I added engine and trans oil temp gauges to my dash but have not added the sensors. i was also looking at utilizing the oil sample ports as the trans port is on the cooler supply line so overall trans output oil temp.
the engine sample port appears to be post cooler but it is convenient
As for the transfer case, there is an access cover in the middle on the rear face to get at the output speed sensor. Pull it and take a look there. If memory serves there is nothing immediately behind that cover and it could probably be drilled and tapped for a temp sensor. Now where the running oil level in the transfer case actually rides in the sump, I have no idea as I do not know where the scavenger pump internal gallery is actually routed from the port where the screen and hose are located... Since it is capable of picking up to P6 thrust bearing parts it may pull oil from quite low. All those parts, after they thrashed the P6 clutch and housing components, exited the P6 housing thru its drain hole right down near the bottom of the P6 case gasket… from there some found their way to scavenger suction, and some usually find their way down to the transfer drain plug
since you are about to have a core to disassemble, you could answer these questions?
read back thru the threads on these failures and analyzing the pics and diagrams a little more, these failures are either happening when the P6 is released or when thru vibration/acceleration bring the center carrier(~7#?, plus the clutch component weight) back against the thrust bearing. The piston is all the way in the back and has a hole in the middle for the center tower of the housing. It is held in battery by a spring pack secured to the center tower with a large snap-ring. When pressure is applied it pushes forward compressing the springs and the fixed and rotating discs to lockup the center carrier and center shaft. This will push the carrier away from the thrust bearing. When P6 is released the center springs retract the piston leaving the carrier and discs to slide to the rear and contact the thrust bearing. Since the transfer case main gears are helical, there may be some other dynamic involved here like shifting between forward and reverse that causes P6 plate carrier movement to the rear, as the nose/snout of the carrier protrudes forward into the output shaft rear carrier bearing in the back of the transfer case under a cover
The pressure lube to the P6 enters the center rear of the housing from the left side of the transmission(piston pressure is applied from the bottom gallery). lube flows past the center shaft bushing in the center housing tower, then passes thru the space between the stationary center tower and rotating plate carrier. That is where the thrust bearing is located. Oil then flows thru small holes in the carrier and out amongst the rotating and stationary clutch discs or out the back of the cupped center carrier and down past the piston face to the bottom of the case. The thrust bearing appears to be well lubricated…
The root cause of course is that Allison put a 1/8” thrust bearing into a 3/8” cavity next to a heavy component that was allowed to move freely…
working on lifting my hab floor today to pull my P6 assembly and put a bushing in where the roller thrust is…
