Hi Team, I have a D7R 3ZR that has had over heating issues for a while when the Ambient air temperature gets over 32 deg C. The Steering and brake controls unit has been removed and resealed and OEM valves installed, transmission wiring harness and speed sensors replaced as was locking in gears causing trans to lock up. (Customer prior to us looking at the transmission faults fit aftermarket Trans pump) Didnt fix problem. Whilst transmsission was out rebuilt as No4 clutch pack was burnt out ( raking in this gear) and No 5 rotating group seal carrier replaced(had previous failure problems with these) New clutch modulation solenoids Cat parts fitted. New planetary gears, bearing kit, Seal Kit Cat. After fitting the transmission replaced ECM as was out of calibration and couldnt be re flashed. Customer complained of Trans running hot. Replaced mulitple T/C sensors and test guage against infra gun and Thermal imaging camera all close. High converter temps 125+ degc working for and excessive leakage (5.5Litre) Stall Hot oil for a D7R T/C so removed and resealed but nothing excessively worn. Trans cooler replaced( aftermarket) Carried out additional tests to rule out Radiator/ Stall speed issues although couldnt find specs so going off past dozers 1660rpm which seems slightly low. 9 Deg C diff from Trans cooler inlet/outlet Brakes felt to be dragging but had to tell on sandy soil so performed multiple brake touch up calibrations to get the feel right. Trans temp @ 80 deg, Test similar conditions with a D7R 5MR down less gradient decline and machine rolled easily. Pressure tested brakes both between 390 and 400psi hot oil. Removed steering clutches and brakes but didnt find warped discs or anything conclusive however did note when removing LH Scab found LH inner axle very hot compared to RH axle Noticed the housing when checked with thermal imaging camera was 10deg C hotter on LHS Carried out another test with machine running Hot oil PB released could not turn the F/D with a 5ft bar on Segment bolt LH but could just turn on RH. Removed Steering and brake block again to see if something was over looked and couldnt determine any faults. Checked voltage to steering and brake solenoids to confirm correct but still have been able to to resolve the problem. Any help would be greatly appreciated.
Maybe post your Serial number complete, and some of the resident D7R experts may chime in. I am guessing that the rad and front end cooling is all okay at top and bottom rad hose. Simon C
I wouldn't go as far as to guess. I see nothing whatsoever regarding the cooling system. Also it's interesting that the problem only occurs when the ambient temp is high (32 DegC = 90 DegF) which is the very point at which cooling systems that are not in 100% optimum condition tend to run out of puff and wave the white flag. Requires infra red heat gun data from radiator inlet/outlet hoses, plus (if possible) a thermal image of the radiator that might show something interesting, or rule it out, as the case may be. Radiator cores OEM or aftermarket.? Does the system lose coolant over time.? What type/brand of coolant is it running.? What temp is "normal" for the cooling system.? Fan drive pulleys/tensioner condition.? Fan belt condition.? Fan spider condition.? Stupid question - is the fan installed the correct way round.? Water temperature regulator OEM and correct Part Number; replaced recently.? Fan cowlings all in place with rubber baffles intact and not torn.? See the illuistration below. The Pipe #5 directly above the temperature regulator should have a Part Number cast into it. What is that number.? Straws and camels backs spring to mind. 9 DegC temp drop across transmission cooler (I'm assuming at normal machine operating temperature but TBC) seems low to me, but I may be wrong. That will tell us if it is equipped with an attachment High Ambient temperature cooling package. If it was originally sold into Australia that is always possible.
I wouldn't go as far as to guess. I see nothing whatsoever regarding the cooling system. Also it's interesting that the problem only occurs when the ambient temp is high (32 DegC = 90 DegF) which is the very point at which cooling systems that are not in 100% optimum condition tend to run out of puff and wave the white flag. I was hoping more than guessing, as all cooling happens in the front end, everything else can get changed and if radiator, cooling system from fan is no good it will still overheat. That is what I meant. Simon C
This is a old school way of checking for overheating torque 3rd gear stall till you hit red line on gauge put transmission in neutral while still at high idle repeat till you get to normal operating temperature once you have everything warmed up third gear stall till red line this time do not go to neutral leave transmission in 3rd cut throttle to low idle you should see gauge slowly moving towards normal It’s a good check because you are at low cooler oil flow sometimes a pump at high idle will overcome leakage in system
A slight variation from the above that we used to use was, with everything at normal operating temperature, stall the transmission in 3rd speed until the high converter outlet temp warning came on. Then without easing off the revs, flip the transmission into neutral and watch the coverter outlet temp come down. If the needle on the gauge falls like a stone it is a positive sign.
That is exactly how we tested all the big Cats where I worked, and the torque temperature does drop very fast when shifted to neutral. On one newly acquired one it would not, so they pulled the cooler apart and it was mostly plugged off from some failure they were not aware of. Once cleaned it was all good. The D7R's at Syncrude in Fort McMurray had all the rads on the roof with Electric fans to keep them clean in a dirty environment where dust was blowing into the units. Simon C
I did not see any comment on the engine oil cooler being checked for pegging up with crap, the water has to go through this to get to the Trans' cooler, also was the pressure control (Modulation Valve) checked for correct spec' at the different speeds, that is the valve just by the spider shaft bolted to the transmission vertical face, D 7 H and R series were always in trouble with Vee Belt or fan hub bearings also able to eat belt pulley's, the front cooling pack also needed a lot of maintaining.
A long long time ago we would go to neutral but we found leaving it in third and cutting the throttle was a more precise test as it kept high pump flow masking leakage in the system
When checking the all temperatures of the cooling system and transmission I have used Cat ET and infra gun to confirm check differences. Testing of Transmission and cooling system Temp Engine@ Sender unit 98 95 98 96 Radiator Top 91 94 92 Radiator Bot 94 87 87 Waterpump 89 90 86 T/C Cooler inlet 111 108 110 105 TC Cooler outlet 101 96 99 92 Transmission (Rear house) 102 100 98 All these temps were read Late 2024. The radiators had since been removed( I think aftermarket) cleaned and reassembled. Thermostat was replaced and bleed valve also ( cant confirm as customer did this work. I adjusted the fuel pump timing which was a bolt hole and a half retarded. Engine now sits on 82 degrees for 4-5 hours 2 needle width over half and T/C guage (T/C Outlet) which is where the operator gets the indication of trans temp comes from gets up to a needle width below red line. Roughly 122 deg C. Green coolant OAT is used in the cooling system mixed 50/50 with rain water. Since these inital test were complete i mentioned to the customer that he needed to check/replace injectors as i could hear a miss. Since then it dropped an injector tip and engine rebuild was performed by the customer. Since the temps are just getting up in Australia i am starting to see the problems again. We initally looked at this machine in 2020 and did fan pulley upgrade 4165507 PULLEY ( Cat) and various undercarriage work. Havent had any heating issues for 2000hrs until trans started to lock up. Nige, The Pipe 5 still has the restrictor in it but not sure of the Part # i havent replaced it. Fan is installed the correct way, with no coolant loss or signs of engine overheating until trans temp reaches over 110 C. When walking the machine it gets hot travelling to the next Job. S/N 3ZR00719 Machine has 31000hr or so on it. ( According to the hour metre) Pittsburgh I currently do the same tests as mentioned and check the cooling capacity of the Oil cooler in the trans circuit. Stall @ 62 trans temp 1660rpm 62 deg trans to hot on T/C 46 sec 68 deg Trans to hot on T/C 42sec T/C Redline to 1/3 on guage 2.15 min (Idle) T/C Redline to 1/3 on guage 40Sec ( 1500rpm) T/C Redline to 1/3 on guage 30sec ( 1800rpm) T/C is at 60psi Stall The trans pump was stripped inspected and refit as was a cat pump so replaced the customer fitted aftermarket option. Hope this helps
It was replaced Tony. There is a lot of info there. I had to read it quite a few times before I found it. The fact the replacement cooler was aftermarket still raises a red flag for me. EDIT: My apologies, it was the transmission oil cooler that was replaced not the engine oil cooler. As you were........
Get it out ASAP would be my advice. That plus replacing the temperature regulator with a genuine OEM. Part Number 111-8010. Spec of that regulator is fully open at 91 DegC, not the 82 DegC you are seeing. Another question mark. I seem to recall a battle a while ago with what I'm sure was a D7R also in Australia with powertrain overheating that turned out in the end to be low flow out of the top of the thermostat housing. i will see if I can find it. See comments below. Those number to me potentially indicate a problem. You should be looking for a temp difference inlet to outlet of bang on 10 DegC between coolant inlet and outlet at the radiator if everything is working as it should. If you can get hold of one then a thermal imaging camera (apps are available these days to work with the camera on your phone) might give some insight into the radiator condition regarding flow through it and show up any hot spots.
There may have been another (third) D7 as well . 32 c is a third of the way to boiling and an aged cat has no spare cooling capacity . Guy I've met put an extra radiator in front of his existing one on a D4 hightrack , fixed his problem . Over heating could be a reason why they come up for sale as I've seen one here (NZ) advertized for sale with a new radiator .
Is this Tractor fitted with the 3306T.A. motor???
Affirmative. Jacket Water aftercooled. 10Z-prefix 3306 engine.
Yes it is a 3306 TA. I will confirm the cooling temps as not near the machine, and get some thermal images. These results ( Listed)were prior to removing and cleaning radiator/cooling system repairs which customer undertook. I know on the D8R there is an option for higher trash flow cores that have greater capacity but havent investigated the options for this machine. I am still concerned however about the brake drag/T/C temp high when driving but if you suspect the issue is elsewhere i will divert my thoughts.
i don't think it should be a case of having to divert your thoughts based on what other people including myself have suggested. It's more a case of keeping an open mind and doing a proper box-ticking diagnostic procedure by slowly eliminating possibilities until what remains MUST be the root cause of the problem. i think @epirbalex said it very well a few posts up - "an aged cat has no spare cooling capacity". The issue could be the sum of a dozen different things, none of which alone would cause a problem, but when added together are sufficient to take the edge off cooling system efficiency to cause overheating under certain specific conditions. Also don't forget what was mentioned by @tctractors above to look at the coolant flow through the engine & transmission oil coolers on your machine. If as he suspects the coolant flows through both then partial plugging of the coolant side of the engine oil cooler could significantly affect the efficiency of the transmission oil cooler. I already mentioned above that I don't think a 9 DegC temperature drop of the transmission oil across the cooler is sufficient, but I may be wrong. See the attachment. My honest opinion is that you really shouldn't move past the cooling system until you have gone over it with a fine tooth comb and eliminated the remotest possibility that it could be the cause, or at least part of the cause, of the transmission overheating problem. Question: Are the radiator cores OEM Cat or are they aftermarket.?
If I remember right their are taps for brake pressure on top of finals it would be interesting to see what kind of pressure you have there from what you said about axel being hot, brake dragging could cause a lot more heat than it could take care of
The chance of getting those plugs out are next to Zero on an old girl like this, you don't really need to test at that point there is pressure test ports on the brake control (Diff Steer) that will show if a brake seal has failed, if the Tractor is standard steer you can still avoid those rusted out plugs to work out if the brake and clutch are good.
if the engine oil cooler has not been stripped and cleaned it's a waste of time, a good tip to assess the cooling system is to firstly point the red dot of the heat gun at the top side of the engine oil filter watching the temp increase then drop fast as the regulator opens.