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D6D engine overheating

Discussion in 'Dozers' started by .RC., May 7, 2022.

  1. .RC.

    .RC. Senior Member

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    Qld, Australia
    So I have come to the conclusion my D6D has a cooling problem. It is not a dire cooling problem but it renders the machine unusable for longer periods in summer. The problem is I am pretty sure not in the transmission as it never gets any further then 3/4 of the way through the green, even when the engine reaches the red. The engine will not start running hot until the torque converter gets at least 1/3rd into the green which takes an hour or more. Then if I load the engine up, the temperature it will slowly creep up to the red.

    It has done this ever since I bought it a couple of years ago. If I look at the machine I can see the following has been replaced. Transmission water cooler and the transmission radiator cooler, the fan belts are tight and the pulleys are new. The water pump also lacks paint so I suspect it also is new. I pulled the thermostat and checked it and it is fine. The only thing not checked in the engine timing, which I have heard can cause heating issues.

    Which leads me to think I know what the problem is. The radiator core which has also recently been replaced. I have flushed it and washed it to no avail, however what I noticed is that the core they used has mighty big gaps between the fins so I looked up the core details which led me to an Australian manufacturer of cores and they list this core as having 6.5 fins per inch, while nearly every other radiator core they make for cat machines lists 9 fins per inch and they list a lot of cores.

    So does is sound feasible that they installed a core that the manufacturer puts in the incorrect number of fins for the application, most of the air getting blown through does nothing as it goes no where near the fins.

    The core is a 4N6298
     
  2. AllDodge

    AllDodge Senior Member

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    Wondering if it actually is getting hot. Have you checked the temp with a IR temp gun at the thermostat.
     
    Vetech63 and Delmer like this.
  3. Delmer

    Delmer Senior Member

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    Yes, check the temp of the thermostat housing going to the radiator, and the water pump inlet coming from the radiator. When the temp is as high as you dare run it. Those temps should tell us something, assuming the radiator is clean inside. Have you drained the coolant to check for sediment? is it running antifreeze, and what concentration? you certainly don't need more than 50/50, the more concentrated the antifreeze, the thicker it is and the less heat it absorbs, pure water is a better heat transfer fluid.

    6.5 instead of 9 fins per inch wouldn't make a difference in my world, but I don't work in the temps you work in. I'm used to a larger degree of cooling system reserve...
     
  4. tctractors

    tctractors Senior Member

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    A good test for the temp regulator is to use your heat gun on the oil filter as it will show the drop in temp as the regulator opens, the water travels up from the water pump along the side of the engine into the engine oil cooler, then on to the trans cooler traveling down 1 side of it then passing up the other side and then entering the cylinder block, the pegging up of the oil cooler water tubes is a very common problem so I would start by checking these, the transmission cooler also has a regulator placed down in the chassis that controls the oil flow into the air blown radiator style cooler or the water cooler, so you need to use the heat gun on lots of areas to gain a good picture, water/oil coolers need stripping on CAT D6 tractors around every 3 years as they block up easily, you will need to buy a cooler gasket kit to strip and rebuild them, also check that your fan is fitted correctly, if you have any doubts put up a picture. tctractors
     
    Rusted, Nige, hosspuller and 2 others like this.
  5. .RC.

    .RC. Senior Member

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    Thanks everyone. I had not considered water flow rate. So I gave it a run yesterday although the day was overcast and only about 20C and I was only piddling around with it so the machine got no where near hot.

    Here are some temp gun temperatures. Before the engine oil cooler it was 84C. On the engine oil cooler it was 98C and on the transmission oil cooler it was 82C. On the oil filter it was 91C.

    Here are some photos where you get to see my hands.

    20220508_135659.jpg 20220508_135708.jpg 20220508_135716.jpg 20220508_135750.jpg
     
  6. .RC.

    .RC. Senior Member

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    Location:
    Qld, Australia
    I found this thread. Same radiator core, similar problem. Pity the thread did not have an outcome. Gives me some temperature drop figures to test for as well.

    https://www.heavyequipmentforums.com/threads/operating-temp-d6c.77931/

    Although one gets the appearance that heating issues in the D6C/D machines were more common then in other Cat machines. Or there are more of those machines still about since the internetz became common.
     
    Last edited: May 11, 2022
  7. Delmer

    Delmer Senior Member

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    The temps when it is as hot as you run it will tell something, the radiator temps and the oil cooler like TCT said.

    The numbers in post #5 might mean something to TCT, but they'll be more obvious if you get the coolant up to or over 100C.
     
  8. tractormech

    tractormech Senior Member

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    Have you checked the water pump? I changed one on a 3306 in a truck that was running hot and it fixed it. The impeller may be worn or slipping on the shaft.
     
  9. oarwhat

    oarwhat Senior Member

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    buffalo,n.y.
    Check the oil cooler inlet. Very common problem as TC has said.
     
  10. .RC.

    .RC. Senior Member

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    Not checked the water pump yet. It has no paint on it so I suspect is newish. The machine is sitting doing very little, and I have not had time to pull it apart just yet.