Thread: Auto Transmission Cooler

personally I would go for a P38 oil cooler it's much larger and much more efficient. The hoses do need to be modified a bit apparently, but you will have peace of mind.

this is the next modification I am doing to mine.

blythe

As mentioned the P38 cooler is the way to go and I have just fitted one to my Disco after killing the transmission with excessive heat while towing a 900kg CT. It seems the ZF 4HP-22 runs full pressure (200psi) through the cooler when in lock-up so many after market coolers are not up to the task. I got my P38 cooler new on UK eBAY for around 30 pounds so you can get them cheap if you look around, cost me 29 pounds to ship to Oz using a company called transglobal who you can organise to collect from the seller (much cheaper than DHL etc even though thats who they use to ship). P38 coolers are around 3 times the size of the stock cooler and fit well in front of the rad and easy enough to fit once you get the hose's made up by a hydraulic hose places such as enzed. There is lots of info on aulro if you search on P38 Cooler, I can give you more details as well if you need them. Very good idea to fit one though especailly if your towing up the cape.
Cheers
Mark

Thank you Blythe and Mark, looks like I have some homework to do. Last thing I want is to be stuck in the middle of nowhere with wheels that wont turn. Cheers, Rick.

Look, I went to the Cape last year with my RRC towing a 600Kg camper and did the Northern OTL track.
The Cape road is a variable major dirt road with some areas of extreme corrugation but many areas of excellent road. The OTL is just an average dirt track interspered with creek crossings of short duration , and NO sand.

To suggest that you NEED extra transmission cooling is IMHO incorrect. My trans has done 210KK now. I use Transmax Z and change before a major trip along with the filter. The trans overtemp warning has never triggered on my car except when full of water resulting in a new sensor.

The hardest job for a auto trans is dry sand driving , and I have done some Stockton driving towing my camper as well as Cooloola. I use low range on the beach to keep the revs up and reduce TC slipping.

If a trans failed on a long trip IMHO it is because the transmission was on the way out before the car started the trip. A full service by yourself or a trans shop and flush and refill with a top quality ATF is IMHO all that is required unless you have neglected your trans for many years and only now are thinking about it, and tyhen IMHO a bigger cooler is not going to help much. The trans shop will tell you ( I hope) if the sump is full of clutch material .
Regards Philip A

I read in a Lanrover brochure somewhere that the Rangerover/Discovery auto was engineered to run in low range all day in sand on a hot Afrian summers day. Sounds good enough to me.

same can be said for the fuel tank, tyres, axles or any modification, stock standard is fine because that is what they designed and who are we to presume to know better.

I have a 118Lt tank for extra range, diff locks because they are a traction aid that have been used many many times, a winch bull bar to aid recovery which has also been used many times, upgraded suspension, upgraded brakes the list goes on and I still haven't finished with the mods yet.

Bottom line is many of the places I have been, no standard 4wd would get there of any brand including any stock landrover as well. A larger oil cooler is just the same it is an added insurance to ensure that on a 45+ degree day in the shade (therefore potentially 60c + including reflected heat) and I am in soft sand I wont fry the gearbox and have to fork out over $3k to get it fixed. If the original DI oil cooler is so good why did they put a bigger more efficient one in the newer models?

Nothing wrong with standard but some of us do go way beyond what the standard vehicles design parameters are, therefore require modifications to ensure we safely get home again.

Originally Posted by blackbuttdisco

I read in a Lanrover brochure somewhere that the Rangerover/Discovery auto was engineered to run in low range all day in sand on a hot Afrian summers day. Sounds good enough to me.

And you believed them, LOL, Regards Frank.

Originally Posted by blackbuttdisco

I read in a Lanrover brochure somewhere that the Rangerover/Discovery auto was engineered to run in low range all day in sand on a hot Afrian summers day. Sounds good enough to me.

The ZF 4HP22 was used in BMW, Volvo and Peugeot saloon cars well before land rover used it in the Discovery, therefore it was not purposely designed for the Disco or even a 4WD. The ZF 4HP24 is a stronger box and some of the clutches etc can be used in the ZF 4HP22 as Ashcrofts UK recommend. The ZF specialist that repaired mine said they are not really built for heavy towing applications and he was reluctent to give me any warranty if I continued to tow after the repair.
ZF themselves also state that they have no problems with this gearbox that can't be attributed to excess heat. Mine had had regular fluid and filter changes but still died prematurely at 120k due to overheating.