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D7H Transmission Heating up

Discussion in 'Dozers' started by zhkent, Apr 29, 2013.

  1. zhkent

    zhkent Senior Member

    Joined:
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    Occupation:
    Earthmoving
    Location:
    Kansas
    D7H, 79Z 1753.
    Problem has been ongoing since I bought the tractor about 2 years ago.
    The problem has stayed very steady and persistent.
    On a cool day the trans will heat up to 210 with the motor running 170. It heats up slowly taking an hour or so if pushing hard, in less than 2 hours it heats up if working easy.
    It slowly gets to 220-230 on 80-90 degree days bringing the motor up to 180's. In 90-100 degree days it's a problem with it getting 230's.
    The trans won't cool done with the tractor sitting still, med throttle or low throttle. It might cool off 10 degrees or so but never cools to the motor temp.
    Things I've done:
    The injector pump was remaned by cat when I first got the dozer.
    Last year I took off the trans cooler and cleaned it, some blockage. Pump preasure was like 20 psi low-put a cat reman on.
    Checked temps gauge with a temp gun.
    This winter I had the torque rebuilt, all new hoses on the tranny and torque, new radiator, cleaned the tranny cooler-no blockage.
    No change.
    Did more preasure checks. Everything checked out ok except the pump drive lubrication. This port is on the front of flywheel housing, same side as trans cooler. it checked 30psi low idle (40psi +- 10) 45 psi high idle (70 +- 10 is the spec).
    Anyone have ideas?

    Also changed filter and oil, checked screens which are clean. Old oil smelled burnt.
    Trans holds, shifts just like it should. Brakes and steering clutches are excellent.
    Tractor will coast on a slope.
     
    Last edited: Apr 29, 2013
  2. watglen

    watglen Senior Member

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    Farmer, drainage and excavating contractor, Farm d
    Location:
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    I followed this problem in previous threads, looking forward to hearing suggestions

    Ken
     
  3. zhkent

    zhkent Senior Member

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    Kansas
    Found the Previous thread
    Preasure checks with hot oil
    Priority valve 415 (420 +- 20)
    Transmission lubrication 31 (31 +- 5)
    Converter inlet preasure low idle 50 (80 +-15) high idle 90 (100 +-10)
    Converter outlet preasure 50 (60 +- 10)
    And the Pump drive lubrication low idle 30 (40 +- 10) high idle 45 (70 +-10)
     
  4. TXGOAT

    TXGOAT Well-Known Member

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    valve body?
     
  5. oldirt

    oldirt Senior Member

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    iowa
    have you replaced the trans and torque scavenge pumps? I would much rather have put on a new cooler core. If these are all good and it still builds heat that leaves the transmission.
     
  6. zhkent

    zhkent Senior Member

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    Occupation:
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    Location:
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    The scavanger pump is part of the transmission pump that has 3 sections.
    I replaced the radiator because 2 sections were leaking, put in all 8 new and kept the old ones for spares. Also new tracks, a final drive rebuilt that only had mud holding the oil in, all new trans and hydraulic hoses, cat rebuilt all the cylinders, and I attempted paint.:)
    Used a heat sensor today to check the temps like suggested in the first thread. I couldn't find much variance in the water temp at the trans cooler 170 167.
    The trans lines going in and out of trans cooler were 190 168
    The gauge was reading 210.
    I'm pretty sure the gauge is right. On hot days the trans heats up, then the hydraulic slowly climps to within 5 or 10 degrees. the trans gets to 240 or so, the hyd slowly comes up to 230 and the hyd alarm goes off.
    Is this a possibility that the pump drive lubrication is dumping way to much oil into the converter housing?
    I haven't dived into the clutch and brake valve body or the transmission valve body.
     
    Last edited: Apr 30, 2013
  7. CAT793

    CAT793 Well-Known Member

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    I chased something similar when I was a boy and after a day testing I popped the little cover off the back that has the P1 and P2 Pressure Nipples and they both had damaged O-rings on the jumper tubes to the Valve Pack.....
     
  8. stinkycat

    stinkycat Well-Known Member

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    retired, disabled vet
    Location:
    Ohio
    I don't what kind of temp sensors you but you should be able to pull and test with a known heat source and verifier the gauge reading if they are thermsister type and can find the milivolt range use a multimeter in line and check milivolt output
    Heat guns are great but can be way off. I'm sure that you know that using the heat gun the area must be clean and has a dull non-reflecting surface
     
    Last edited: May 1, 2013
  9. JeremiahSr

    JeremiahSr Well-Known Member

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    Location:
    Houston, Tx
    Them transmission pumps are bad about causing this problem. With all the work you have already done it would not hurt to pull it and tear down for inspection.
    What happens is this Direct Displacement pump is good enough to supply good pressure for brakes..then transmission...then the it starts to get a little weaker onve it finally gets to Lube. The pressures are set with relief valves....even though the pump can show to have good pressure...this does not mean it has the VOLUME to supply everything the proper amount of oil that each system requires. So when the pump is showing good pressures in several places everyone overlooks it but in reality an internally scratched pump could still supply good pressure to the places it has priority but not move enough oil to supply everything with a sufficient amount of oil...ecspecially in convertor and what is left to go to the cooler.
    My next suggestion is to stay away from aftermarket pumps. They are over 1K cheaper and sound like a good deal. I have never found 2 from any place that EVER held up any amount of time. Some people buy the new aftermarket pump, tear them down and swap the bushings to neew Federal Mogal bushings and claim they are a little better but i found buying the good high dollar pump from Cat to be the best bet.
     
  10. Bob/Ont

    Bob/Ont Senior Member

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    Check the priority pressure at high and low idle with hot oil as you shift through all gears and pull and release the steering levers. Then put the park brake on. Record all presures and post them here.
    Later Bob
     
  11. CAT385

    CAT385 Member

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    dubai
    pls check the brakes are 100per released before moving dozer,binding brakes can generate heat and rise tc temp too.in very lowidle with second gear dozer has to overcome its inertia
     
  12. zhkent

    zhkent Senior Member

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    Location:
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    87 degrees here on tuesday, under 40 and rain today.
    But went out and warmed dozer up, 3rd gear 1/3 throttle 20 minutes or so got the torque up to 160-180 range, then took more pressure tests.
    Pump pressure at the filter housing 400 psi low idle (390 spec) 470 high idle (475 +-25)
    Left clutch 300 (335 +-25) clutch pulled 0 (less than 10 psi)
    Right clutch 300 (335 +-25) clutch pulled 0 (less than 10 psi)
    Left brake 390 (410 +- 20) brake on 30 (less than 10)
    Right brake 390 (410 +- 20) brake on 25 ( less than 10) The brake pressures off are my doing. I adjusted the steering and break control valve - the dozer would yank your socks off turning. When the clutch was pulled there was no clutch release then braking, when the clutch released the brake would be on already. Made it hard to make smooth turns. The clutches will release now without the brakes dragging. Haven't had the brakes be weak at all when turning.
    Bob/Ont checked priority valve like you suggested. Burried the blade in but tracks would spin at high idle, the rain and sleet didn't help. so ended up at about 1/3 throttle going through the gears, no clutching, right then left clutch in each gear, right then left clutch and brake each gear. The readings were pretty consistant at 405 410. In gear 410, clutch activated 405, clutch and brake activated 410.
    neutral with Park Brake on 415
    In neutral low idle 395 (no spec) high idle 455 (420 +- 20)
    I got a reading in 3rd gear at high idle 435, clutch activated 425, and about then it started spinning the left track, so backed off throttle.
     
    Last edited: May 2, 2013
  13. zhkent

    zhkent Senior Member

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    Cat 385
    I'll try the 2nd gear low idle when I get to run after the rain. I do have the dozer where if I'm backing down a slope and pull a clutch that side will free-wheel ahead of the other side.
     
  14. Bob/Ont

    Bob/Ont Senior Member

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    Looks like you don't have an oil flow leakage problem. Are you pushing hard in second instead of first gear? Those H tractors have things cut to the bone as far as oil flow goes. Not like the old days with a 40 gpm pump circulating oil.
    Later Bob
     
  15. zhkent

    zhkent Senior Member

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    Bob/Ont - 1st gear pushing, back up 2nd half throttle. I run steady and push a load and on a 100 degree day I could understand if it wants to heat up some. Seem's it ought to cool down if I just let it run with no load at 1/4 throttle. It doesn't. Thanks for your help, this rules out oil flow problems in the steering and brake valves, and the transmission?
    JeremiahSr - replaced the transmission pump fall of 2011 with a cat reman and it made no difference.
     
    Last edited: May 2, 2013
  16. core

    core Member

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    Have you checked your fan speed at hi and lo idle, im guessing it will be a hydraulic fan , could be getting sluggish
     
  17. Construct'O

    Construct'O Senior Member

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    Location:
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    As far as fan goes how are the pulleys how bad are they wore? Have you had to change out the belts lately because they are coming apart at the top side from setting to deep down in the pulleys.If so pulleys need replaced or regroved.

    Friend of mine had a D6R this summer running hot,they changed out the sizing on one of the pulley and it speed up the fan ,and he said it really cooled the machine down.I don't know what pulley they changed,but sounded like it is working.

    I have a older D6R that runs hotter then i like,but have it cools down as soon as you stop for just a little while.Will be working on it here this summer.Will be looking at changing out pulley size if things are still working good for my friends R.

    Are you running engine in closers? In grass and clearing trees stuff will suck in from the back of the machine and get into the radaitor.Might try inclosing the back,underfuel tank.If your running ripper might have to make something,but cat has a guard for below the fuel tank.Two machine of mine has them and help to keep a lot of the trash out ,which comes off the rear track area.

    Keep us posted.Good luck
     
  18. Mjrdude1

    Mjrdude1 Well-Known Member

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    I thought on the H's the trans cooler is mounted to the engine and cooled by engine coolant. If the engine is not heating up the cooler could be at fault. Also if I remember correctly there is a thermo valve on the trans oil to bypass the cooler when cold.
    I may be way off base here as it has been a few years since I worked on an H model.
     
  19. zhkent

    zhkent Senior Member

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    Mjrdude1 - The transmission cooler is on the left side of engine and cooled by engine coolant. This clutch steer machine does not have a hydraulic cooler mounted by the fan, the differential steer ones do.
    Construct'O - The pulleys are good, belts newish and tight. I do have inclosures. The transmission heats up regardless. Fall of 2011 I was packing silage and the stupid transmission wanted to heat up. I'd clean out ther radiator well, the motor would be running around 180 and the trans would heat on up. And for some reason, I assume it's because the hydraulic pump is picking up the heat from the flywheel housing, the hydraulic temp would slowly follow.
    Pushing some dirt on the next job and the motor is fine, hydraulic fine, transmission slowly gets hotter as the day goes on. It was hot, but I was babying it. Eventually the trans climbs to 240, the motor is running 200 ish, and the hydraulics hit 230 and the alarm goes off. This was daily and has stayed consistent. The transmission cooler is clean. The transmission pump replaced with a reman cat, new hoses, new filter, magnets are clean, and rebuilt the torque convertor. I haven't had the alarm going off yet, but it's behaving just exactly the same. I avoided building new ponds with it in the heat last summer, but that's not going to be an option this summer. Basically I limped it through last summer.
    I think it is a flow problem with the pump lubrication and oil cooler. (I thought it was the torque convertor and was wrong there though - :Banghead ) The fact the pump lubrication is low makes me wonder if somehow oil is dumping into the flywheel housing flooding the convertor making it hot, and letting the oil that should be going through the cooler bypass the cooler.
    Would taking a catch pan and see how much oil is coming out of the convertor be something to try? Or is it way more than what I could catch?
    Would taking a flow meter test on the oil cooler or line coming to the convertor be the thing? I'm not equipped for that though. Quite a ways out from a service truck so that would be kind of pricey.
     
  20. Construct'O

    Construct'O Senior Member

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    Sounds like you have done alot of the right things ,but isn't working.Engine and convertor temp run hand in hand.Engine heats then trans temp comes up.Trans heats engine temp comes up.The way your describing things the trans temp is the first to come up,so i'm guessing the engine isn't the start of things in your case.

    Had a go around with my D6H,different problem,got it fix post on here 9 pages ,but finally got it solved.

    My 6H the convertor has always run right up there ever since it was new. 210 degrees by the gage.It got to running hotter after it was rebuild.2500 hours later the main bearing and seal went out and filled the housing up with so much oil that it was running out around the starter.New one here on me.

    Pulled the convertor and the front seal blew because of bad bearing.Talk to Cat and told them old bearing made it to 15,000 + hours and rebuild couldn't make it 2500 hours.So they redid it and too there credit helped out on the cost.After this rebuild it has run cooler then ever.

    Couldn't hurt to try draining the convertor and see how much oil you get.Shouldn't be over a couple gallon from other post on here.On the R there is a return screen at the transmission pump, have you checked it out,not sure on the H.It is the line coing from the trans pump to the convertor there is a small scren there also fits in the hose or convertor,by the parts book 3t6471.My helpers just did this last week because one of the C clamps on the hose was broke and seeping oil where the screen sets.

    Think there is a tube coming down from the trans pump where there a screen also.They didn't lose much oil.Screen should be clean.Have you checked the one in the rear of the transmission.Your lose oil there ,but you can get it out and back in if you have help and hurrrrrry!!!!!!

    My machines are all diff steer.What about hydraulic filters.have a spin on one behind the trans filter on diff steer.Have you check trans filter by cutting it apart.Last time trans oil changed.Probably did that when you did covertor,but wouldn't have had too,unless needed.

    If it was the engine first the is a oil cooler on the left side that has coolent running through it that over the years get plugged the doesn't cool the engine oil and the heat in the engine temp will be the first to come up the the trans start creeping up,but sounds like your having the opposite problem.

    Keep checking things out, and posting here.Has the engine had the fuel turn up much?

    Long post just thought of something else.You mention adjust the steering clutch and brak likage.Are you sure you have thing adjusted correctly.If the brakes are set right and dragging just so much the slights that would build up heat.Might not hurt to start check thing the if your sure all the other thing are in place.Brakes ,steering clutch working right, check there!!!!!!!!