904 transmission leak in my Gremlin

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   Nothing new, right?  Just over a year ago, I had the leaky shifter shaft seal replaced, as well as the speedo cable seal. Everything was nice and dry (no leaks)   until earlier this  week, when I took a long drive (160 miles) on mostly highway. Parked it in the garage, and the next day...big puddle, with a little pool still surrounding the shifter shaft seal.  Can anyone say why the seal would fail so quickly (about 2000 miles since the repair last April)?  I've read much on this forum and others about this somewhat common problem. Any one else experiencing the same?

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blumontag Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Mar/05/2013 Location: minneapolis Status: Offline Points: 837	Post Options Post Reply Quote blumontag Report Post Thanks(0) Quote Reply Topic: 904 transmission leak in my Gremlin Posted: Jun/22/2018 at 9:49am
	Nothing new, right? Just over a year ago, I had the leaky shifter shaft seal replaced, as well as the speedo cable seal. Everything was nice and dry (no leaks) until earlier this week, when I took a long drive (160 miles) on mostly highway. Parked it in the garage, and the next day...big puddle, with a little pool still surrounding the shifter shaft seal. Can anyone say why the seal would fail so quickly (about 2000 miles since the repair last April)? I've read much on this forum and others about this somewhat common problem. Any one else experiencing the same?
	72 Gremlin X

Pdok Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Apr/03/2011 Location: Alabama Status: Offline Points: 1025	Post Options Post Reply Quote Pdok Report Post Thanks(0) Quote Reply Posted: Jun/22/2018 at 10:17am
	Don't know how they fixed the leak the first time, but if it didn't involve this: https://www.sonnax.com/parts/1820-shift-lever-case-bore-repair-sleeve they probably didn't do it right. The condition of your VB in that area may not allow effective repair. 904/727 classic leak scenario. Note, it will be MUCH easier with the trans out, but theoretically can be done in the car. Either way the VB is coming out, so a great time to fix all the other 904 annoyances and get yourself a shift kit installed... plus check bands and all the other stuff that gets exposed. If you pull the trans, check the torque converter carefully for hairline cracks, replace seals, while you've got it out.
	76 Grem X 258/904,4.0 head/MPFI, Comp X250H cam, Hughes springs, Clifford header, serpentine swap.

blumontag Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Mar/05/2013 Location: minneapolis Status: Offline Points: 837	Post Options Post Reply Quote blumontag Report Post Thanks(0) Quote Reply Posted: Jun/22/2018 at 11:46am
	Thanks for the insight. I doubt the Sonnax sleeve was used. The job is way beyond my knowledge/skill set, which is why I took it to a well-respected shop here in Minnesota. Your remark about the condition of the valve body got me curious. I have just recently started hearing a funny knocking noise when braking, which continues for a few seconds when I've stopped. One article I just read says this may indicate a valve body problem.
	72 Gremlin X

Pdok Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Apr/03/2011 Location: Alabama Status: Offline Points: 1025	Post Options Post Reply Quote Pdok Report Post Thanks(1) Quote Reply Posted: Jun/22/2018 at 12:48pm
	Don't misunderstand, I'm no transmission expert, just had this exact leak myself! I chose to put a Cheetah VB in because I wanted a shift kit anyway, and I was not thrilled by how my transmission guy described the expected longevity and difficulty of the other solutions. Finding a VB core is pretty easy for a 904, but getting one that wouldn't be worn in that spot already was hit/miss. So, I went a different route, but it's certainly not for everyone's taste on the upgrade list. I wouldn't go right for a replacement VB, but you need to evaluate the condition of the shaft seal, the hole itself, and the corresponding part of the VB. Slop in any part of that will cause rapid wear of the seal. This article has excellent information about it: https://www.sonnax.com/tech_resources/186-chrysler-rwd-valve-body-linkage-pivot-wear Knocking sound during braking isn't something I'd associate with a valvebody...but if you're certain it's coming from the trans, and it continues when the car after all rotation has stopped, could be something in the transmission I guess. Maybe something about it letting go of the front band/clutches? Fluid level being low can cause shifting problems, of course, but nothing like that happened to me when mine ran low. I wouldn't race down the transmission internals path until you've looked over all rotating driveline components. Remember the pump is still turning at idle, car stopped. Also, essential to make sure your throttle valve rod/linkage to trans is correctly set. Lots of guidance out there on that for the 904.
	76 Grem X 258/904,4.0 head/MPFI, Comp X250H cam, Hughes springs, Clifford header, serpentine swap.