senior Member

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    Ok here is the final rundown start to finish and what i found .it will be a long read.
    Trip 1 boss man changed blown up primer pump
    Trip 2 me , no power low power , found icp pressure sensor failing and possible ipr valve bad. Changed pressure sensor ,yep low pressure wouldnt go over 1750psi , changed ipr valve truck wakes up and runs good makes full pressure using cat et actuation test.
    Next day phone call 1 blew up primer pump again, we left them a spare so they changed it but now a no start.
    Trip 3 , me , first tackle fuel issue cant pump primer, remove dog box ( I HATE WORKING ON GMC MEDIUM DUTY TRUCKS),, Remove fitting in back of head try primer pumps fine ,see no debris in fitting must be stuck, install new fitting and hook line back up , retry primer it is now fine pumps fuel normaly. Tackle the no start huei pump making 257psi that wont work, thought high fuel pressure issues may have damaged huei pump inside changed huei pump truck started ran fine.
    Phone call 2 next day truck quit again same field only made 2 rounds spreading chicken litter ,I was told primer came apart again i was like fml at this point they had a spare again so they changed it but still a no start.
    Trip 4 me , talk to guy running truck he broke primer this time pulled it apart told him not to touch it that is not the problem with the teuxk quiting.
    I had a theory but kept quite good thing cuz i was way off.
    Step one for today double check fuel primer issue hook up pressure guage all is fine there. Hook up ET this time 280 psi all i getting out of huei pump, talk to cat they said check for a dumping injector and cut open oil filter. No oil coming thru injectors wondering if one has a cut o ring and its going into fuel, of course i cant tell in a fuel tank of red fuel. Cut open oil filter no aluminum chuncks from huei pump but metal is gray and sparkly , drained oil looked like i was draining an old differential, got a hand full of oil and found it has so much metal in it that it would jump up to my magnet, at this point i already new about the broken air filter housing but no one has any idea how long its been like that , get boss man he is willing to make the gamble so i proceed.
    Pull injectors to check out o ring situation they were ok but ended up putting the new injectors in . Pulled high pressure oil galley plug at back of head and let drain and rinsed out with brakeclean best as possible . Installed new oil filter washed bottom of pan out with half a gallon of fresh oil and refilled , left galley plug out and cranked engine untill cleanish oil came from huei pump, buttoned everything up properly reprimed fuel and oil systems and topped off oil , check high pressure on crank still 280psi, removed ipr valve sprayed and blew out several times. Reinstalled cranked for about 5 seconds bam pressure went up to 1450 , tiny shot of ether got this worn out low on compression kitty cat going on a 75 degree day.
    In conclusion i think i figured out the low oil pressure was due to the highly magnetic oil messing with the ipr valve especially in its higher duty cycle when they are spreading **** esentially clogging it up from the magnetism of the solenoid , there was that much iron in the oil.
    They wouldnt let me leave till it made 4 trips into the field , i told them to dump the oil again after it warms up and i would look at a one of our sources for a good used engine, they only need it for 2 more days then it will come back to home farm but i am going to see if they will just bring it to the shop at the grading company instead so its near my stuff. So in conclusion i fixxed it but i didnt , its a wore out turd with a little fresh lipstick needing a transplant badly, new air filter housing is ordered so it will be good when it gets fixxed . Dang i should have done this on my computer not my phone, ohwell have a good one yall.
     
  10. Wes J

    Wes J Senior Member

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    Jeepers. Sounds like fun. I like your theory on the IPR. If it's like the International version, you can buy a service kit with a new screen filter. It's a bit ridiculous that all of the HPOP oil goes through that tiny screen. You'd think they could put some kind of real filter in there.

    I'm not sure I understand all of the issues with the primer pump. Was that an injector issue?
     
  11. walkerv

    walkerv Senior Member

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    The first of the primer pump issues was due to a stuck restrictor fitting in the back of the head ,apparantly the primer pump is weaker then the fuel filter below it . The rest of the primer pump issues was operater error and pulled it apart aka 200 pound gorrilla . The icp valve looks identical to IH icp valve but no screens, which frankly wouldnt have helped as the oil looked like it came out of a really old differential all very very fine metal looked like grey sludge on the drain plug.
    Cat has a filter kit you can put on the c7 im sure they have it for the 3126 also but i have yet to see one installed on an engine, it has a replacable element.
     
  12. Nige

    Nige Senior Member

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  13. walkerv

    walkerv Senior Member

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    Yeah i probably could fit it no problem to the 3126 firstly though i need to see if big boss man is alright with me finding a good used donor, im almost positive all the iron in the oil is cylinder wall and piston rings from sucking field dirt and manure dust, i can only imagine what the inside of this engine looks like rite now , it starts hard at 75 f and you can hear it sounds like it already has a hole about wiped out when cranking . It only has to last 3 more days total unless they want to use it on the home fields also , if so it will get another service and its new air filter housing along with all intake piping and charge air cooler washed out. Then it will be parked for the summer .
     
  14. kshansen

    kshansen Senior Member

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    Hope the big boss man isn't like some of the ones where I worked. Don't work on it now we need it, then don't work on it now as we won't need it till spring, next winter or whatever!
     
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  15. walkerv

    walkerv Senior Member

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    Hard sayyen hope not even though its on the farm side of things, i would like to at least have a good runner sitting here if they decide to run it till it wont.
     
  16. Wes J

    Wes J Senior Member

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    I'm thinking those engines don't have liners, parent bore. But they made a lot of them so a used one shouldn't be too hard to find.
     
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  17. Birken Vogt

    Birken Vogt Charter Member

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    Seems like they all have similar problems though, especially as they get old.
     
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  18. walkerv

    walkerv Senior Member

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    Got a new to us used pull out from a sterling coming to us this week . Truck will be back from southern farm this week , we are gonna use it spreading at the home farms as long as it will stay running then it will get parked at shop and i will work on it thru the summer months in between dump truck problems . When i first looked Dex had 23 cat 3126 engines yesterday i looked again they had 12 by the time i found boss man they had 11 we picked out a runner for 3k aparently they are a hot mover.