Hi, our 03 4.4 v8 with lpg conversion runs great but has on a couple of occasions flashed up the transmission overheating warning. We have been doing some long driving and up and down very steep hills in the lake district.
I know the previous owner fitted a new radiator so I suspect this might be a long standing issue.
What do you think would be the best way of resolving the problem? Am thinking of getting the coolant system flushed, new thermostat and new wiring harness to replace the transmission temperature sensor. If you switch the car off and back on again it clears the fault, this would lead me to believe it is an electrical issue rather but flushing the coolant would be good for the car anyway. It only ever flashes up the warning when it's been run on lpg, might be a coincidence but I think lpg burns or runs hotter than petrol?

The car is great, has 85000 miles on it, new transmission fitted although I don't know when. Has some of thr usual l322 problems such as poor quality trim but I can fix that. Brakes make a bit of a scream at low speed and the suspension squeaks a bit too.

Trans overheat is a state the box goes into if it overheats, it changes the gear change points to increase the revs of the engine and circulate the coolant faster, it will reset on switch off...

It is usually associated with blockage in the bottom of the main coolant rad, you cannot flush this part out because of the design of the rad, the only answer is replacement, it can also be a blockage in the coolant passages in the transmission oil cooler which is on the bottom drivers side of the main rad, this has it's own manifold and thermostat, this stat can fail as well, also the oil cooler pipes from the cooler to the box are known to collapse after time and block the flow of oil....

The main car thermostat will have little to do with your problem...

You need to find out if the temp in the gearbox is getting high or it is a wiring fault, little point just changing things because all that above and a new gearbox loom will cost a lot of money, you need a diagnostic tool to read the live values and find out where the problem is...

LPG and petrol both burn around 1000deg C, LPG burns at less than 10deg higher than petrol, pretty irrelevant really but the old wives tails still circulate....

If your LPG system is set up incorrectly then it can lead to overheating though....

 Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Hi thanks for your reply. The lpg system does require a service. I think my best option is for a specialist to take a look at the vehicle and diagnose the problem. Can anybody recommend anyone in the matlock derbyshire area?

Cheers
james

These cars are very easy to work on, if you have done your own repairs before don't be put off by them, the only extra tool you need is a decent diagnostic tool, the IID tool is good and you could easily diagnose the problem yourself (even if you didn't want to fix it) they are not cheap but you will always get most of your money back as they sell well...  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

If the previous owner fitted a new radiator then it is almost certainly the oil cooler[heat exchanger]If you feel the oil pipes to the cooler you should feel a noticeable difference in temperature.Fit new cooler and check the radiator flow with a hose,it should flow freely at full bore and check the date on the radiator if he has supposedly changed it.Change the transmission oil at least twice and the filter in the sump,clean sump.If possible get a live data temperature readout and check against sump temperature[will not be the same but will give you a guide]Iforget the actual temp figures but I think the sensor trips at 140 deg,it should not get anywhere near that but after I had done all the above to mine [and my cooler was almost blocked] the sensor was jumping all over giving high spikes instead of a constant readout,the transmission sensor was faulty and has been ok since I changed that also .

Hi thanks for the replies. Does the oil cooler/heat exchanger have coolant in it then rather than oil?

The oil cooler is a water to oil cooler, it uses water from the bottom of the rad to cool the oil, it also works as an oil warmer to warm up the box in cold weather, it is attached to a plastic manifold that contains it's own thermostat.

Don't just start changing things, even the oil without finding out where you problem lies, I've listed all the usual reasons, you just need some diagnostics to find out what route to go down.....  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Had the diagnostic check today. Reading came back as gearbox oil sensor fault. Technician said it is inside the gearbox so I would need a gearbox specialist as it's inside the box. Does that sound right?

It's part of the wiring loom, so you will have to have the whole gearbox loom replaced, this is not a big job though, drain oil, sump off, unplug old loom, plug in new, sump on and refill....

Don't think it's too expensive either...

Most decent independents could do it very easily, if your guy can't, then I think it's time to find someone that knows a bit more about FF's to work on it...  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Thanks for the feedback. This was a land rover specialist in chesterfield that told me that. I will talk to where I usually take my cars and see if they will sort it. It does sound like a simple task n it can't harm to change the oil, do they have a filter aswell?

Can anybody recommend where is best for parts? And is genuine original land rover parts best to use? I am going to have the filter replaced too plus o-ring and gasket.
cheers

Wouldn't go genuine LR as you will pay for the box

Go genuine ZF and it will be cheaper, yes there is a filter to change and get a new gasket..

http://www.jpat.co.uk/

Loom

 Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Yes this is the wiring harness I changed on mine,also got it from jpat,£100 delivered,there is a video on youtube on how to do it ,just a bit easier after seeing someone else have a go.The temperature sensor is buried in the centre of the loom,you can find it if you poke around.Typical as the torx for the speed sensor at the front was almost slack yet the rear one that is quite awkward to get to was as tight as f$%k,almost thought it was not going to come out !

Hi. Thanks for your post. I now have the wiring loom and new filter from jpat, took ages to arrive as zf are moving factories.
Is this an easy job to do? Any special tools needed? I can't find anybody who wants to do the job and the specialists have said they have never heard of the teratogenic sensor needing replacing.
Cheers
James

It really is easy to do but a lot of garages are scared of the inside of an auto box... Put another post on asking if anyone can recommend a garage or gearbox specialist near you that can do it... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-