Mercury overdrive won't go into reverse

M

mcgarrett

Well-known member
A friend had a local shop install a Mercury Borg Warner overdrive into his '50 F1 pickup and had been working flawlessly until he took it to another shop to have a leaky rear seal replaced. When he got the truck back, it will not go into reverse.

I've rebuilt many of these transmissions in the past, but it's been a few years so I'm a little fuzzy about potential problems like this and all of my BW repair manuals are packed away while we are waiting to move to a new home.

The shifter moves the lever on the side of the trans into position as it should but there is no engagement with the reverse gear - all other gears operate properly. Short of pulling the transmission, any ideas of things to check externally? The overdrive cable moves in and out normally and is all the way back against its resting position stop when pushed IN.
Do I remember correctly that there is a reverse lockout switch or some kind of control that might be out of whack?
Appreciate any helpful advice.
 
I didn’t get your phone message till after hours yesterday. I will forward a link to the rebuild I did several years ago on the 49 Merc overdrive transmission. I’ve given it some thought and honestly this is nearly impossible to diagnose from afar. The one question I will leave you with is this……with the transmission in neutral and the control cable disconnected from the lockout lever, how does that lever feel when you move it forward and backwards? Normally, it would be spring loaded and behave with a “cam over” function. For example, if you pull it forward (against spring tension) it should remain in its forward position. Then if you nudge it towards the rear, it should take over and pop itself against the stop by itself. If you can easily flop the lever back and forth with little to no resistance, the lockout shaft or another component are either broken or improperly engaged inside the tail housing.

If the lever behaves normally, there is something else going on and a proper inspection would be in order.

The big question I have for you is…..did your friend discuss this with the repair shop, and if so, what did they say or offer to do?
 
Mac,
Appreciate your tips on this and I think you might be spot-on about the operation of the lockout cable lever. They more I think about it, that seems to make sense. I'll check it to confirm. My friend was so angry with the shop that worked on it that he took the truck without settling the issue with them. The shop wasn't qualified to work on it in the first place and I'm pretty sure they didn't reassemble it correctly, but we'll move on and get it repaired properly. Thanks so much for your valuable feedback.
 
Sounds like your pawl on the soliniod is not dropping out to allow the rail to depress or slide as it were. When you put the lever in reverse the rail controlled by the lockout arm has to move back . It can't do this if the pawl is pushed in. Pull the niod out it should come out about 3/8" then require a 1/4 turn to release it. if it just comes out it was not ingauged and was holding the pawl in. Tim
 
pistonbroke said:
Sounds like your pawl on the soliniod is not dropping out to allow the rail to depress or slide as it were. When you put the lever in reverse the rail controlled by the lockout arm has to move back . It can't do this if the pawl is pushed in. Pull the niod out it should come out about 3/8" then require a 1/4 turn to release it. if it just comes out it was not ingauged and was holding the pawl in. Tim
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Yes, you also have a good point there and I will check it as soon as I can. It could be something as simple as that...sure hope so.
 
The transmission has a lockout device as part of the reverse shifting mechanism inside the transmission gear section. It pushes the rail back so that a person doesn't have to pull the lockout cable. It won't function in reverse unless it's locked out.

If the last person to work on it removed the tail housing, I would wonder if it was put back together correctly. There is a small cover plate on the top of the tail housing that has to be removed to get to the snap ring that holds the shaft assembly. I just wonder whether he was experienced on that transmission. It has a specific way of removal and reinstallation of the housing and that could have been problematic if it wasn't done per the procedure. With the right tooling, the housing doesn't need to be removed to replace a seal. I think there was even a tool to pull the bushing if it was worn but I don't know without being there just what may have happened.
 
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rotorwrench said:
The transmission has a lockout device as part of the reverse shifting mechanism inside the transmission gear section. It pushes the rail back so that a person doesn't have to pull the lockout cable. It won't function in reverse unless it's locked out.

If the last person to work on it removed the tail housing, I would wonder if it was put back together correctly. There is a small cover plate on the top of the tail housing that has to be removed to get to the snap ring that holds the shaft assembly. I just wonder whether he was experienced on that transmission. It has a specific way of removal and reinstallation of the housing and that could have been problematic if it wasn't done per the procedure. With the right tooling, the housing doesn't need to be removed to replace a seal. I think there was even a tool to pull the bushing if it was worn but I don't know without being there just what may have happened.
Click to expand...

Appreciate your feedback on this. Looks like he will need to have a competent shop do an R&R to determine the actual cause. If I had a workshop and my tools available I think I could find and remedy the problem.

Many thanks to all with your replies and suggestions. :)
 
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