Discovery 2 td5 auto gearbox over heating

Hi all I recently purchased my first land rover a 2000 discovery 2 td5 auto. Very excited to be a lr driver , only being on the road with it a couple of days and hit my first problem. My auto gearbox is over heating after 15 minutes of normal driving the auto transmission temperature light comes on and it doesnt feel as good as it did from cold still pulls reasonably well.
I pulled over to let it cool and crawled under and felt the trans oil cooler and it was red hot both sides almost to the point you couldn't touch it. After nursing it home i checked the level in the gearbox according to online instructions but only put about 500 ml before it trickled out. I didnt check the condition of the oil in the gearbox , just topped it up.

I'm planning on changing the box filter and oil , taking off the cooler to flush it this weekend.
My question is there anything else I can check , I know there is a sensor on the oil cooler but as the cooler is very hot I think it's doing its job.

I appreciate any help, many thanks.

Make sure the oil sump is clean on the outside and that it’s not been painted. Part of its function is to help cool oil too so if it’s been painted a dark colour it can retain more heat, but a oil flush should do the trick. ATF is a high detergent oil so worth draining the oil and then filling it up, running it and then draining it again, changing the filter this time and then re filling, as one single drain will leave behind a few L of oil, so you don’t want that and the crap going through new filter, but a couple of drains should do the trick

baronvonprepper said:

Make sure the oil sump is clean on the outside and that it’s not been painted. Part of its function is to help cool oil too so if it’s been painted a dark colour it can retain more heat, but a oil flush should do the trick. ATF is a high detergent oil so worth draining the oil and then filling it up, running it and then draining it again, changing the filter this time and then re filling, as one single drain will leave behind a few L of oil, so you don’t want that and the crap going through new filter, but a couple of drains should do the trick

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OK to just to be sure I shouldn't change the filter the first time , just drain and re fill , run for a bit, then drain drop the pan change filter and gasket then refill .
How long should I run it after the first oil change to do it again.

Do you thing the cooler or pipes could be blocked, Should I remove the cooler first or wail until after to see if oil changes sort it out.
Would you recommend a auto gearbox flushing additive to helpay clean things

Many thanks

Part of the oils "JOB" is to enhance cooling function and reduce high operating temperatures.

Try giving it a good service and record the colour and smell of the old fluid..

Henry_b said:

Part of the oils "JOB" is to enhance cooling function and reduce high operating temperatures.

Try giving it a good service and record the colour and smell of the old fluid..

Click to expand...

OK how much oil can expect to get back in the gearbox. I know you can't drain all of it out, and it's dry capacity is 9.8L
But if I buy 10L of oil would that be enough for two flushes.

Just drop what's in the sump, around 4.5 litres and change the filter..



You could drop the new oil after a few hundred miles and this'll get a good quantity of the old stuff out.

Dex 3 for the hp22.

Henry_b said:

Part of the oils "JOB" is to enhance cooling function and reduce high operating temperatures.

Try giving it a good service and record the colour and smell of the old fluid..

Click to expand...

its also the reason autos get hot ,as drive is produced by using oil pressure to drive a turbine theres an energy conversion which my its nature produces heat as not all energy can be converted,lock up of the tc removes that as it makes direct drive not through the turbine,another cause of excessive heat is clutch slipping which is shown by black oil

NumberoftheBeast666 said:

OK to just to be sure I shouldn't change the filter the first time , just drain and re fill , run for a bit, then drain drop the pan change filter and gasket then refill .
How long should I run it after the first oil change to do it again.

Do you thing the cooler or pipes could be blocked, Should I remove the cooler first or wail until after to see if oil changes sort it out.
Would you recommend a auto gearbox flushing additive to helpay clean things

Many thanks

Click to expand...

Correct that’s what I would do. The new oil put in will be more likely to dislodge any crap in the system, no point clogging up a new filter with that.

However filters are cheap so you could do an oil and filter change and then a few hundred miles and then repeat.


I would leave the pipes and cooler alone for now, new oil in the system should do the trick

baronvonprepper said:

Correct that’s what I would do. The new oil put in will be more likely to dislodge any crap in the system, no point clogging up a new filter with that.


However filters are cheap so you could do an oil and filter change and then a few hundred miles and then repeat.


I would leave the pipes and cooler alone for now, new oil in the system should do the trick

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Thank you guys for all the advice, I will get it done this weekend and report back.

Many thanks

Hi all well I changed the automatic transmission oil and filter today. The oil was a dark brown colour not black and didn't smell that bad. After a test drive it's still pulling through the gears fine. But the overheat light still comes on in traffic and oil cooler still hot.

My next question how hot should a oil cooler be. I have also noticed that my viscus fan can still spin freely even when hot. Could this be the cause ? Engine temp always seems to be just over half way even cold temperatures..

Any advice much appreciated. Thanks

Get it plugged in to Hawkeye / nanocom to check engine temps. Although I’m currently running without a fan due to doing some work and have no issues. Remember that one oil drain only empties about half the capacity, so there is lots of old oil still in there

Thanks I will get it done. I'm reluctant to think it's gearbox fault as it pulls so well and the oil was not that bad. Is it safe to keep using it .

I know the oil cooler is there to cool things down and it does get warm but how hot is to hot. I can put my hand eather end and keep it there its hot but not scolding. Maybe it is a faulty sensor.

Also silly question but I've removed all the under bumper guards , would this affect air flow to oil cooler

Nah that won’t be an problem with airflow.
Might be worth seeing if roads are dirty as that won’t be helping cooling either. Could be caked in mud and all sorts