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Caterpillar 3412 HEUI injectors

Discussion in 'Other Earthmoving Equipment' started by excavator, Oct 15, 2013.

  1. excavator

    excavator Senior Member

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    On the early 3412 HEUI motors, the original injectors are no longer available. I've been told that the new style injectors have a check valve in the oil return line so that the oil will not run out, resulting in hard starting after setting for a week or two. Is there any other way to solve this problem,besides replacing all the injectors? With the cost of new injectors, changing out all 12 is quite cost prohibitive, but this motor, after setting for a week or two, will not start at 40 degrees and this is what Cat says needs to be done. Any ideas?
     
  2. rare ss

    rare ss Senior Member

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    I've heard that a can of aerostart was the weapon of choice for the cost savy maintenance
     
  3. CAT793

    CAT793 Well-Known Member

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    Non-Prime Squirters were the ONLY good thing about a HEUI....don't rob yourself of that!
     
  4. Nige

    Nige Senior Member

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    What model of machine is this engine installed in and what Part Number of injector do you have installed right now..?
    Also how many hours do the injectors have on them..?

    The only difference I am aware of between the 2 types of HEUI injector is that the early design (Prime-type) injected fuel in 2 separate stages, the later ones (Non-Prime type) injected all the fuel in one hit. I have heard nothing regarding about an internal check valve being added.

    The change of injector from Prime to non-Prime was made about the 2003 time frame. I find it hard to believe that any Prime-type injectors would still be in an engine 10 years later, they didn't last that long......... 10 months would be more likely....!!
     
  5. CAT793

    CAT793 Well-Known Member

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    Remove the Tappet covers and watch the Engine start COLD. Soon work out which Squirter type you have.
     
  6. Nige

    Nige Senior Member

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    Better still, remove the tappet covers and read the Part Number off the injector ........ :tong
     
  7. trackdoc

    trackdoc Well-Known Member

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    No matter what type of injector you fit, starting is still an issue after a long lay up.
    Especially if the engine application means the engine sits high at the front ie marine.
    The best and cheapest cure for this is to fit a pre lube pump.
     
  8. Nige

    Nige Senior Member

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    A prelub pump won't make a ha'porth of difference on a HEUI. If during cranking the hydraulic pressure in the system (Actual Injection Actuation Pressure) does not get up to the value that the ECM wants (Desired Injection Actuation Pressure) then the electronics will sulk and refuse to play. Result is no smoke from the chimney and no start. Oh how I thank my lucky stars I don't have to work with 3400 HEUI engines any more ..........
     
  9. trackdoc

    trackdoc Well-Known Member

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    A prelube will fill the HEUI pump with oil before cranking.
    We have had good results with this in marine applications where the engines sit high at the nose and the oil drains away from the HEUI pump very quickly.
    The first time we came accross this issue was in a Life boat, CAT sent me out to tell the customer he had to remove the oil line leaving the pump and pour oil in to prime the pump and start the engine.
    As you can imagine the customer was not happy with this advice.
     
  10. Nige

    Nige Senior Member

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    I can only comment on machine engines but the prelub pump seemed to make no difference whatsoever to cold starting performance. The added difficulty was that due to the lack of space the prelub pump was integral with the starter motor and burned up with monotonous regularity.
     
  11. excavator

    excavator Senior Member

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    This engine is in a Morbark tub grinder, not sure of the year. I may be in the area tomorrow and will try to check the engine numbers. I was considering whether a prelube pump would work. When cold and having not run in a few weeks, this thing will crank out the smoke but even with a bit of aerosol assistance it will not run until the outside temp rises. Once started it runs fine.
     
  12. Gavin84w

    Gavin84w Senior Member

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    Tub grinder hey, check the tubgrinder hydraulics are not loading the engine prior to it starting, have seen auxillary applications like this where there is a slight hyd load on the pumps which cause the cranking speed to be off by a bit which then inturn don,t allow it to fire.
     
  13. trackdoc

    trackdoc Well-Known Member

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    Try manually filling the HEUI pump with oil.
    If this works, the prelube will help.
    For sure if there is any sort of load on the engine it will struggle.
    How many starter motors are on the engine ?
    We find they need 2 for the winter.
     
  14. Nige

    Nige Senior Member

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    We had major issues with HEUI engines in the Andes. A combination of 10,000ft+ altitude and temperatures low enough to freeze the nuts off a polar bear meant they were very reluctant to come out and play starting from stone cold. As other posters have mentioned the key is often the engine cranking speed. If you can get to 150 RPM on the starter motor there's a good chance that the engine will fire up. However even at high RPM on the starter excessive leakage at the injector poppet valves is your enemy. If the leakage from the 12 injectors is more than the HEUI pump can supply the rail pressure will never get high enough for the electronics to come out and play and the engine will never fire.

    Excavator - get the engine Serial Number if you can. Also if you've got mechanics on site pull one of the valve covers and read the Part Number off the injectors. It will need a small mirror to do this because the number is hidden down the side.

    Another clue - if it's smoking out of the chimney then the electronics are playing and you are getting fuel. That means the HEUI system is getting enough pressure to activate the electronics. I would hazard a guess that your problem is not necessarily the HEUI Pump or the injectors. Maybe an external parasitic load when cranking as others have suggested.
     
  15. John C.

    John C. Senior Member

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    How many hours are on this engine? The usual issue I've seen on tub grinders is constant overload, violated air filters and the big potential of overheating makes for loss of compression into the crankcase. As Nige says "if it's smoking out the chimney then the electronics are playing". Take a look at the ends of the breather tubes and if they are covered in lots of oily dirt your problems may be only just getting started.
     
  16. skara2007

    skara2007 Member

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    Hello! I'm a new member and am desperet for some answers. so please if you know , HELP. I have a 3412E 4CR engine 980Hp. The injectors are falty. now as they are wery expencive I wass lucky to find the reman injectors at wery afordable price. The original injector number is 174-7529, and the reman ones are 174-7526.
    My question is: what might bee the diference between them and will they work on my engine. Please help.
     
  17. Nige

    Nige Senior Member

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    174-7526 Part Number of HEUI injector is for a 3400E machine engine, not an industrial engine like you have. These injectors will not work in your engine as far as I know. 174-7529 (replaced by 174-7528) is the correct Part Number for your engine.

    Also my experience is that Caterpillar gave up trying to remanufacture HEUI injectors many years ago because of the failure rate on Reman injectors. I would be very suspicious of any aftermarket provider that is suggesting they can successfully remanufacture HEUI injectors.
     
  18. skara2007

    skara2007 Member

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    These ara cat reman. the number 174-7528 does not aplie with this engine. When you say it wil not work , do you meeen that it want start at all or??
    what is the main diference betwene the two injectors, couse they look exsactly the same from the outside. The thing I know 100% is that the hydraulic part of the injectors is the problem in my case. I have disasembled them number of times and the nozle part is ok. the problem is in the hydraulic valve and the internal seal of the intensifier piston. my question is the hydraulic part the same on both injectors. my idea is to put my nozles on the new injectors. what is your opinion on that. the price of naw injectors is uncomparable with the ones i can get. that is why I'm wilng to try this. tel me what you think please. Thanks for the first replie and sory if the speling is bad.
     
  19. Nige

    Nige Senior Member

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    If they are genuine Cat injectors then they are actually brand-new despite the fact that it may say "Reman" on the box. Also the Part Number on the injector would be 0R-xxxx or 10R-xxxx if it was Reman. The Part Number you mentioned in your post is a new Part Number not a Reman one.

    You'll note that I said "Cat gave up trying to remanufacture" HEUI injectors, not "gave up selling remanufactured injectors". A Cat dealer will still take your old injectors as cores against Reman injectors. However instead of the cores being shipped back to Cat's Reman facility for rebuilding they simply get junked.

    In the Parts Book for 4RC it gives the Part Number of 174-7529. However when I look at the Cat Parts system for price and availability of 174-7529 the information appears that it has been cancelled and replaced in the system by Part Number 174-7528 - that is the current Part Number for your engine even though your Parts Book may say 174-7529.

    Although they may look the same there will be major differences in fuel delivery and fuel injection timing between the 2 Part Numbers. I'm not saying that they will not work (the engine will definitely run, no doubt about that), simply that they are not the correct injector for your engine and may produce undesirable results when installed. Your idea of putting your existing nozzles on the new injectors may work, but again I have no information regarding what adverse results you might experience.
     
  20. skara2007

    skara2007 Member

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    thanks for the answers. I have a CAT sis 2009. maybee that's why I cant find 174-7528. Buth allso i cant find it anywhere else on the net. I'm gona give it a try and see what hapendes. By my expirienca the bigest fault in dhese injectors are the internal ruber seals. If a bad oil is used in the engine afer some time the ruber stics to a intensifier piston, after that if an engine lays for a couple of days, it is inposible to start couse the actuation presure cant move the intensifier until the engine starts warming up. usualy my engine starts on 3 cylinders after a 3-5 mins of ether. than after 30-40 minutes it runs smooth and with no problems.