I just added a transmission cooler and remote transmission fluid filter to my '89 Lincoln Town Car, and I thought it couldn't hurt to add one to my Jag (2008 44k miles).

Has any one done this? Any advice would be welcomed. Should I change the transmission oil at the same time, if I do this?

I've only had the jag a couple of months and the only work I've done on her is new oxygen sensors and a coolant flush.

Thank you!

 

The X350/358 already has a transmission cooler, it's part of the radiator assembly. It also has filter in the transmission, it's an integral part of the plastic sump which is discarded and replaced with a new one when the transmission fluid is changed.

Current advice from ZF, the transmission manufacturer, is that the fluid should be changed at between 50,000 and 75,000 miles.

 

The Lincoln has a cooler in the radiator also, I added the extra cooler for additional fluid cooling and everything I've read on the remote transmission oil filter, says change it every time you change the motor oil.

I want to keep my jag a long time and thought this extra transmission cooling would be a good thing.

 

I've never read anything about anyone fitting an extra cooler. The transmission control system monitors fluid temperature and it has a '*hot mode' to decrease the heat loading on the transmission if it gets too hot (for example if you're towing).

As to adding an extra cooler I could imagine that overcooling the fluid could be as deleterious to transmission wear as overheating.

Frankly the best way to get the best life out of the transmission is to make sure you change the fluid every 50,000 miles.

And anyway, where would you put a cooler ? There's very little spare space under the hood !

*"Hot Mode
"This is one of the adaptive modes the transmission can enter when conditions are correct. When the
transmission fluid temperature, chip temp, engine oil temp or coolant temperature becomes hot
enough to reach threshold values, the TCM will cause the transmission to enter Hot mode. This mode
will automatically engage new shift and lock-up maps to reduce heat generated within the
transmission. The shift map will enable the transmission to change to higher gears at lower vehicle
speeds and the lock-up map will engage the lock-up clutch at lower vehicle speeds and in lower
gears. The effect of this is that less heat will be generated within the transmission due to the effects
of lock-up clutch slip and churning effects. There will be forced upshift strategy used in hot mode. To
exit hot mode the selector lever must be moved or the brake pedal applied or the accelerator pedal
applied 100%, during all of these methods of exiting from hot mode the fluid temperature must be
lower than the threshold values." (W/shop Manual)

 

Fitting a secondary cooler could depend on how and what you do with the vehicle. In Ford's version of the 6HP26, (not your 89) they use a valve inside the case to control cooler operation, where the fluid has to reach a predetermined value before it passes it to the cooler. Jaguar does not use this, and the TCM in Jaguar vehicles have different shift patterns that change lockup in the torque converter to help transmission temp rise above 50C. At 50C, the shift patterns and TC operation change to fully warm operation. Adding additional coolers could change the dynamics of shift patterns, and for the worse... i.e. less gas mileage, no longer adapting much like when a thermostat stuck open always keep the ECM from ever going into closed loop. Since I've never tried it, I can only convey some possible issues that could crop up by cooling the fluid below what the system was designed for. Pat the Cat has already given you some examples of how sensitive it can be to temps.

 

Thank you for the advice. I didn't realize how "smart" Jaguars are. I'll leave the transmission oil coolers to the Lincolns I have, my '89 just hit 100k miles and my '98 has 163k miles.

 

Oh ! ... I think that goes for quite a lot of us when we first got one. The electronics in them is ... quite complicated (British understatement)