D6R Engine and Transmission Overheating

[FlintHillsDiesel]

Have a friend of mine with D6R 5LN.
He went through entire engine cooling system, water pump, radiator, thermostat.
He wanted me to look at it after that, when talking with him, he said that after engine gets hot, the transmission gets hot shortly after.
Told him its likely the transmission overheating and causing the engine overheat as secondary effect.
I work mainly on Deere equipment not as familiar on theses machines.

With going through some older threads on here, we checked the Priority Valve, and it is switching between Priority and Normal mode correctly per the pressure chart.
Priority valve - 140 psi operating temp, PB on, low idle
400 psi PB off neutral low idle
140 psi - high idle PB off
140 psi - high idle service brake on

Checked the brake pressure on the left pressure tap (right side tap is missing and didn't have time to swap them).
Left brake pressure - 390 psi.
Almost 0 when service brake applied.
Too muddy around for me to run it. Friend said it will roll to a stop, it doesn't act like the brakes are dragging/warped.

Checked transmission pressure:
Transmission system pressure - 390 psi low idle - PB On
395 psi low idle PB off
415 psi high idle PB off
410 psi high idle PB off service brake on

TC Inlet - Initial reading at 100 psi slowly goes down 85 psi as fluid warmed up more I assume - high idle PB off
83 psi at 175'f converter outlet to cooler.

TC Outlet - 70 psi high idle, PB off, neutral
55 psi forward 3rd gear stall, 1650 engine rpm

During stall test, the transmission temp would heat up very fast. From about 180'F to the beginning of the red happens in about 12 seconds.

I did not pay attention to how fast it cools off after.

Friend went and ran someone elses machine he knows thats a D6R LGP from same era.
Had him do a stall test after everything was at normal operating temp and said it took about 35-40 seconds to get from normal temp up to the beginning of the red on his transmission temp gauge.

At this point I'm fairly sure the torque converter is causing excessive heat. But wanted to double check to see if I am missing anything.
Can the trans pump cause that much heat that fast?
Did not get the TC inlet relief checked when oil was cold - might be wrong but I don't think this is important for the symptoms?
The torque converter outlet speed sensor was also broke apart, fixed that and cured the only active code I could see, but also think is irrelevant for the symptom as was no slippage code after fixing and doing stall test.

Also have not pulled the screens yet. Was a muddy mess that day and spent 2 hours cleaning out the compacted dirt inside the belly of the machine. What fun that was.

Thank you!!

 

[Nige]

Reading the story, I think you're right that the powertrain is what's overheating the engine because it's simply producing too much heat for the cooler/radiator to get rid of.

How many total hours on the machine.? Has the converter or transmission ever been out before.?

Couple of things. The 390psi you measured I assume is pump pressure.? P1 & P2 pressure measurements would also be good.
A good gauge of the speed of transmission clutch engagement is how fast the driveshaft between the converter output and the transmission input stops when you engage any gear at idle speed. It should literally stop dead.

Attached is the T&A for a 5LN powertrain including the location of the pressure taps. Can you do all the measurements and report back with findings please.

EDIT: Did you shoot any coolant temperatures at the radiator inlet/outlet.? If not it might be a good idea.

 

[Nige]

Did you shoot any coolant temperatures at the radiator inlet/outlet.? If not it might be a good idea.

Also oil temperatures at the inlet & outlet of the transmission cooler while you're at it.

 

[tctractors]

Flint Hills, you just might need to back up some and double check firstly the radiator is not caked in trash, so open the right hand engine door as sat in the seat then take a work light and look hard at the bottom and top of what is in front of the fan, then if it all looks clear I would order an oil cooler gasket kit and engine oil filter, then strip down the cooler pack, that is the oil to water heat exchangers for the engine oil and transmission oil, the water flow is from the pump through the engine oil cooler then on to the trans cooler, the water flows down one half of the cooler then turns at the bottom back up through the other half and into the cylinder block, this task is important to do even if the torque is at fault, on the transmission pressure testing on the R series I start by removing the plate bellow the fuel tank and the guard plate over the plug connection also the back plate that lets you see it's innards, the plug on the left by the electrical connection is P1 pressure or your Priority Pressure that off top of my head is 420/425 psi this is what lets your brakes off, the transmission pressure on the modulation valves is usually 1st speed 320 psi, 2nd 370 psi, 3rd 370 psi, forward and reverse are 320 psi, your testing of the priority valve that you get to via dropping out the belly plate was correct but at 410 psi I would adjust it up a tad on that valve by the drive coupling, there is a stall test you can do but avoid using the low speeds for this as in 1st gear you can drive through the brakes, 2nd gear has only 2 plates but 3rd has 3 frictions and can take more hammer, the torque converter usually fills the case with excess oil when it fails, if it has drive it up on timber baulk's as it comes out from the bottom chap.

 

[Nige]

Also have not pulled the screens yet.

Be aware that there are 3 of them. The one in the transmission case and the external one in the powertrain oil lines are obvious but the small one built into the fitting in the converter scavenge line not so much...... If the converter housing is flooding because it cannot be scavenged correctly the result will be heat. Probably worthwhile checking at the same time that the scavenge section of the pump is operating up to snuff.

 

[FlintHillsDiesel]

Reading the story, I think you're right that the powertrain is what's overheating the engine because it's simply producing too much heat for the cooler/radiator to get rid of.

How many total hours on the machine.? Has the converter or transmission ever been out before.?

Couple of things. The 390psi you measured I assume is pump pressure.? P1 & P2 pressure measurements would also be good.
A good gauge of the speed of transmission clutch engagement is how fast the driveshaft between the converter output and the transmission input stops when you engage any gear at idle speed. It should literally stop dead.

Attached is the T&A for a 5LN powertrain including the location of the pressure taps. Can you do all the measurements and report back with findings please.

EDIT: Did you shoot any coolant temperatures at the radiator inlet/outlet.? If not it might be a good idea.

Machine has 26,000+ hrs
Unsure on any previous repairs.
Owned for about a year and had this problem when he bought it.
Has put on roughly 1000 hrs since bought.

Is there temp sensors for inlet and outlet of TC or does this need monitored manually?
To Do:
Readings on inlet and outlet of Radiator
Reading of inlet and outlet of TC
My pressure reading was Transmission Main Relief Valve (E) on your Tap Location page.
Pull and check 3 screens.

What would preferred way to check TC housing flooding, or scavenge pump operation this before or after running dozer?

What pressures does P1 and P2 refer to?

Thank you for your time!!

 

[Nige]

Machine has 26,000+ hrs
Unsure on any previous repairs.

At least we know where we stand. I would hope that the transmission & converter have been overhauled before but with that number of hours they are most likely ready to be done again.

What pressures does P1 and P2 refer to?

I had it in my mind that this was an old-style transmission but it is an ECPC (Electronic Clutch Pressure control), so P1/P2 (speed & direction clutch) pressures do not apply. As you were.......

Reading of inlet and outlet of TC

I was referring to the oil temperature at inlet/outlet of the powertrain cooler to check for a possible plugged cooler. Requires an infra-red heat gun.

Pull and check 3 screens.

This should be your first priority I would say. Depending on what you find in them further testing might be unnecessary. Take photos of what you find in all 3 screens.
Before draining the oil I'd suggest to do the transmission test engaging each F/R gear at idle and observe how fast the drive shaft stops.
When you pull the scavenge suction line off the bottom of the converter take note of how much oil drains from the converter housing and report the results.

Please post a full Serial Number. It appears as thought there are differences regarding Part Numbers of critical powertrain componens such as torque converter, transmission, oil lines, etc, throughout the 5LN-prefix range. It may have a bearing in the problem, maybe not.
With that in mind it might be an idea to get the Serial Numbers from the transmission and converter as well, just to check if they are the originals from when the machine was built.

 

[FlintHillsDiesel]

At least we know where we stand. I would hope that the transmission & converter have been overhauled before but with that number of hours they are most likely ready to be done again.

I had it in my mind that this was an old-style transmission but it is an ECPC (Electronic Clutch Pressure control), so P1/P2 (speed & direction clutch) pressures do not apply. As you were.......

I was referring to the oil temperature at inlet/outlet of the powertrain cooler to check for a possible plugged cooler. Requires an infra-red heat gun.

This should be your first priority I would say. Depending on what you find in them further testing might be unnecessary. Take photos of what you find in all 3 screens.
Before draining the oil I'd suggest to do the transmission test engaging each F/R gear at idle and observe how fast the drive shaft stops.
When you pull the scavenge suction line off the bottom of the converter take note of how much oil drains from the converter housing and report the results.

Please post a full Serial Number. It appears as thought there are differences regarding Part Numbers of critical powertrain componens such as torque converter, transmission, oil lines, etc, throughout the 5LN-prefix range. It may have a bearing in the problem, maybe not.
With that in mind it might be an idea to get the Serial Numbers from the transmission and converter as well, just to check if they are the originals from when the machine was built.

Thank you very much for your time again.
Will be few days before I get back to his machine.

 

[tctractors]

The Torque converter screen has a big mesh and would only stop a ball bearing, it hides behind the low level pipe to the right of the case, the comment was "The Engine gets Hot then the Transmission gets Hot" do you think the engine is not cooling correctly and as its not cooling it gets the Transmission hot???

 

[FlintHillsDiesel]

The Torque converter screen has a big mesh and would only stop a ball bearing, it hides behind the low level pipe to the right of the case, the comment was "The Engine gets Hot then the Transmission gets Hot" do you think the engine is not cooling correctly and as its not cooling it gets the Transmission hot???

My thinking was the transmission overheat temp is 40'F higher than the engine, so didn't think the overheating engine would cause the transmission temp to go that much higher.
But I will definitely be checked inlet and outlet temps at the coolers and radiator.

On the engine oil and trans oil coolers can you thoroughly check them once out or do you send them out to be checked?

Thanks

 

[Nige]

But I will definitely be checked inlet and outlet temps at the coolers and radiator.

I would say check the radiator first. If it is in good condtion and working as it should the temp difference between inlet and outlet should be somewhere around 18 DegF/10 DegC.

 

[tctractors]

You are looking at the water tubes in the coolers, it's easy to strip them and clean them out with a thin rod, if the load is removed from the engine how long does it take the 2 temps to come down, that is the engine water and transmission oil at High Idle.

 

[Queenslander]

I thought I would post these photos here as you were all discussing oil coolers.
Our 7H transmission temps steadily rise and stay there, regardless of load and ambient temp.
Engine temp would rise throughout the day, drop with reduced load, rapidly at idle…transmission would only drop 5c after 15 minutes of idling.
Ran some Quickflush through the system and pulled the coolers (aftermarket) this afternoon.. they look clean enough.
My thoughts are that there isn’t enough coolant passing through the tubes of the cooler.
When looking at the tubes of the genuine reman unit we are putting on, there is approximately 2mm clearance between the end of the tubes and the horizontal divider of the manifold.
On the old aftermarket unit the clearance is around 4.2 mm.
On edit…the thickness of the gasket has to be added to these measurements as well.

 

[Queenslander]

So, new coolers fitted and tractor back to work today.
Transmission much cooler, engine cooler, both temps drop quickly with lighter load or idle now.
A good 10c temp drop across the cooler.. before there was next to none.
We were fortunate have had a new genuine cooler to compare the old one with otherwise we would likely have called it good and refitted.

 

[JAJ]

So, new coolers fitted and tractor back to work today.
Transmission much cooler, engine cooler, both temps drop quickly with lighter load or idle now.
A good 10c temp drop across the cooler.. before there was next to none.
We were fortunate have had a new genuine cooler to compare the old one with otherwise we would likely have called it good and refitted.

Very interesting!!! I have seen that very same gap you speak of and wondered how it would not cause some coolant to bypass. The reason for the gap that I dreamt up was that if the tubes blocked it would still allow some coolant though the engine. My instinct was there should be no gap there so a smaller gap would have to better, very good find. I have never had both side by side to compare like that, so well done.
The very interesting part is the huge difference between the genuine and the aftermarket! I wonder if aftermarket option works ok with reasonable ambient temps or if that would always cause problems?
Was there any blocked tubes in the old one, anything else changed, or do you think it is all down to the extra gap??

I’m thinking I may have to check the ones on my D6H and 966G now to see if they are genuine or aftermarket!!

 

[Nige]

So, new coolers fitted and tractor back to work today.
Transmission much cooler, engine cooler, both temps drop quickly with lighter load or idle now.
A good 10c temp drop across the cooler.. before there was next to none.
We were fortunate have had a new genuine cooler to compare the old one with otherwise we would likely have called it good and refitted.

A perfect illustration of “just because it fits in the hole doesn’t mean it will work the way the original design did”.

 

[tctractors]

You need to measure this tube hight detail from both ends of the cooler, it will always be different and the cooler will fit any way, it's only the end casings that are different.

 

[FlintHillsDiesel]

 

[FlintHillsDiesel]

 

[FlintHillsDiesel]

TC Inlet Relief oil cold was 130 psi.
TC Housing suction line screen was clean except for couple small chips of paint sitting there. Only drained couple quarts.
Magnetic screen - the screen was very clean, magnet had what seems like normal amount of fine metal on it.
Did not pull the rear suction screen on the PS housing, as the cover and bolts are all messed up, and looks like it will drain that housing?
The pictures above are while dozer is being worked, the overheating happens very slowly, making it hard to determine whats going on. The left engine sheet metal was removed for the pictures which seemed to make it take longer to get hot.

A retired CAT technician had gone through the radiator already and installed new cores into it.
The fan speed was also measured at 1258 rpm at full throttle - 2200 rpm engine speed.