XJ Transmission Oil Coolers

[Rodgebone]

Carves, there a test port for checking line pressure (towards the back on the driver side from memory). readings arent taken from the cooler lines and like kyphonii stated, 263 psi would have blown the cooler lines off at the connections

[kyphonii]

I've spent countless hours reading post on XJ cooling from around the world.
A lot of info regarding the flow thought the aux cooler. A lot of people advocate the opposite of what I think.
I'm of the view that the hot auto oil goes to the aux cooler first so as to take advantage of the significant difference in oil temp to air temp. the greater the difference the greater the cooling , then on to the radiator heat exchanger entering the rad from the bottom and exiting from the top so as to eliminate air locks and to cool the rad if the oil has been cooled to below 100'C which is should have, this would also stabilise the auto oil on startup. the rad will try to take the oil up to around 100'C but I think the oil doesn't stay in the rad long enough to increase the temp much , based on how long the transmission takes to warm with the rad at 100'C.
If my theory is right , the hotter the oil gets the greater the cooling effect of the Aux.

[kyphonii]

The manual that hides the transaxle from me tells me that the RH-30 auto transmission has 5-30 lbs on the cooling lubrication circuit. I would assume the AW-4 would be similar.

[carvesdodo]

Originally Posted by Rodgebone

Carves, there a test port for checking line pressure (towards the back on the driver side from memory). readings arent taken from the cooler lines and like kyphonii stated, 263 psi would have blown the cooler lines off at the connections

Ahhhhhhh .... more FSM vagueness then - confusing things that should be simple

Would be a bit much expecting the leaky clip arrangements to last for long at WOT pressures.

BTW kyphonii ...... Im thinking "transaxle" is probably just a poor choice of terminology for the gearbox .... a result of the Renault affiliation with AMC when the XJs were conceived ....

[kyphonii]

Originally Posted by carvesdodo

Ahhhhhhh .... more FSM vagueness then - confusing things that should be simple

Would be a bit much expecting the leaky clip arrangements to last for long at WOT pressures.

BTW kyphonii ...... Im thinking "transaxle" is probably just a poor choice of terminology for the gearbox .... a result of the Renault affiliation with AMC when the XJs were conceived ....

I think the manual may have include later models.
I'm a poor person and can only afford early model manuals.

[carvesdodo]

Originally Posted by kyphonii

I think the manual may have include later models.
I'm a poor person and can only afford early model manuals.

heh heh .... mines a post update ... and its supposed to have a transaxle as well according to the manual .... guess I can always pretend its a porsche ....

Im pretty sure there wasnt a real lot of effort put into updating manuals ..... as the years went by.

Even my lawnmower manual has a better engine oil viscosity table for different climates than whats in the XJ FSM ..

[Nakkas]

Originally Posted by kyphonii

I've spent countless hours reading post on XJ cooling from around the world.
A lot of info regarding the flow thought the aux cooler. A lot of people advocate the opposite of what I think.
I'm of the view that the hot auto oil goes to the aux cooler first so as to take advantage of the significant difference in oil temp to air temp. the greater the difference the greater the cooling , then on to the radiator heat exchanger entering the rad from the bottom and exiting from the top so as to eliminate air locks and to cool the rad if the oil has been cooled to below 100'C which is should have, this would also stabilise the auto oil on startup. the rad will try to take the oil up to around 100'C but I think the oil doesn't stay in the rad long enough to increase the temp much , based on how long the transmission takes to warm with the rad at 100'C.
If my theory is right , the hotter the oil gets the greater the cooling effect of the Aux.

In the US Jeeps, the transmission cooler is on the left side of the radiator and I would assume that the left tank would/should be cooler than the engine temp (100 deg)