XJ Transmission Oil Coolers

[ChrisXJ]

Thanks for the info Rainman. I did read the Go-Jeep write up and it did make alot of sense. I do still have the viscous fan on mine and was wondering can I still run the cooler in the same position as Go-Jeep and acheive the same outcome. Secondly did you manage to purchase the Cooler from an Australian Supplier. Cheers

[rainman]

I got mine from summit racing in the states.

I like the idea of a cooler that is not quite as long as the one gojeep used, in the same place and with a fan in front of it.

Although I have not tried it.

[tazwegion]

Originally Posted by ChrisXJ

I am going to install the Craig Davis P/N 678 cooler and a VDO gauge to the XJ AW4 Trans. I have done the search and I am now totally confused with all the opinions on how to install the cooler. Can someone please give me the best way to install the cooler. Some threads say run the Radiator trans cooler first and some say run only the new cooler. Others even say run the OEM cooler and the new Cooler. PLEASE HELP

I installed the Davies Craig #678 cooler in this configuration because...

• The plumbing was easier
• I wanted faster warm up times for the transmission oil (reduce cold operation wear)
• The oil cooler assists the radiator via the transmission heat exchanger located in the radiator "hot" tank
• The coolest possible oil was in the return line to the transmission

More details can be found in the thread titled Oil Coolers ... XJ nescessities ???

[ChrisXJ]

Hey Taz. Thanks for the very benificial info and feedback from your own system.I will set mine up as per your specs. Can you confirm if you still run the Viscous fan in the xj.

[rainman]

Originally Posted by tazwegion

I installed the Davies Craig #678 cooler in this configuration because...

• The plumbing was easier
• I wanted faster warm up times for the transmission oil (reduce cold operation wear)
• The oil cooler assists the radiator via the transmission heat exchanger located in the radiator "hot" tank
• The coolest possible oil was in the return line to the transmission

More details can be found in the thread titled Oil Coolers ... XJ nescessities ???

with this set up what sort of daily/average operating temp do you get in the sump?
I have mine the other way and it sits mostly 70 -80, occasionally will hit 90

[tazwegion]

Originally Posted by ChrisXJ

Can you confirm if you still run the Viscous fan in the xj.

No actually the previous owner fitted a thermofan (bloody noisy) unsure of the CFM figure but I'd be tempted to "retro fit" a clutch fan should I come across one at the wreckers (I have no fan shroud fitted either)

Originally Posted by rainman

with this set up what sort of daily/average operating temp do you get in the sump?
I have mine the other way and it sits mostly 70 -80, occasionally will hit 90

I have no temperature monitoring device for the transmission, however I can tell you the "shift" lever shaft that on occasions became too hot to touch now only gets very warm, I do plan on fitting a temp sensor in the future and am leaning towards the unit trialled by carvesdodo in the thread previously linked (OR a basic VDO configuration)

[TERRA Operative]

My preference is to get rid of the radiator oil cooler all together to reduce the total heat load on the engine cooling system.
When off load, the oil passing through the radiator can also reduce the avaliable thermal capacity of the oil cooler for the transmission, as you are effectively using it as a heat exchanger for the engine cooling system. (Which should be up to scratch to not need the oil cooler to help it cool down).

The number one killer of transmissions is heat, my philosohy is to keep them as cool as possible, especially on slow moving vehicles. They need all the help they can get with their inherant lack of free airflow.

In the cars I have built, we have found that it is beneficial to have the transmission cooling system seperate to the engine cooling system for this reason. The Trans-Am Firebird we built benefited greatly with two big trans coolers in place of the radiator oil cooler, we not only saw much cooler trans temps (the box was built to handle up to 700Hp) but also saw cooler temps from the worked 351 Chev we squeezed into the engine bay.

In Australia, most of the time the climate will allow the box to heat up quickly enough anyway. On my supercharged Levin import (and the N/A race car), the manual gearbox doesn't have a thermostat on the oil cooler and it has no dramas with spinning the synchros up quick enough when cold.

Just my opinion anyway...