Transmission-Transfer Case Fluid Connection |
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Bob W
Member Sponsor Member x 4 Joined: 08 Aug. 2005 Location: Monticello, NY Status: Offline Points: 1691 |
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I don't have anything else to go with that illustration :( |
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TERRY
Member Sponsor Member Joined: 22 May 2007 Location: BOULDER COLORADO Status: Offline Points: 3400 |
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SEAN, i agree that each case should be checked independently, however the tc will be filled above the fill hole by 1/2 pint if the trans is at full with the "new" method of filling them. My point is, if the trans is full, then removing the tc fill plug would have GL4 spilling out but no way of knowing if the tc is full. And I can see that if there is a leak the trans would be full do the pumping action of the gears and the tc could be low or almost empty. So, should we just check to see that the trans is full, then try to slowly add more GL4 until it won't take any more?
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BOULDER 48 2A
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samcj2a
Member Sponsor Member x 5 Joined: 21 Oct. 2006 Location: Arlington, VA Status: Offline Points: 8549 |
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Terry,
Don't you have it backwards? I thought that the Transfer case held 3-1/2 pints while the transmission held 3 pints. Am I missing something here?
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sean
Moderator Group Sponsor Member Joined: 20 July 2005 Location: North Idaho Status: Offline Points: 7388 |
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Terry:
No it won't. The drain-back hole is at the SAME level as the transmission fill hole. So no oil can flow into the transfer case until AFTER the transmission is full. If you stop filling the transmission as soon as it hit's the fill hole level, the TC would not get any "extra" oil. Perhaps a small dribble would get through, but nothing of consequence.
Exactly. In theory (if the "pumping" action works as expected), the transmission would always be replenished to its normal fill level with transfer case oil, leaving the TC low. Sean Edited by sean - 30 June 2011 at 2:38pm |
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SYLVANWILLYS
Member Joined: 27 May 2011 Location: Ewing, NJ Status: Offline Points: 284 |
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----Well it sounds like a significant missing piece of the always fun Willys
Puzzle has been found and placed. Special thanks to Sean for his normal detailed analysis and discovery and also to BobW for filling in with that very key piece of info.
----SO I GUESS THE TWO REMAINING THINGS IN MY MIND: 1) Just so I and others understand the proper filling sequence and fluid-flow dynamics going forward, Sean please confirm or correct my understanding: On as level ground as possible drain and fill the TR and TC to their respective fill hole levels. While driving the TC fluid will "pump" into the TR. As long as the TR is filled to its fill hole level, the pumped TC fluid will "overfill" the TR and the excess will flow back (by gravity) to the TC via a connecting hole. An external TR leak would not initially lower the TR fluid level (because the TC is pumping fluid into the TR) but would cause the TC level to drop (until some point where the TC would no longer be able to pump to the TR). That about it? 2) Empirical Evidence, the ultimate checks (Sean please comment if disagree with these checks or recommend others): To prove all this I guess the things that could be done: ----On level ground have both units filled to their respective fill hole levels. Raise the front of the jeep significantly to duplicate an uphill situation and go inside for a cup of coffee. Then back to the garage and lower the jeep and QUICKLY check the levels in both units. At this point we would expect the TR level to be below its fill hole and for fluid to drain out of the TC fill hole (plug the TC quickly so not much escapes for the next step) ----Now go out and drive for 10 miles or so and come back to level ground and check both units' fill levels. If all is as expected, both units should be fill to their fill hole levels and nothing should drain out of either. Thanks as always for everyone's help and enjoy your July 4ths. Best Greg |
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sean
Moderator Group Sponsor Member Joined: 20 July 2005 Location: North Idaho Status: Offline Points: 7388 |
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Greg:
That's it, as I see the "theory". Unsure of how many "miles" it might require though. It's a "squirt" system, not pressure, so I would expect the rate of circulation depends on road speed. At higher gear speeds, you'd get more forcible "squirt", and the trans would replenish quicker. Also explains why they continued to say to maintain case levels independently. Doesn't matter which one you fill first, as long as they're at their respective fill plug levels, the system will maintain it (barring any leaks). The 3 vs 3.5 pints spec difference was just an "update" to the manual. As you've discovered, it takes more than 3, but less than 3.5, to fill the TC. Sean
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SYLVANWILLYS
Member Joined: 27 May 2011 Location: Ewing, NJ Status: Offline Points: 284 |
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[QUOTE=sean]Greg:
That's it, as I see the "theory". Well since I was going to drain and fill the Transmission and Transfer Cases over the weekend I figured I might as well add a few steps and test the theory. Bottom line I think that Sean's prior research and ultimate conclusions within this post were on the money. First thing I did was drain 3 pints from the Trans and 3 from the TC (TC has a slow leak so did expect less than 3.5 pints from it). I then re-intstalled the Trans' drain plug but not the TC's. I then filled the Trans. It took 3 pints and started flowing out its fill plug hole, and nothing coming out the TC's drain hole. I then triggered in an extra ounce or two into the Trans and it quickly also started running out of the TC's drain hole. So confirmed that Trans-TC connecting passageway is at same height as Trans fill hole. Eventually just a slow drip coming out of Tran's fill and TC's drain holes and I reinstalled both plugs. I then filled the TC and it took 3.5 pints. Then let it sit overnight. Next day I opened Trans fill hole and nothing coming out but was filled right to the lower edge. Then opened TC fill hole and as I expected some started coming out. I had figured that since there was a little still l coming out of the Trans fill hole when I closed it the night before, that it would travel thru the connect passage during the night and raise the TC's fluid level a bit. I let it drain till a slow drip and installed plug. I then jacked up the front axle so that both front tires were around 11 inches off the ground and I left it that way for around an hour. Came back and lowered the jeep back down and checked the Trans fill plug and the level was 7/16" below the bottom of its fill hole. I then opened the TC fill plug a little and it wanted to come gushing out so I screwed the plug back in. I then took it for an 8 mile ride and parked it back on the same marked spots on the garage floor. I opened the Trans fill hole and it started seeping out a bit and I figured the oil was now hotter and probably expanded a little and to keep things more valid I plugged it right back up and let it cool overnight and checked levels today. Sure enough the Trans was filled right to the bottom edge of its fill hole and nothing ran out. Same thing at the TC's fill hole. So as far as proper filling of units that have the connecting passageway, it really is as simple as filling each unit to its fill hole and then checking levels once in awhile. It seems the TC will keep replenishing the Trans's fluid so that the Trans level will stay optimal until there is not enough left in the TC to do that anymore. Possiblly the Willys engineers were prioritizing the health of the Trans over the TC? Trans tougher to access or more expensive to repair perhaps? TC more rugged and can survive low fluid level better? |
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sean
Moderator Group Sponsor Member Joined: 20 July 2005 Location: North Idaho Status: Offline Points: 7388 |
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Great confirmation Greg!
I think it was just a case of solving a problem that had existed since the T-84, and the implementation was just happenstance. They had considered an internal "mechanical" pump system, but apparently this "KISS" system worked good enough that the pump never made it to production. See patent #2608273 (Lubrication System) from the link here: Sean
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willys54wagon
Member Joined: 24 July 2008 Location: Ames, IA Status: Offline Points: 1444 |
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The summary of this is that you should check both but that the TC level will be the most likely to be low.
This reminded me of a musing by Doc Vern on the WT site. He was trying to make filling easier and evaulating easier. I did not see a final application though I might have missed it. The one thought was to take out the breather on the TC and run a hose to the firewall which would serve being a higher level breather as well as an easier way to fill the TC. Remove the fill plug, and then fill from above. Much nicer for us older folk with bifocals and rusty knees. The trans did not have a breather so not as easy to do this. For the trans you could attach a tube to the fill hole but how meaure? maybe a t with a 90 attached or an oil level indicator on the drain hole http://www.mcmaster.com/#liquid-level-sights/=ithvu0 In light of this discussion one could attach the tube to the TC breather for lube addition and maybe put a oil level indicator on the fill port of the TC. Monitor from the TC and check the trans occasionally until you reach a confidence point. Other solutions would be better knees and eyesight, or the tried and true method , when it stops leaking, we are low on fluid.................................................. I do remember some discussion that with on overdrive it might be good to have a higher level of fluid in the TC to make sure there was plenty of lubrication available. This could be done with the above set up. The discussion was that a little overfill of the TC would not be harmful. Thoughts? |
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Two jeeps on the road, one is close and the rest are dreams.
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willys54wagon
Member Joined: 24 July 2008 Location: Ames, IA Status: Offline Points: 1444 |
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Another thought on this would be to buy the vented 90 degree level indicatorhttp://www.mcmaster.com/#liquid-level-sights/=ithvu0, put it in at an angle (for better visiability and practical installation) and take the top off to continue a tube to the firewall for fill and breathing. Cheap paper gas filters have been used at the top for filtration. Would creating a breather for the trans help prevent some of the oil coming out of the top of the trans?
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Two jeeps on the road, one is close and the rest are dreams.
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JeepFever
Member Sponsor Member Joined: 07 Aug. 2012 Location: VA Status: Offline Points: 2747 |
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Great work guys, on the theory and testing.
After reading thru this thread, I think it confirms my method of checking and filling, but I wanted to run this by the group to be sure. I will be adding an O.D. unit soon, and want to be doubly sure that there is proper oil level in the tranny.
I have some homemade skid plates on my CJ2A that make it difficult to access the fill plug on the tranny. I also run without a floor coverplate over the tranny, (no good reason, but it does make it easy to access shifter tower bolts)
For a drain/replace service: - remove both drain plugs (there are holes in skid plate for this). - After oil is drained, replace plugs.
- remove TC fill plug
- pull the shifter assembly off top of tranny. (goes fast with battery impact wrench)
- pour 3 quarts into top of tranny, and let set a little while
- add more slowly until oil starts coming out of TC fill hole, stop pouring
- replace tranny shifter assembly and TC fill plug
To check oil level:
- only necessary to check and add to TC fill.
(as noted in thread: this should be done after level driving, and cooled down)
I think while installing the O.D. I will pull off the skid plate so that I can also check the tranny fill for a while, just as peace of mind. If the tranny is always full, even though the leaks cause TC level to drop, we will have more empirical evidence for this thread, that the "pumping" really works. Edited by JeepFever - 15 Aug. 2012 at 8:57pm |
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