JD6620SE transmission oil overheating

[radu]

What could it be? it's below 10 degrees outside. had this happening once in a while but never when it was this cold out. New genuine oil and filters put today, the old oil wasn't black, put a magnet through the old oil and there was a very small amount of very fine metal fillings which i consider normal. The tractor is pulling ok otherwise.

What should i check next?

Thanks,
Radu

 

[Cmoran]

What could it be? it's below 10 degrees outside. had this happening once in a while but never when it was this cold out. New genuine oil and filters put today, the old oil wasn't black, put a magnet through the old oil and there was a very small amount of very fine metal fillings which i consider normal. The tractor is pulling ok otherwise.

What should i check next?

Thanks,
Radu

I had same problem last summer it was caused by the dime valves in the hydraulic slices

 

[Deerefarmer]

More knowledgeable members on here than me,who may know more, but my experience with a power quad overheating was caused by failure of the little air pump in the front of the trans

 

[davidroberts30]

@Phil P

 

[Tractortech]

Now Then..
How many hours has it done?? Has the transmission ever been overfilled ( that can cause air pump failure) . What work is it doing when it gets hot?? Are the SCV's in neutral?? Has anyone done any work on the SCV's recently or added a loader??

 

[JackoTS90]

Is your engine temperature fine? Sometimes when low on coolant and or fluid the temperature rises. This can also cause the oil cooler to not work properly. May be part of your problems? Had this with a 7530.

 

[radu]

it's well above 10k hours (it had a new dash before i got on farm and currently shows 8060 hours but there were at least 3k before the new display), forgot to mention it's a power reverser trasmission. It hasn't been overfilled, not touched the scv's ever and no front loader. it's current job is cultivating with a light weight pigtail cultivator.
Engine temperature is fine.
3-4k hours ago we replaced the clutch disks, haven't touched anything else in that area since.

Radu

 

[Spanner_Man]

Is the engine temp low? Have seen the thermostat split keeping engine temp lower than normal. In turn this does not allow the thermostat for the trans cooler circuit to open causing the backend to overheat

 

[pauld]

I had a transmission light keep coming on some years ago on JD6320

A day on the bale wrapper cured it so I assumed it was sticking valve or something that just needed a good days work. Modern tractors have so many functions that many are rarely used which I doubt is beneficial.

 

[milkloss]

Probably different to a 6920 but I believe they have a thermostat for the oil cooler where the coolant pipes comes out of the block.

 

[Phil P]

There can be a number of contributing things that can affect transmission/hydraulic oil temp. To start with the basics check the coolant is up to the MAX line, if it’s been low it is possible to air lock the LTC (low temperature coolant) system. This cools the charge cooler and oil cooler. There’s a plastic bleeding plug on front bottom of the radiator that can be slackened to let air bleed to the header tank. There’s also a thermostat on the system no4 in the diagram, they do fail occasionally. It is possible to remove the stat from the plastic housing but you’ll need to drain the coolant. Place it looks in some hot water and the pin should move out. Usually pip no1 should get hot as the engine warms up and pipe no10 should be cool and pipe no11 should be hot if the system is flowing.

Some of the other things that can affect oil temp have already been mentioned. You should be able to here the engine and hydraulic pump change note if you dead end a scv, if they don’t change note it could be stuck at full pressure which will soon get the oil hot.

 

[radu]

how could i check if it's the air pump? so far i have ruled out the SCV-s and the oil cooler.

 

[radu]

and we're back to square 1... i haven't used this tractor for serious work since i started this thread until today when i sent it ploughing. After a few hours, the driver calls me and tells me the bleeping oil is overheating again. i had it come in and we removed the coolant and checked the oil cooler for restrictions on the water path. good flow of water through it so that's not it. I also removed the thermostat while the coolant was out. Then i sent it out ploughing again and it stil overheated

It's a power reverser, not a power quad so apparently there's no air pump.

Something else i checked, maybe related or not the scv pressure and it was only 175 bar.

The oil level is at the mark

The oil pipes that go to the oil cooler are both pretty hot, an infrared gun sees them at 80 degrees+, varies drpending on where i measure it.

The coolant line that comes from the oil cooler is also hot to touch, there's no problem with the intake air temperature, so i guess there-s a good flow of coolant


What could it cause it to heat like that?

 

[Phil P]

and we're back to square 1... i haven't used this tractor for serious work since i started this thread until today when i sent it ploughing. After a few hours, the driver calls me and tells me the bleeping oil is overheating again. i had it come in and we removed the coolant and checked the oil cooler for restrictions on the water path. good flow of water through it so that's not it. I also removed the thermostat while the coolant was out. Then i sent it out ploughing again and it stil overheated

It's a power reverser, not a power quad so apparently there's no air pump.

Something else i checked, maybe related or not the scv pressure and it was only 175 bar.

The oil level is at the mark

The oil pipes that go to the oil cooler are both pretty hot, an infrared gun sees them at 80 degrees+, varies drpending on where i measure it.

The coolant line that comes from the oil cooler is also hot to touch, there's no problem with the intake air temperature, so i guess there-s a good flow of coolant


What could it cause it to heat like that?

Does it sound like it’s pumping all the time? Could do with checking the standby pressure, there’s 3 test ports on the priory valve the bottom one is main pump pressure and should be around 30-36bar with nothing been operated and 205 with an scv operated but it’s usually a little bit lower on an se!

Also is it lifting the plough ok? Which hitch valve have you got?
does it look like this-

or like this -

the top one can get a hairline crack causing oil to leak through the system all the time but usually the lift goes lazy.

 

[radu]

there's definitely a change of tone in the pump when i use a SCV and the lift doesn't seem lazy.

I made a new thread a while ago about squeaky steering: https://thefarmingforum.co.uk/index.php?threads/jd-6620-squeaky-steering.348883/ but now it doesn't do it wery often.

Does this tractor have a load sensing pump or a constant flow pump that is pumping oil all the time?

i'm not sure until i get to the tractor but judging by the tractor's serial number, it should be the second hitch valve..

 

[Phil P]

there's definitely a change of tone in the pump when i use a SCV and the lift doesn't seem lazy.

I made a new thread a while ago about squeaky steering: https://thefarmingforum.co.uk/index.php?threads/jd-6620-squeaky-steering.348883/ but now it doesn't do it wery often.

Does this tractor have a load sensing pump or a constant flow pump that is pumping oil all the time?

i'm not sure until i get to the tractor but judging by the tractor's serial number, it should be the second hitch valve..

SE’s have a bit of a funny setup, it’s an open centre pump on a load sensing closed centre (sort of) system. Like I say really you need to check standby pressure and make sure the pump isn’t at full pressure all the time as that will soon cook the oil. Usual it will mane the tractor feel sluggish though if that’s happening. There is an LS valve in the brake pedal that can make the pump go to full pressure but it’s not something I’ve known to be an issue on an SE, although I don’t think SE’s have power brakes.

 

[radu]

there’s 3 test ports on the priory valve the bottom one is main pump pressure and should be around 30-36bar with nothing been operated and 205 with an scv operated but it’s usually a little bit lower on an se!

ok, so plugged in a test gauge and i got these readings:

This was at idle, no hydraulic functions used:

and this was at idle, with a scv leved operated:

Are we getting somewhere?