Thermo king apu

Discussion in 'Ask An Owner Operator' started by pavrom, Feb 17, 2024.

  1. Arctic_fox

    Arctic_fox Experienced mx13 execrator

    Sep 16, 2016
    Using my old one as an example, head gaskets, fuel pump, water pump, check computer condition as the wires tend to corrode as well as the main circut board on the ECM, the belt is likely shot, check the rollers, the air intake likes to crack with age so check that, get an oil sample to check for metal in the oil. Function test all the sensors especially the oil pressure ones and the high low ones as they fail....constantly. honestly id just replace all the sensors as its cheap if you do it yourself.

    replace and/or clean all fuel lines and inputs, check glow plugs as they like to foul up and likely need to be pulled and cleaned at a minimum. Replace dampers as the ones thermo uses are usually low grade cheap garbage, check for leaks around the block as it can indicate a number of issues, the cooling fan on those always fails so have it, the motor and the wireing just will thank me later.

    If its a stand alone unit, just yeet the radator it comes with as they are highly unreliable, if its a loop with main truck engine system replace all hoses and run a clean brush through them to check for nitrate buildup. Also install a cutoff valve betweem them and the truck incase of leaks. The cab control unit tends to go bad quite often and needs to be checked. Flat out replace every fuse and relay on the unit, i recomend the type that light up when popped. It saves a LOT of time. The alternator should be function tested and honestly if its the old style 60 amp one just replace it with a 110 as the 60s were pretty unreliable.

    The AC compressor, dryer and condenser units tend to have a lot of issues and need to be function and leak tested. Also i recomend you just toss the condenser that comes with it and get the upgraded verson as the stock one especially on the older units cant keep up in hot weather. Get the upgraded blower for inside the cab as well if you have the older one. The stock one is crap and i replaced mine 9 times in as many months but issues stopped once i got the upgraded one.

    And thats pretty much everything i delt with on mine over around 1000 hours. Honestly, good luck as thermocants are either good or they are crap. There is zero inbetween with them ive found. But if you at least check all the above, it should be a decentish unit....should be
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  3. dngrous_dime

    dngrous_dime Road Train Member

    Jan 28, 2014
    Lansing area, MI
    Sounds like he may as well just go buy a new
    wifi_guru, Siinman and Arctic_fox Thank this.
  4. Arctic_fox

    Arctic_fox Experienced mx13 execrator

    Sep 16, 2016
    I wish i had when i got my truck lol. The one that came with it I spent almost as much on repairs as i did for my new green apu.....and then it threw a rod at 2500 hours anyway. And the ones ive used on 4 previous trucks all had near identical issues.

    That said most of that list is check only. The only things he will for sure need to replace are the sensors, the condenser, the cooling fan on the side, the fuses, the wireing, and the dampers for where its mounted to the frame and maybe the alt if its the old 60 amp verson, if he does that will head off the majority of issues. And he is looking at maybe 2k for the whole lot.

    The cut off valves, hoses and wireing are a given as its unlikely what he got will even work on his truck and will need to be rerun anyway so may as well do all of it at the same time as the cost diffrence will be $10s of dollars instead of hundreds if done during the install.
    Vampire, Siinman and pavrom Thank this.
  5. scoobertdoo

    scoobertdoo Road Train Member

    Nov 11, 2020
    thermoking APU are junk.
  6. wifi_guru

    wifi_guru Light Load Member

    Feb 22, 2024
    what i am thinking and if he don't know how to install it how much will the shop soak him to install it how much did he pay for it? and wait till it breaks down there goes more $$$ out the window. for repairs i been hearing in the range $ 600.00 to $ 1,200.00 a pop screw that!!!
  7. mitmaks

    mitmaks Road Train Member

    May 16, 2014
    Keep up on maintenance and you'll be money ahead.
  8. oicu812

    oicu812 Medium Load Member

    Sep 24, 2010
    That was my experience also. I had around 14,000hrs on mine when I sold my truck. I had it on 2 trucks and overall I would do it all over again.
    You have to do some maint. on them but that is a no-brainer. Also, what Arctic_Fox said about an isolation valve is a must.
    Vampire Thanks this.
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