Disco 2 Automatic gearbox overheating problems

When driving round all is ok. When towing a trailer after a while the red gearbox temp light comes on. So I changed the filter and fluid. I drained 2.5 liters out and put 4.5 liters back in so I take it she was low.
Drove down to London today with the trailer and all was good, until I came off the motorway and hit traffic and there it was again, the little red light. As soon as I got moving again say over 30mph it goes out again.
Same again tonight on the way home fine when moving but hit traffic and there it was again. Changing the oil has really improved the gear changing it’s smoother than an otter in a car wash now, but done nothing for the over heating. Any ideas anyone what I could do next to sort this as I don’t want to do any damage.
I’m going to Stratford upon Avon tomorrow with no trailer so I’ll see how she does tomorrow.

You should change the temp sensor cos it's quite common to wear out and give false readings so better rule it out before thinking to the worst

Temp sensor first. Id' then be looking at the fluid cooler and checking that the fins were not clogged up - if so you can usually reverse flush the fins with a hose. I had immense fun in Romania rodding my cooling fins clear of mud and caked on muck that was causing an overheat...

sierrafery said:

You should change the temp sensor cos it's quite common to wear out and give false readings so better rule it out before thinking to the worst

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Will do. Do you know how hard of a job it is?

chris-the-gerbil said:

Temp sensor first. Id' then be looking at the fluid cooler and checking that the fins were not clogged up - if so you can usually reverse flush the fins with a hose. I had immense fun in Romania rodding my cooling fins clear of mud and caked on muck that was causing an overheat...

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Been to Stratford upon Avon today so 2hrs straight roads then soon as stuck in traffic light back on. After reading your comments I had a look at the rad. Whilst looking for it I noticed one of the cooler pipes that runs under the bottom of the car one of them is slightly crushed. Could this restrict the flow to the cooler and cause the light to come on. But if so why would it go off whilst traveling quicker.

defenderdog said:

Could this restrict the flow to the cooler and cause the light to come on. But if so why would it go off whilst traveling quicker.

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due to highest pressure.... fix that as it seems you found the culprit

It's a good opportunity to change those pipes anyway as they're notorious for coming apart and dumping all the gearbox oil........

defenderdog said:

Will do. Do you know how hard of a job it is?

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Its not to bad of job , did mine in the summer after the light kept coming on . And it fixed it
The sensor plugs in up top just to right of battery, take front offside wheel off and then the inner arch , then theres a small panel behide the ace if you have it ace that is , then its just a case of undoing old one and putting new in. It is a squeeze and oily job especially if you have big hands , oh and i had to lossen off a few bits at top as the plug on sensor was to big to pull down and out , I tied a bit of string on mine so i could pull new plug back up

Vanmancan said:

Its not to bad of job , did mine in the summer after the light kept coming on . And it fixed it
The sensor plugs in up top just to right of battery, take front offside wheel off and then the inner arch , then theres a small panel behide the ace if you have it ace that is , then its just a case of undoing old one and putting new in. It is a squeeze and oily job especially if you have big hands , oh and i had to lossen off a few bits at top as the plug on sensor was to big to pull down and out , I tied a bit of string on mine so i could pull new plug back up

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Thanks Vanmancan. I’ve ordered one and will fit it hopefully next week when I get back from the job I’m on. I’ll let you know the results when it’s done.

sierrafery said:

due to highest pressure.... fix that as it seems you found the culprit

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I’ve ordered the pipes and hope to do the job next week. I’ll send an update once it’s done.

iansoady said:

It's a good opportunity to change those pipes anyway as they're notorious for coming apart and dumping all the gearbox oil........

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Sounds good.