Quote:
Originally Posted by Deezelweazel
Ok, and you do know that tranny fluid also needs to have an operating temperature to avoid unnessecary wear?
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ummm yep ... and even tho I read all chrysler FSM temperature info with
just a hint of sceptism ...
The FSM states 50'c - 80'c for the AW4 ...
Now since the AW4 in the XJ is known to run "
hot" compared to other autos and even the AW4 in other brand vehicles ... I'm quite prepared to accept the "low" factory specs & lower ... as a nescessity, for a sump temp ... when reading similiar info to this -->
http://www.digi-panel.com/trannyoil.htm
Of course there is no indication in the FSM whether that is a sump temp, or an after torque converter temp ... or an internal operating temp ....... but its probably safe to presume its the sump temp ... given expected higher temps of the other two.
Quote:
Originally Posted by Deezelweazel
The inline tranny cooler is very effective. And according to bernoullis first heat law most people obviously do not understand how it works.
Heat is aleays transfered from hot to cold never vice versa.
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Effective - when the heat exchanger is in the correct side of the radiator and has cooled radiator liquid, to transfer heat to ... and the engine cooling system is adequate enough in all driving conditions, to
not be affected by the heat transfer.
The fitment of the little aux cooler, to RHD export 4.0l models - with the heat exchanger in the radiator hot side ... is obviously an attempt to provide the same cooling result, as LHD, snowbound XJs, radiator cold side, in-tank heat exchangers - which dont have an aux cooler fitted as standard.
According to chrysler specs ... the aux cooler is required for heavy duty use of the gearbox ... therefore IMHO .... the factory aux cooler, is a nescessity for Aust. versions - but is not a generous gift from chrysler coz they thought we all towed stuff ...
It needs to be upgraded for heavy duty use ... and perhaps even just to make up for our higher average, ambient temps - which dont have as big a windchill factor on radiators/coolers, as what northern hemisphere average, ambient temps do.
Quote:
Originally Posted by Deezelweazel
That means tranny fluid will never get heated up by coolant except during warm-up which is intended in this way to gurantee a quick operating temperature of the fluid.
Temps lower than 80°C cause increased wear inside the tranny.
so an aux cooler has to be adjusted to the performance line.
Bigger is not always better.
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Again ... the heat exchanger needs to located correctly for the intended process to function correctly.
Agree with adjusting the cooler to meet operational requirements ... Thats the same as the requirement to tickle the coolant system depending on operation of the vehicle ... and its operating area.
Mind you ... Its that fixation wth a single "
best" temp - that is the downfall of the 4.0l cooling system.
Its rather amazing that a vehicle manufacturer thinks that it can pluck a single temp out of ... of ... of .... somewhere .... and make it a target/goal temp .... When all the components / factors that facilitate that temp are variable ...e.g.
Ambient temp windchill factors,
Ambient reflected ground temps,
Coolant mix pecentages,
Radiator core qty & construction,
Driving styles and vehicle use,
Engine loads,
Performance of aged components,
Performance of different brand new components,
Faulty new components,
Maintenance schedules
Fuel type availability.
Much better IMHO to have a system that fluctuates within
acceptable limits under the various loads - rather than an expensive, high maintenance system where 100% efficiency of all the variable components/factors is required.
Perhaps tho ... chrysler actually expected everybody who bought an XJ, to only buy genuine parts and liquids whilst having scheduled dealership services done ....
Hopefully everyones input and feedback, in this thread will provide a "most suitable" oil cooler setup for our conditions, at some point in the future.
For those of us working the gearbox hard in the warmer areas of Oz .... and until a
known standard is worked out .... I think that initially, bigger is better ..... as a bypass line in parallel with the cooler, is easy done to combat overcooling, if needed ...
As far as a large oil cooler obstructing the radiator airflow goes ... yes, it will ... but I've had enough junk in front of my radiators to show its not that big an issue ... even with factory radiators.
Perhaps tho ........ it is a more critical issue with the TD2.5l.
Fabio has the right approach ..... compromises in some areas need to be accepted - to achieve a balanced,
overall improvement.