Transfer Tube leak

Nice post @Flechtight ! Re: No oil will pour out, it’s most likely a case drain tube, this tube obviously does not see high pressures but leaks like heck when damaged.

You're correct. This tube is either the equalizing vent or drain between the trans & axle sections of the ZF 948 transmission. (it's been a while, I can't recall the exact function). It is above the full trans fluid level however so it will not be normally below the oil line.

Something interesting. while there are differences between the ZF 948 made by ZF and Chrysler, most of the internal gearing is the same with the exception of one of the snap rings and valve body. The outer casing, trans cooler and other external components are also different. Also, most importantly, each manufacturer does their own TCU programming. This is why, say, our Cherokees have wonky shifting but, say, Hondas, Range Rovers etc. which use the same transmission, have never had shifting problems. It's just the case of one having better programming (unfortunately, we came up on the short end of that stick).

Something to note also, on the driver's side of our transmissions to the right of the half-shaft opening, there's a check/fill port. On Hondas, this is the actual port used to check if the trans fluid is at the correct level. They don't use the Jeep "dipstick in the fill port" method. They can also add/remove oil here much like we do on our PTU or RDM fill ports. To check if one has the correct trans fluid level, you warm the trans to 120deg F and then unscrew this check port. It should be filled to the bottom of the fill plug level.

Photos below... One is from my Cherokee, the others from Honda.

Flechtight said:

i just got my Mopar dipstick, I’ve seen some videos and some mention engine running while checking oil levels others do not mention this.
How have you been doing this?
I plan on changing after the holidays, all fluids,
Do you find it easier to lay on the engine to reach behind for the fill/dip stick plug or through the left wheel well?

Click to expand...

1. It's supposed to be running. I go in from the wheel well method (take off driver's wheel). The thing [to me] however is once I get the tranny temp up to min 122degF, who wants to stick their hand in there (tight quarters) and take a chance burning themselves? And this is regardless whether you go in through the driver's wheel well or on top of the engine. Either have plenty of potential hot spots.

2. To me, you have to have super-long arms to do the top-down method. I know some guys have said they've done it but you need to practically lay down on the engine to do it and even then it's a tight and long reach down. Perhaps if you use a 3/8 socket driver with long extension and a swivel at the end (though you'd need some way to make sure after taking the fill plug out, it says on the hex socket head and doesn't fall down into the belly pan/skid plate) it could be done. For me, it takes more time than just jacking up and going in through the wheel well which, for me, I can do pretty quickly now (I've done it twice - first time took an hour being careful, not knowing the process 'by feel' etc. Second time I was done in 20 minutes.

3. If you don't do it running it seems to give the wrong reading. For example, the first time I went to do it on my 2014 TH, I left both the ZF Fluid bottle and car overnight outside so they were both at the same temp. First thing I did after removing the tire/fill plug was to get a measurement. It came back at 50mm! I knew that couldn't be correct (that's above the hottest part of the scale) so I did it again 3 times in total, each was the same. And I had made sure the car was level so that wouldn't be affecting the measurement. So, it appears that if you DON'T have the engine (and torque converter) running/spinning, the measurement will be off. It was at that point that I decided I would go with the drain and re-fill with like volume since I couldn't trust the level due to it being cold and engine off. I have no leaks from my tranny so since they're sealed units, unless you have a physical leak, your level should be correct so the drain-measure volume-fill with like amount should work fine.