Hi, I hope that this may be a last question for a while !!!

About two weeks ago the gearbox oil cooler fan started running as soon as the ignition switch is turned on. So I got under the car to see what may be the problem, and I found two cylindrical type sensors screwed onto one of the supply pipes. But, despite hours searching, I have not been able to find any information about replacement sensors.

I have found a couple of different part numbers, STC3338, and NSC101060, or FF012060, but these appear to be flat sensors which screw straight to the side of something, perhaps the gearbox. There is a few bits online about about the gearbox oil cooler fan running all the time but nothing about the parts needed to solve the problem.

I appreciate that no many people here have 2.5 DHSE's but perhaps someone may have found a solution to the problem. I am including a picture, from somewhere online, which shows the same set-up as my car uses, and it can be seen that there are two round cannister type items on one of the pipes. One seems to be to switch on a dashboard warning light, and the second seems to be the fan switch. I think that it is this switch that is stuck closed, keeping the fan on permanently.

Pierre3.

They aren't the temperature sensors, they are the AC pressure and trinary sensors that live in that area. If you look at the picture closely, you can see that the alloy pipe is going into the top of the receiver dryer.

Of the part numbers you quote, STC3338 is a thermostat but the other two numbers are for a sensor which, as you say, is a flat sensor with 2 holes in it looking like it should bolt onto something. It is very similar in appearance to the one attached to the side of the transmission cooler on a V8 (ESR4329). Looking at that picture it appears there is something with red wires to it on the outer edge of the cooler and the picture here https://www.famousfour.co.uk/new_parts/partslist?veh=rr_p38a&sec=elec&sub_sec=transsense shows the sensor to have red wires to it.

RAVE doesn't seem to show the location of the switch but it does show the location of the connector to it (C1505) as in the LH front corner of the engine bay but as it looks to have a long wire to it, that doesn't really tell you anything.

The fan had stopped working on mine…
I change the cheaper of the two switches, and now it runs constantly…
I was going to change the more expensive switch but it was £150ish so parked that idea for the time being.
If I can find the part no, I’ll post.
My thoughts were that running all the time in Summer is not the worst thing in the world.

https://www.island-4x4.co.uk/auto-gearbox-cooler-temp-switch-esr4330-p-1380.html

That’s the one I changed..

https://www.famousfour.co.uk/new_parts/ff_part?part=31126

This is the one I haven’t changed, and am assuming it will stop the fan running all the time.

Richard, I can only say -- whoooops !!!! I was looking at those cylindrical canisters from under the car, and trying to see between the bumper and the radiator so I thought that, because of where those pipes go, the canisters were a switch of some kind.

My mistake does explain why I couldn't figure out how to attach the sensor. And the red one is the right one for the later car cooler fan - £92.00 !!

As Jim AHH says it may be the most economical solution to just let the fan keep running. My only concern is whether running permanently will shorten its' life expectancy before it packs up. As Jim says, running during the summer can't really do any harm, I suppose.

Anyway, very many thanks for correcting my basic mistake. I will now make sure that I am looking at the front of the car and not the back !!!!

Pierre3.

Unless you do a lot of towing heavy things up hills in very hot weather, chances are the fan would never come on anyway so even if the fan did wear out through constant use, it probably wouldn't be any great loss. The transmission cooler on a V8 is where your intercooler is and that doesn't have a fan.....

I had the over heater warming twice, when the fan wasn’t working.
Once, when I was doing an off road Land Rover experience and the second time was trying to park in Lyme Regis.
No towing, but it was warm with pretty steep slow driving.

Good advice all round. I suppose that one could look at other automatics, and how many of them have a gearbox oil cooler fitted. I don't think that it would be many. I have had a whole selection of things like Jag XJ's, Mercs, and other Japanese 4x4's and I never came across a gearbox overheating problem, no matter how hot the weather.

That's not to say that any of the above don't have a gearbox cooler, but I never came across it before.

Maybe I will just leave it for the time being as I don't tow anything.

Pierre3.

The V8 oil cooler will get a draw from the main engine fan, so essentially its always got airflow.

Most modern autos have a coolant loop in the main engine radiator. I'd say its rare to find an auto without a cooler!

Leaving it running really depends on wether the system has a sensible thermostat, if you over cool the oil the transmission wont like it. I know mine doesnt lock the converter when cold for instance. I'm usually a few miles up the dual carriageway before the gearbox oil finally reaches whatever temperature it wants, and you hear the RPM's drop as the converter locks up.

Perhaps you can find a good used switch instead of spending £100+ on a new one?

Aragorn wrote:

Perhaps you can find a good used switch instead of spending £100+ on a new one?

I suspect you'd be able to pick up a used cooler complete with switch for a lot less than a new switch.

On a slight tangent but still in the same area, has anyone else noticed a change in exhaust note when the transmission gets up to temperature and the Torque Converter locks up? I live just over half a mile from the A1(M) so no matter where I am going, it always involves going on the motorway. Drive along at constant throttle at around 60mph and after about 3 miles, the revs drop by about 250rpm and the car starts to accelerate? I never used to notice it but since I fitted the Gravity stainless exhaust, I can hear a change in exhaust note as if I have given it more throttle. Has anyone else noticed the same?

Richard, I could get a used cooler, possibly with the switches still attached, but a couple of issues occur. One is that I have recently fitted a new cooler radiator and oil pipes due to a leak in the original radiator. I got a very good offer from Maltings for the whole kit so I don't want to change it back out for a used item. But it is a good suggestion which, in other circumstances, I would have gone for.

Secondly, the cost of having a used unit sent from the UK would be almost as much as buying a new switch on its' own. By the time I pay for the radiator [ £30/£40 ?] and then pay the courier, plus the usual nonsense of VAT and duties, I think that I would be up at close on £80/£90. I may as well pay another £10 and buy a new one .

Aragorn, I didn't realise that auto's have a gearbox oil cooler built into the radiator. To be honest, it is not something that I have ever had an issue with before, but that doesn't mean to say that there wouldn't be a cooler fitted somewhere.

Pierre3.

On a V8 it isn't built into the radiator, it's in front of it. There's the radiator and in front of that is the AC condenser with the engine and gearbox oil coolers sandwiched in between. On the diesel the engine oil cooler is in the same place but you have the intercooler between the radiator and AC condenser so there isn't room for the gearbox oil cooler too, hence it being tucked away where the V8 has a front foglight.

I think the L322 has either the oil or transmission cooler built into the radiator though.