have a 1989 d6h and the darn thing works perfect for an hour or more but after that the trans temperature get real hot. it pushes great till oil heats then things start to happen . when your switching from forward to reverse sometimes you put leaver in gear and it will do nothing? we have changed transmission filter and cleaned screens and the screen was full of rust but cleaned put together but no difference.
Did u check the oil cooler ? I have seen a trans cooler get plugged up with gunk on the water side and not cool.
with a heat gun the cooler does seem to work but that being said I have not taken it apart . I did clean suction screen for transmission pump and it was dirty. there suppose to be a screen on TC but I have not found we're it is
It's worth checking. I've seen one plugged up with sludge and silicone from repairs ro the water system. Caused the trans to heat up.
so getting at tearing apart cat and this is the valve that lets oil to trans oil cooler does it matter that it looks like this?
How hot is it getting does brake pedal come all the way back up?
ya brake comes all way up. the transmission oil will go to 210 easy after hour of working it . engine temp stays at 170
Yeah that's hot need to take some pressures to check oil flows check temp on trans cool from back to front and water temp going in and out will give you a good idea of cooler efficiency. Would to a stall test put blade into a pile with brake on rev machine in high gear and watch torque out let pressure.
well that was fun taking off god what a job ! Don't think it was ever taken off before plugged solid I think . coolant side is clean . oil side is plugged solid is say I blew it out a bit before picture . can a guy press that cooler out?
Lots of rust in system drain bevel gear case and flush try off road equipment or costex tractor parts for a cooler
It would cost more to attempt to clean it than a replacement is worth. Use the old one for a boat anchor and find a replacement from somewhere.
going to put new one in 770 bucks not to bad it's suck a bear to get out and in it better be new
so I did try to blow air through oil part and it would go through at all so i am hopping that is a major part of what was causing the heating problem
wouldn't go through.
picture didn't go through before sorry
Looks ugly in there, hope that's the root of your problems. What's the service history on the trans oil and filters? The cooler valve looked pretty scorn up in the early pics.
we bought at a rb sale so guess we didn't luck out this time but hopefully can get it running properly learning lots about dozer that forsure
is there any kind of cleaner to put in oil to clean whole system? Was even thinking about putting diesel in oil and run for a bit no load of course and change it couple times.
Not sure about diesel, haven't tried it personally. When we did our d7 we did a few cans of hydra tune from seafoam with new filters and ran it for a few hours to warm it up then drained it. It was milky from a bad trans cooler. After that we drained and put new cat trans oil and filters. The oils been crystal clear after that.
I have run straight diesel in a crankcase for a couple of minutes on 2 or 3 pieces of equipment to flush them before without any trouble. Drain and refill with oil. I usually only ran them a couple of hours and then changed the oil yet again and good to go then. Let's just say that two of them went for a swim as the reason for flushing.
so much room lol
We would mix a few gallons diesel to engine oil to flush but never straight, bad enough to be diluted but need some lubrication especially on a startup. And also changed oil quickly first time and early a second.
so I guess I have to take torque converter out . I changed the oil cooler and it works except it heats motor up know so the TC is coming out . how hard a job is it to take out and can a guy rebuild it himself?
You may want to check the screens on the torque as noted in other posts, they get choked causing the converter to flood and they get hot QUICK. Seeing the cooler loaded so heavily I would seriously look to the screens.
think someone took screens out cause I can't find any on bottom of TC . i removed all most all hoses to find them and no luck. one thing I did notice when I took machine out again when your pushing the engine does not come down at all with full load .
Do 6hs have scavenger pumps on the tq?
there just one pump as far as I know but I may be wrong
I did not see the full S/N but unless this is different than most Cat transmissions there may be "one pump" BUT that pump most likely has more than one section to it and one of those would be the scavenging pump section. Just an example: This is the pump out of a D6H II 8SK*****
Yes that's what's in there and it does have a scavenger side to it maybe I should check that to first
Ser # 6fc00687
what does the scavenge side do?
I did get about 5 and a 1/2 liters or more than a gallon of oil came out of TC to not sure what it's suppose to be
Scavenger side is what "sucks" the oil out of the converter housing and pushes it back to the transmission sump.
when taking axles out do you have to remove something else inside to get transmission out?
hi ,you don't need to remove axles from machine or transmission to remove torque convertor the torque convertor mounts on the back of the engine and is lowered to the ground using a mounting hole already in the top of the cabin with a chain block or lever block stick some cribbing under the tracks to raise the machine to make it easier to work on mark
sounds good thanks . I have machine in shed finnaly and I think I want to take transmission out to just to make sure it looks good in there I took axles out and pulled the inside axles out a bit but it seems like it get tight when trying to remove trans with screwing in the bolt . did I pull inside axles out to much maybe?
well got transmission out not even a bad job but a forklift does help. trans looks good some sludge on floor of housing going to clean up . all steel hoses are looking good inside but will try to check with air pressure to make sure.
Had a d4h where the bolts inside the torque converter broke off one by one and would create heat. We checked pressures, changed radiator cores and all. Finally the rest of the bolts broke and machine quit moving.
the TC is coming out this week. looks like not to bad to take out buy will find out
I will also tell you it was cheaper to have cat rebuild my original then putting in a reman cat unit.
Had a couple Allison TC's that were overheating and the cause was the flange the bolts that held the two halves of the converter go through had a crack around the outside of the housing. This would cause oil to leak to under load, very much like your D4H with broken bolts, this excess oil in the converter excess oil in the housing would overwhelm the scavenger pump and create drag and heat.
well got TC out and apart. the thrust bearing is wore out and caused the stator to rub on turbine got a few pictures I'll try to post
needs turbine halfs and a stator and bearings of course and seals not sure if I should do myself or take to cat anyone put one together ?
That would do it. I would check with Cat as to reman on your existing unit, those stator/turbine sections may still be functional if not all that pretty.
well was going to rebuild TC but since I am in Canada and get screwed over buy parts depots cause dollar is **** I have bought a new one complete hope it shows up soon
update got new TC in and that part works again but know after 2 hrs of running transmisson is still getting hot guess will be checking the pump next . the oil now cools down if you sit for a bit but it will hit 200 after a bit
Did you replace the transmission oil cooler?
ya put a new one in. the oil side was plugged solid with dirt . think machine had little maintenance before we got it
so finnaly figures out why we had a heating issue on the dozer , in the above picture on the filter housing there is a filter sensor on ours. for some reason someone had cut the wires on sensor and bypassed it so light would not come on in cab. so I hooked back up and long story short someone had put the spring and valve or slug in wrong! thats why sensor would stay on and transmission would heat. the valve or slug was in wrong way causing major restriction. not only that the manual shows it wrong on our machine anyway .
Good hunting 4730
4730.. I sure hope this is all that you need to fix. I used to think the procedure was that when you do the convertor you do the trans at same time because somebody before you overheated the whole shebang enough to ruin seals all down the line.. best of luck.
Nice to hear you finally got to the bottom of it. Not so nice the $ you had to spend to get there. It's always a major PITA to have to dig into a machine that someone else has "interfered with" previously. Just goes to show that you have to start with basics and don't assume anything. Especially don't assume that because it was "that way" when you pulled it apart that "that way" is correct, as you found with your trans filter bypass spool assembly. Bloody frustrating ........ the error in the manual doesn't help either, because if the manual shows it that way then that's the correct way, right..? What you refer to as a "sensor" is only an on/off switch BTW.