300tdi Auto box problems

Hi everyone,
I towed my caravan with my disco 300tdi auto a few weeks ago, after about 30 miles it started struggling a bit, with only 5 miles to go i carried on.... when i got to the site the gearbox absolutely stunk and it had gotten that hot the kickdown cable had melted.
I left the caravan on site and changed the cremated oil. Only problem is only 4 litres came out but i thought it held 8 litres?? I filled it up thinking it was just very low but it only took 4 litres so no oil loss.
Is there a knack to emptying all the oil or is there perhaps a blockage somewhere?
Should i flush out the oil cooler or even replace it for a better one?
I intend to do more towing and a lot further but daren't with these problems.

That all u can drain 4 litres the remainder is in the torque converter, so after u have replaced your fluid drive for 50 miles or so and drain and refill again this will dilute the fluid even further that was remaining in the torque converter, no need to touch the cooler unless u think there's an issue with it.

You could also change the filter screen and check its condition at the same time.

The only way to replace all the fluid at one time is to get it plugged into a machine that will do it for you, but you will have to find a LR garage that has the machine to do it.

you shouldnt need to flush cooler unless a clutch pack has burned ,which would show with blackened oil, in which case any oil changing is fruitless

Thanks for the replies, i changed the filter screen when i changed the oil, i'll change it again this weekend.
The oil wasn't blackened.
Only reason i mention the oil cooler is because it overheated after just a short drive.

jroo19 said:

Thanks for the replies, i changed the filter screen when i changed the oil, i'll change it again this weekend.
The oil wasn't blackened.
Only reason i mention the oil cooler is because it overheated after just a short drive.

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Did u see the warning lamp illuminate, u should have stopped and waited for it to extinguish before carrying on, your lucky that only the cable has melted.

there is a temp sensor in the oil cooler pipe, it might be worth taking it out and checking it works, also check the over temp light is working.

discool said:

Did u see the warning lamp illuminate, u should have stopped and waited for it to extinguish before carrying on, your lucky that only the cable has melted.

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No warning light came on.

hifly said:

there is a temp sensor in the oil cooler pipe, it might be worth taking it out and checking it works, also check the over temp light is working.

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How do i check if the sensor is working?

jroo19 said:

How do i check if the sensor is working?

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Good question easer to test the electrical circuit, just remove and ground the purple/black wire at the switch to test the lamp..

I did away with the sensor completely on mine and fitted a temperature gauge instead.

discool said:

Good question easer to test the electrical circuit, just remove and ground the purple/black wire at the switch to test the lamp..

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Ok thanks i'll try that tomorrow.

Mark L said:

I did away with the sensor completely on mine and fitted a temperature gauge instead.

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If i did that what is normal running temperature and whats the threshold for too hot?

I can't remember exact numbers without looking at the gauge, but it generally runs in the blue in this country.
Morocco was a different story. Low range off road in the Sahara saw in right up near the red...

That said, I'm running an Allisport custom gearbox oil cooler which is 3 times the size of a standard one.

to test the sensor attach a multimeter to the top connection and the body set it to OHM's it should read infinity then warm up the end of the sensor and the resistance should drop to almost 0 OHM's.

Don't know what temp it should change at but i would of thought less then 100 C so boiling water should make it switch.

Mark L said:

I can't remember exact numbers without looking at the gauge, but it generally runs in the blue in this country.
Morocco was a different story. Low range off road in the Sahara saw in right up near the red...

That said, I'm running an Allisport custom gearbox oil cooler which is 3 times the size of a standard one.

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Nice!!

If i can't get any joy from the sensor i might go down the oil temp gauge route, cheers guys.

hifly said:

to test the sensor attach a multimeter to the top connection and the body set it to OHM's it should read infinity then warm up the end of the sensor and the resistance should drop to almost 0 OHM's.

Don't know what temp it should change at but i would of thought less then 100 C so boiling water should make it switch.

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cool, i'll try that too, thanks.