Thanks Gerry, I was hoping you'd say that.
1994 E320 Wagon
722.369 transmission
240,000 miles
original transmission
failed reverse
forward gears normal with perfect shifts
no transmission leaks
fluid changed every 30K miles since new
In the process of a partial rebuild, here's where I am so far:
Removal of rear cover revealed very worn B3 friction discs. I've included a picture of the B3 piston, note the scoring caused by interference with the K1 clutch. The B3 friction bands are paper thin, this is obviously what allowed the B3 piston enough travel to cause the impact with the K1 clutch. I understand this is a very common failure, which leads me to my first question:
Does this kind of damage require a full rebuild to insure no metal in the system? My guess is maybe, but I'd like to hear from the experts. Some additional info, last time I changed the fluid and filter, I noticed some gray streaks when cleaning the pan. So far, disassembly has not revealed any additional evidence of ground up aluminum.
Disassembly of the B3 piston revealed a torn inner lip seal, also a very common failure from what I’ve read. Picture is included with this post. I’m beginning to think that my reverse failure was the result of this lip seal failing, not worn friction discs. I would think that worn discs would result in reverse slowly getting weaker and weaker over several months. With a failed seal it seems logical to expect a more immediate failure. My symptoms were a slow advance of weak reverse, and then immediate failure.
After lots of reading and thinking, I’m unsure just how much rebuilding to do. At a minimum, I’m planning to overhaul the B1, B2, and B3 pistons with new seals, and of course replace the B3 friction discs. I’ll also replace the front side shaft seals.
My dilemma is whether or not to open up the small end (output shaft) of the transmission. Doing so would allow shaft seal replacement and a check/rebuild of the K2 assembly. I’m less concerned about the shaft seals—If I don’t replace them and they start leaking, they can be replaced without removing the transmission.
I’ve checked the free play of the K1 assembly with a feeler gauge as per the FSM, picture included. My value is 1.34 mm, max acceptable value after rebuild is 1.30 mm.
Can I conclude from this measurement that the K1 clutch assembly (and hopefully the K2 clutch assembly) is (are) serviceable?
Anybody have a feel for the likely condition of the K2 assembly?
Thanks for reading.
J. M. van Swaay
