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Please Help Cat D8L Transmission Overheating

Discussion in 'Dozers' started by stabber, Aug 25, 2019.

  1. Mark250

    Mark250 Senior Member

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  2. stabber

    stabber Active Member

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    That looks 100% like what I have, any good way to check the relief valve?
     
  3. Mark250

    Mark250 Senior Member

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    use the test port in the picture

    upload_2019-9-10_8-48-6.png
     
  4. StanRUS

    StanRUS Senior Member

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    60-65psi < low, low
    Spec 80psi +/- 5psi, brake applied, 3rd gear forward, torque converter stall

    Engine High Idle, Spec 2020-2120
     
  5. turbo8781

    turbo8781 Well-Known Member

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    I don't, The 8L we have now is the only one i've been around and I don't know the part # but I'll bet somebody else does.
    It is easy to take apart and inspect the piston tho. You shouldn't loose but about a cup or maybe a quart of oil.
    No, you can't run it without, It must have a way to relieve the pressure and circulate the oil.

    You may have some other components getting tired/ weak but for your heating problem my money is on a plugged up cooler. Ours was tripping the warning light regularly and after I cleaned the cooler I can't get it over 190' F no matter how hard I try
     
  6. Nige

    Nige Senior Member

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    This issue came up earlier Stan, but there was doubt regarding the accuracy of the 250-3000psi range test kit gauges that the OP was using. In post #49 above he alludes to having repeated the tests using more suitable gauges but forgot the piece of paper with the results. I suspect that you're right and TC out pressure will come out low, but I wouldn't like to say that for certain until he posts the results.

    Even if TC Out pressure is low that still doesn't explain to me why it takes almost 5 minutes for the TC Out temp to fall @ HI in neutral after the high temp light comes on. That indicates problems in the cooling circuit somewhere.
     
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  7. Dave Neubert

    Dave Neubert Senior Member

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    Pull the piston out of the valve and make sure it is free if it is bypassing it would be stuck open not shut
     
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  8. nicky 68a

    nicky 68a Senior Member

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    I see the cooler is still on the tractor.
    It has to come off and be cleaned or replaced I think.
    Removing it will be easy compared to the hateful water pump job.
    I feeling you are pissing uphill into the wind until you get the cooler off
     
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  9. stabber

    stabber Active Member

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    This weekend I will remove the cooler, I suppose there isn't any way around draining all the oil?
     
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  10. Nige

    Nige Senior Member

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    Nope, sorry.

    Just another thought from left field.....
    Reinforcing what Nicky said above, get the cooler off and clean or replace it. After that wouldn't it be something if the TC Out pressure changed because of the differing resistance to oil flow through a (now) clean cooler..?
     
  11. stabber

    stabber Active Member

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    Nige,
    That was my thought exactly … I just need to motivate myself to get under the machine in 90+ deg weather … I guess at least i'll be out of the sun :)
     
  12. StanRUS

    StanRUS Senior Member

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    OK 90+ with humidity, not fun.

    You won't have much oil to drain just working on the cooler. After you get the cooler off. Drain the oil and tape up the openings. Use 1/8" diameter brass rod, rod out the tubes and pressure washer or use solvent gun.

    I am located in S.Cal and our D8Ls, D9s are all re-powered with electronic emissions engines (if they're not used for AG). Normal emissions engine temp 190-210F and normal TC-Trans temps 220-230F. Working ambient temps 120F+ are normal.

    Flicking Trans light @ 240F, just tells the operator to ease off a bit, like use 2nd instead of 3rd forward-reverse. Accumulated dirt stacked up in the crankcase guards will also cause higher operating temps because of the insulating dirt.

    Reference:
    Torque Converter Outlet Relief Valve: 3T3505 VALVE GP-RELIEF part of 7G5126 Lines-Power Train Oil page 137
     
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  13. stabber

    stabber Active Member

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    Update - I removed the oil cooler and took it to a shop in Oklahoma City that cleans and services the coolers regularly. They said mine wasn't that dirty :-(, so I will put it all back together this weekend. Just a quick thought I had, on the left side of the cooler, there is the small outlet hose that feeds back to the engine (Left side sitting in the seat). Is there any relief valve on the water side that could be faulty or restriction (thermostat) that regulates how much coolant flow comes into / across the cooler? This was a cold(er) weather machine coming from Wisconsin ….
     
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  14. Nige

    Nige Senior Member

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    Once you get everything back together snap a photo of the hose you’re talking about and post it up.
     
  15. nicky 68a

    nicky 68a Senior Member

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    It's a shame you didn't find the cooler dirty Stabber as it would of been an explanation.
    At least you've eliminated it though,and it may have had just a bit of trash in it that's now out.
    Were any of the tubes blanked off at all?
     
  16. StanRUS

    StanRUS Senior Member

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    Tube blockage or partial restriction, e.g. slowed fluid flow , 10%, 25%? Unknown!

    Hose Assembly: 6N8785 approx 48" length, oil cooler torque converter bonnet (left side sitting in seat) to engine. No valves or pressure regulators. Remove the line and fittings (elbows) and check if there is any type of internal restrictions.

    Radiator: Conventional or Folded Core?
    Auxiliary Hydraulic Oil Cooler? Has or has not?

    Torque Converter flooding? Lock brakes, stall at high idle 3rd gear forward. Use per-positioned 3 gallon capacity bucket. Shut off engine, and quickly remove the screen-cover and drain oil into the bucket. Over 3 gallons! Remove and check scavenger pump for damage-wear, if pump is okay. Remove and repair torque converter assembly!
     
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  17. stabber

    stabber Active Member

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    Weekend update:
    I put back on the new (cleaned) oil cooler, no blanked lines as well as putting in the new water pump and all new seals etc. Man what a job to do with your 6 year old boy! I filled up the radiator with some flush cleaner, and while I was filling it noticed that my seal on the water end of the cooler was spraying out water. I crawled back under it and retorqued the bolts, but water continued to stream out. I figured I would finish filling it with the flush solution, but as I filled it the leak died down then stopped!!??!! I started the beast and ran it about 30 minutes and didn't have any leaks at all???!!?? Now I'm paranoid, should I remove the cooler again and check the gasket? I cleaned all surfaces very well and put gasket sealer on both sides before reassembly …. but I don't want this problem to surface again after I put back on the belly pan …. I ran out of daylight before I could load test it and see if it still heats up …… More to come next week :)
     
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  18. d9gdon

    d9gdon Senior Member

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    Normally those gaskets go on without sealer.

    Did your sealer have proper cure time?
     
  19. stabber

    stabber Active Member

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    I put on cooler Saturday about noon and filled it Sunday about 6pm, and the sealer stated it could be used immediately 500 deg F jargon … oh man now second guessing putting sealant on gasket :-(
     
  20. kshansen

    kshansen Senior Member

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    Not saying it's the case for you but I have seen gasket sealant act as a lubricant and let a gasket slip out of place while tightening the bolts.

    Unless I felt there was a good reason to need sealer most gaskets were put on dry. And when I did use a sealer put it on very thin.

    I would not feel too good about a gasketed joint that was leaking with just the weight of cold water against it. Especially one that was described as "spraying out". Sorry!
     
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