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Is my auto box knackered or does it need better cooling??


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I have a 1996 discovery es 300tdi, currently living in spain 12 miles from coast but 910 metres above sea level, the transmission hot light comes on approximately half way up the hill (500 metres in altitude)when towing a 1 tonne trailer (the light comes on at 650 metres without the trailer). The temperature is usually about 30 degrees C. Is this normal, I have changed transmission oil but not much change. Do I need a larger oil cooler or is it likely a transmission overhaul? The red light doesn't go out until i get home and let it rest, the last mile having 200 metre height gain and no tarmac.

Any help much appreciated.

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My 96 Tdi does the exact same thing, mainly on the beach and very steep hills. The auto was only rebuilt 12 months ago.

I'm fitting a larger oil cooler this weekend and flushing out the pipes so I'll let you know how it goes.

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I have the same Disco as you and have frequently towed heavy twin axle4 trailers to our house in Spain which is 4000ft above sea level, and never had a problem with over heating also towed across the Alps a few times and never had a problem either. Would suspect the oil cooler or pipes are slightly blocked, or at least i hope for you thats what it is cheaper than a new box



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Okay, fitted the new transmission cooler and did a run up Stockton beach yesterday.

Still overheating but no-where near as bad as it was though it was only getting the air through the grill as I drove to achieve the cooling effect.

Discovered upon getting home that the twin thermo fans come on when the air conditioner is running (never got around to re-gassing the aircon since I bought the car so it never gets turned on).

With the fans running the heat dissapation was markedly increased (stuck my hand behind the cooler and could feel the heat getting drawn out).

So my next mission is to wire in a dash-mounted switch to run the fans independant of the aircon and make a shroud/cowling from the cooler to the fans to increase the airflow through the fins.

Hopefully on my next trip to the beach I can just flick a switch to start the fans up and problem solved.

Soon as I figure out how to do it, I'll post photos of the new cooler and bracket that I made to mount it.

Hope this helps

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