Re: only reverse in transmission
....thanks dbarton291 and USMC for the reply. I'll tell you what we did today with this mystery problem. We dropped the valve body and totally inspected it for problems. This 653 must be a later model than what you decribed as it does not have a reverse priority check ball , and the book we have states that newer models do not use the check ball.......so that theory is out. We could not find any broken springs or sticking valves, the body is clean and just looks perfect. The only thing that I felt may be odd is that the one and only check ball that it does have is a fiber ball, not steel. It was not stuck in the veins but to me the ball is not round to the touch and under a magnifying glass you can see the pores etc. Does it seat properly, I don't know. The shop manual doesn't even tell what this ball does. I want to swap it for a steel ball , as I took a turbo 350 apart a couple of years ago with a shift problem and it had fiber balls in it with one stuck, so I swapped with steel balls which 99% of tranny's have and that fixed it. But again, I am abit lost here with this allison . So the valve body looks very good as far as we can tell. Like this thing only has 142K miles (230K Km ), it can't be worn out. I took out the governor and it looks perfect as well as its drive gear. The oil strainer next to the governor is clean also. So overall the valve body looks ok, everything is clean and no filings or debris anywhere in the tranny. Linkage is OK. Now, the other suggestion we had is from someone who has worked on many allison's over the years and he said the 4th gear clutch splines are stripped and seized causing it to be engaged all the time thus giving reverse gear only. Hmmm, well that don't make sense to me. If splines stripped then where is all the filings etc that are gone now ? , the oil is clean, a magnet catches nothing, no burnt smell. no oil discoloration, filter was cut open and is clean, screens are clean. So if the clutch is seized and the shaft turns all the time , then no oil pressure is needed to give this reverse, right ?? if tranny is turning then it should go backwards with no oil pressure ???? , so we figured we'll start the motor and see if the tranny will want to turn with no valve body / oil. Nothing happened, engine running and no indication of it wanting to pull in reverse. So how can the clutch be siezed ? Does this sound logical to you ? The troubleshooting in the book doesn't discuss anything for a problem like we have here. Anyways we can't see what could be wrong. My guess is the fiber ball is maybe a possibility, but gee wiz, to throw the tranny in reverse all of a sudden and stay locked in reverse is weird. That is as far as we went today. Need a pan gasket to put back togeether if we are going to just try it again with just changing the ball to a steel one. But hoping someone can maybe give us another thing to try or check out here. I still am hoping that we don't have to pull the tranny out to get into the clutches that I just can't see why they should be at fault at a snap of a finger when the it went into reverse by itself and won't shift out. Any ideas appreciated, THANKS.
