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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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    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.
     
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  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
     
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  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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    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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    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.
     
  11. .RC.

    .RC. Senior Member

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    I pulled the oil cooler out. It looks clean, but when I ran a 4mm welding rod through it a lot of rusty gunk came out of probably 50% of the tubes. The castings the water runs through were surprisingly scale and rust free for such an old engine.

    I pulled the cover off the water pump and it looked good inside. Impeller was tight. While the blade was off gave the radiator a good blow and then wash out.

    So I pulled all the engine side screens off and have put it to work. It is now running cooler then ever before, although it is also not a hot day.
     
    nicky 68a likes this.
  12. R.D.G013

    R.D.G013 Well-Known Member

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    Not sure what type of fan U have on it but if its on backwards that can cause overheating, it might look right and still blow air but won't be enough if its on the wrong way round. Seen that happen before.
     
    shopguy likes this.
  13. Queenslander

    Queenslander Senior Member

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    Are you using ELC RC?
    Iam a big fan, a quality coolant but no dearer than some of the offerings from the likes of Super Cheap Auto.
     
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  14. .RC.

    .RC. Senior Member

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    The fan is all right and proper.

    I am running an ELC coolant, but it is Toyota Red ELC. I get the concentrate from a mechanic friend for his price and mix it 50:50. The Toyota red is for older engines. I did try some cat coolant in my 922 loader once. It just leaked all out of the head and I had to get a new head. The pre combustion chambers would not seal with the new coolant and turns out the head was cracked anyway. I was told that only use the Cat ELC in either new rebuilt engines or just newish engines.
     
  15. Nige

    Nige Senior Member

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    FYI that's a "conventional" inorganic coolant, not an OAT-based ELC. The Toyota OAT-based ELC is the pink variety. The red coolant may well have "extended life" on the label but that doesn't make it an ELC. I'm not trying to say the coolant is your problem BTW.

    In my experience ELC coolants will find weaknesses in cooling systems far faster than conventional coolants. That does not IMO make them unsuitable for use in older machines.
    IMO whoever told you that was expressing an opinion that I personally don't agree with.
     
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  16. tctractors

    tctractors Senior Member

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    Well I liked your bit of script on the Cooler but the D6D has 2, the water flows from the water pump through the engine oil cooler then on to the transmission cooler, the water flows down 1 half of this cooler turning at the bottom to travel up through the other half of the cooler case, the water then travels into the cylinder block and up to the cylinder head were the temp gauge is fitted (Non electrical) ether gas filled. tctractors
     
  17. .RC.

    .RC. Senior Member

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    Sorry I forgot to mention the transmission oil cooler. It was very new and the internals were in pristine condition.
    I will just have to wait and see what summer brings, it is bloody cold here now. The nights get down to 9C.

    Interesting about the Toyota coolant but it works well for us. I can see how with people with newish machines working full time the Cat ELC would work well.

    Now I have to move onto my fuel pressure problem ;)