1. Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

Komatsu d61-12 Transmission Overheating

Discussion in 'Dozers' started by barnmb, May 14, 2019.

  1. barnmb

    barnmb New Member

    Joined:
    Feb 18, 2019
    Messages:
    4
    Location:
    Manitoba
    Hi I have a Komatsu d61-12. We are using it mostly for clearing land. After pushing for 2-3 hours the transmission overheats. if you let it idle for 10 minutes or so you are good for about another hour again. We recently rebuilt the oil cooler radiator and noticed no improvement. Any ideas where to look or what to check next?
     
  2. John C.

    John C. Senior Member

    Joined:
    Jun 12, 2007
    Messages:
    6,519
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    Check stall speeds, pull strainers and filters checking for foreign material, use an infrared thermometer to identify where the heat is coming from and the difference in temperature between the inlet and outlet of the cooler.
     
  3. bam1968

    bam1968 Senior Member

    Joined:
    Nov 2, 2014
    Messages:
    334
    Occupation:
    Excavating Contractor
    Location:
    IA
    I had a d65-12 that had similar symptoms. The problem was that the brake peddle was stiff and not releasing all the way. Just my $.02
     
  4. barnmb

    barnmb New Member

    Joined:
    Feb 18, 2019
    Messages:
    4
    Location:
    Manitoba
    Finally getting around to working on this again. Got a guy to check it over a bit and he said the engine was running a little to slow for the torque convertor to lock up properly. He bunmped the rpm up 100 which was within the spec given in the manual and said it tested fine after that. A few days later I went and ran it hard and same thing after 2-3hours. When it does this if you idle down just a bit it will stay below overheating more or less indefinitely. When it was overheating I put an infrared thermometer on the transmission cooling lines beside the engine. In seems to be fairly consistently 125-130ºf in and 108-112ºF out. Sometimes when you idle down after taking the temp it seems like it goes up to 150º in but not always. It is definitely not caused by the brakes dragging. It rolls down a very slight incline.
     
  5. barnmb

    barnmb New Member

    Joined:
    Feb 18, 2019
    Messages:
    4
    Location:
    Manitoba
    He also said the stall speed was in spec in 3rd not sure if he checked in the other gears or not. I pulled the strainers and there was a bit of metal muck but no chips or chunks.
    Also pulled the the main relief valve. In here were 2 chips, one of the valves was a bit messed up but polished it up with 600grit paper and it all seemed to work fine after that. Or is there no way that something like that would work after being a bit messed up? What are the tolerances?
     
  6. John C.

    John C. Senior Member

    Joined:
    Jun 12, 2007
    Messages:
    6,519
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    You check the stalls in third gear. If it is good there, then all is good. I didn't know they had a lock up converter in a D65. As I recall on the machines I've worked on that did have that type of converter, they locked up on load and not engine RPM. The temps you are getting on the piping is not out of line with what I have seen on other machines so I'm not real sure if your problem is real or a phantom. I'd suggest taking an oil sample next to get a read on what is in the oil. Does this machine have an air to oil cooler or an engine coolant to oil cooler? Making sure the fins are clean, the belts are in good condition and adjusted properly and that there is no damage to the blades on the fan are some other things to check.
     
  7. barnmb

    barnmb New Member

    Joined:
    Feb 18, 2019
    Messages:
    4
    Location:
    Manitoba
    D61 but yes he said they did. I think its called an engine coolant to oil cooler. The bottom third of the main rad is for tranny oil the top 2/3 coolant. Coolant was 120 in and 85 out when I checked last but did not check today. Fan belts were new last week, pulleys a little worn but belts sat well. There is minimal damage to some of the blades on the fan but could hardly imagine it would be enough to cause it but who knows. Thanks for all the help.
     
  8. John C.

    John C. Senior Member

    Joined:
    Jun 12, 2007
    Messages:
    6,519
    Occupation:
    Machinery & Equipment Appraiser
    Location:
    Northwest
    My mistake on the machine model. I've not worked on a d61.