G'day all, I have been helping a mate out trying to diagnose a long term Trans overheat issue on his D4H LGP series 3 and would appreciate any thoughts or ideas please, its been doing it for some time and gradually getting worse. As in it takes less time to get up around 115 to 120 deg c, (approx. 2 hrs) just shy of the EMS buzzer at 130. To date these are the things checked / tested: Dozer is fitted with large wide stick rake and does general clean up work on farms, it operates just fine and has no dragging undercarriage/idlers etc. Full Trans and Steering clutch / brake pressure test, all in spec (done multiple times over 12 months). Added and removed shims in TC outlet relief anyway to see if it made any difference to heating, no change. Dismantled radiator assy and cleaned out tanks/cores, has run Cat ELC since new. Radiator drop approx. 9 deg c and oil cooler drop in to out approx. 14 deg c. Cooling system appears to be working ok and Trans does come down with Eng temp when no load / hi idle. When back to work it heats up quick again, Engine does not overheat at all. Check for pinched or damaged lines to cooler, all good. Also manually checked oil flow into cooler, not done with flow meter but plenty of flow evident. Replaced gauge and sender (no difference). Changed oil to Cat 30W powertrain (was 50W), improvement in shifts (a bit quicker) and seemed to take a bit longer to heat up. Checked resonator valve in Trans (some had issues here) all good, replaced spring and end plug anyway. Done oil drop test on T/C to see if flooding was issue, approx. 2 lt drained out. Decided to remove T/C and strip it regardless, condition almost like new. No parts required other than seals. Pump also checked as is like new also. Where to next ! I did hear that some people added a oil to air cooler into the circuit, has anybody heard of this ? Thanks
Question: When it does get up to the point where the transmission temp warning buzzer sounds, how long does it take for the temp to go back down to "normal" if you run the engine at high idle with the transmission in neutral..? What's the TC outlet pressure with systems at operating temp and trans stalled in 3rd speed..? Radiator and trans cooler temperature deltas are fine. No problem there. TO-4 SAE30 oil will give sharper shift response in your climate conditions. I was always a believer in 50 but have changed my mind over the years. What brand oil are you using..? Has anyone pulled the trans screens lately and if so what (if anything) was in them..? If not then I suggest that should be the next port of call.
Hi, It takes several hrs to get buzzer to go off and it will cool to about 100 deg c in 15 minutes or so, HIdle and neutral. However as soon as you get into it the temp climbs back up to 115 / 120 very quick. Early in the day before everything heats up it manages ok but once all warmed up its a different story. TC outlet at 3rd speed stall was about 50 psi. Yes agree the drops across rad and cooler appear fine and it does not bring Eng temp up (which I expected it would). Cat 30W oil now, yes he tried the 50W for a year or so as well. yes pulled the screens and cut the filter, nothing at all. SOS done as well and its fine on oil that was about 500 smu old. Internals of T/C and oil pump are like new.. The cooling system has run ELC since new but I am going to suggest a complete flush and clean anyway, in case that laminated oil cooler core in the bottom tank has some build up or something. As this problem has slowly got worse over about 2 years. Running out of ideas ! I have read these machines have a small T/C for their physical size and work them hard..
3 months ago was summertime for you, is it still acting the same now that the temps are coming down or has it been used lately? Looks like some nice weather you're having according to your local forecast. In what gear is it working? Is the tractor running back and forth raking into piles or is it working for long distances with a big load?
Hi yes its still getting hot, just takes a little longer in cooler weather. We missed winter last year and looking like the same this year ! Almost 1st day of Winter and its 32 deg c again... He works it in 1st and 2nd, it does a lot of running back and forth with stick rake but it does load up and then it can be pushing quite a distance with a big load. The rake is twice the width of blade and very heavy build, plus it does not have massive teeth either. So yes the little dozer works its arse off !
Therein lies your problem (I think). The mistake often made by operators is to drop the engine speed to low idle after the buzzer goes off, the correct method is to run the engine at High Idle with the transmission in neutral. Under those conditions you should see the TC Out temp gauge fall like a stone back to pretty much the same temperature as the engine coolant, within 30 seconds or less. If it does not then I would suggest that there could likely be some form of oil flow issue to or from the converter to the cooler. That's where I would be investigating next, even though you say you've checked there already.
Hi, yes when early in day and stalling out to do pressure tests etc it will heat up on gauge quick as expected, as soon as you are back in neutral it does drop like a stone (as it should too with a large amount of cool oil in system). Then gradually as the oil and machines gets fully warm the cooling effect seems to drop away. Which is why I am angling back to the cooler itself. Even with the drop I measured maybe it should be more.. Even though its had ELC from day one when you look in the top tank it does not appear that clean.. Appreciate your comments and thoughts ! it all helps..
I hear what you're saying but when you throw the transmission into neutral at HI when the buzzer goes off the rate of drop of the TC out temperature should be the same whatever temperature the engine coolant is at. What will change is that when the engine is warm the rate of fall of the TC out temp will reduce more rapidly as the TC out temperature approaches the engine coolant temperature. With a cold engine it will just continue on falling like a stone for much longer. Regarding the coolant, has it ever been changed or had ELC Extender put in it..? The Extender is to maintain the coolant properties because they degrade over time. Take a sample of the coolant - it should be perfectly clear and a nice pink colour, any cloudiness or tinges of brown and it needs junking. The life of ELC in a machine system is normally put at 5-6 years, so if it's been in for a while I would change it TBH. At the same time why not run some detergent through the cooling system for an hour or so with the machine at operating temperature..? You have nothing to lose. Make sure the detergent is non-foaming (the stuff for a dishwashing machine works really well) and also that the system is well flushed out with clean water afterwards. Fill with pre-mixed ELC (all you can get these days, the concentrate is no longer available) and you're good to go. At least it ticks another box. I know you said you'd looked at oil flow to the cooler, have you looked at the flow coming back from it..? Is the oil flow out of the hose taking hot oil to the cooler the same as the oil flow from the hose bringing the cooled oil back to the transmission..? I would have thought that if the cooler was partially plugged internally that the return oil flow would be visibly less than the incoming flow.
hi Dicks, just a couple of things to think about. in your post you mentioned that you changed the sender and gauge did you actually measure the convertor temperature (infrared doesn't count )if you haven't. here are some cat extracts that may help if you have SIS access you can follow the media numbers for the full articles. the machines mentioned are for different models but use the same sender unit as the D4H. if you don't have SIS access let me know and I can either PM you or email them direct next thing to consider is the fact of internal transmission leakage especially in the clutch and brake area. because this machine has a priority valve the clutch and brake circuits will receive oil before any other components. if there is leakage the priority valve will try and compensate for this loss and will only allow oil to pass to the transmission once this occurs i.e. flow loss to transmission circuits. now this remaining oil has to satisfy transmission demands and until the system pressure can build up to the transmission regular valve setting,no oil will pass to the torque convertor.so in other words the flow through the convertor and also the transmission cooler relies on a leak free path (excluding designed lube paths)from pump to cooler outlet, any oil flow lost internally will reduce oil flowing through cooler and reduce your ability to cool the transmission oil and cause overheating just because your pressure checks are OK? does not mean you have adequate cooler FLOW I would recheck your brake and steering for internal leakage also reducing your convertor outlet pressure to low side of spec can reduce leakage in this area and increase cooler flow The standard machine had a smaller capacity t/convertor compared to the series 111. is it possible that the wrong components have been fitted in the past Mark
Hi, thanks that gives me a bit more to think about and work on, I am unsure about extender but the coolant is certainly not pink. Almost clear with a tinge of pink/red and some evidence of build up on surfaces (suspect..) Yes I plan to run some long term Cat cleaner through it once TC is back in. I will see how that goes and recheck he actual flow in and out as well. I have access to portable dataloggers too so may hook some of them up to see what is the real temp situation.
Thanks for input and tips, yes have SIS and have looked through info. This unit is older and does not have gauge cluster set up like D5/6 etc. We fitted new gauge and sender making sure not to use tape as I found this tip earlier as well. I did some tests on Steering clutch and brakes and also watched what happened on Trans / TC pressure during activation and it appeared to have very minimal pressure drops. As you say we need to understand the remaining flow through T/C.. Its the original T/C and we just had it out, looks like new !
Does this machine have a folded core radiator?
Hi, No its modular and in very good condition. Clean as..
Dicks, re your reply in post #10. I wouldn't bother putting Cat cooling system cleaner through it if the system hasn't been contaminated - and without seeing it it doesn't sound like this one has. Just snag some of your wife's dishwasher detergent and have at it ......
Similar problem I come across on a D6H was TC getting hot very quick while working. Machine would push well and no indication of slipping. TC outlet relief was low, after a lot of checks I found some of the o-rings were damaged in the control valve oil feed tubes and the tubes running to the test points on trans cover, also the priority valve assem was loose, missing the mounting o-rings, just dumping oil back into the trans and not going through the oil cooler. Replaced all o-rings fixed the problem.
I didn't see if you ever tested lube pressure. Lube pressure is a good indicator of cooler flow. When I test a system like this I like test it from a cold start and then see how the lube and torque outlet pressure drop as it warms up. I usually drop the rpm slowly to see at what point I lose lube pressure and where the torque outlet drops below relief setting. At that point I apply steering clutches and brakes to see if it causes any significant change in pressure. Quite often I find a slightly worn trans pump will cause slow heating problems. Testing done at full throttle all the time can be misleading because the pump overcomes its lower output .