Rusty and siezed - how to free a transmission coupling?
- Thread starter adamv
- Start date
Bummer.
A few questions…
1) Is the boat in the water?
2) what kind of stuffing box do you have?
3) is the prop shaft free to slide back from the transmission?
4) are you planning to replace shaft coupling, prop shaft, anything else?
Normally you would want to remove the nuts, because there is insufficient clearance (I suspect) to drive the bolts out towards the transmission. So that leaves you with moving the shaft coupling away from the tranny.
The shaft will need to be free to slide back some, so if you have a zinc on the shaft in a place that prevents the shaft from sliding aft, you will need to remove those. Same with the stuffing box. It should be loose enough for the shaft to move back. After that, I think you are left with trying to wedge something between the 2 couplings and see if you can drive them apart.
I would probably not want to do this in the water, and I suspect that if the shaft coupling is that bad, you won’t be able to get it off the shaft, and you may eventually have to replace the shaft too.
I did this job a few years ago…fortunately for me, 2 of the coupling nuts had fallen off before I started
.
I struggled more getting the shaft coupling off the shaft. But in the end, I needed to replace the shaft, so I could have saved myself a lot of trouble and could have just cut the shaft in pieces to get it out. This won’t help in your case though, because you still need to separate the couplings.
Good luck!
Greg
A few questions…
1) Is the boat in the water?
2) what kind of stuffing box do you have?
3) is the prop shaft free to slide back from the transmission?
4) are you planning to replace shaft coupling, prop shaft, anything else?
Normally you would want to remove the nuts, because there is insufficient clearance (I suspect) to drive the bolts out towards the transmission. So that leaves you with moving the shaft coupling away from the tranny.
The shaft will need to be free to slide back some, so if you have a zinc on the shaft in a place that prevents the shaft from sliding aft, you will need to remove those. Same with the stuffing box. It should be loose enough for the shaft to move back. After that, I think you are left with trying to wedge something between the 2 couplings and see if you can drive them apart.
I would probably not want to do this in the water, and I suspect that if the shaft coupling is that bad, you won’t be able to get it off the shaft, and you may eventually have to replace the shaft too.
I did this job a few years ago…fortunately for me, 2 of the coupling nuts had fallen off before I started
.I struggled more getting the shaft coupling off the shaft. But in the end, I needed to replace the shaft, so I could have saved myself a lot of trouble and could have just cut the shaft in pieces to get it out. This won’t help in your case though, because you still need to separate the couplings.
Good luck!
Greg
Thanks Greg this awesome!
1. Yes on hard
2. Regular packing gland
3. No it is also seized.
4. I had planned on replacing the coupling but then it dawned on me that it is working - other than the obvious, I need to replace the mounts which are in a similar condition so the only real essential step is to detach the coupling flange from the transmission so I can lift the engine a few inches to replace the mounts.
I can only imagine that the corrosion is only holding the two together around the edges. I was wondering whether lightly dremmeling all the crevices would be enough or maybe some heat is needed or a product or a hammer drill (I was wondering whether it would like to meet my SDS hammer drill)
Just be careful banging on the transmission flange….you don’t want to break it, and you don’t want to damage the gears and parts inside the transmission.
Greg
Sounds like a good idea to grind the shaft coupling only and apply more pb blaster between the two surfaces, being careful not to cut & damage the transmission output coupling. Heat is good idea also.
I removed my coupling this week to change a Volvo shaft seal; thankfully, no corrosion on the couplings. Good luck.
As I recall, the flange has a locating lip, that slips into the transmission flange. If the misalignment is bad, that lip could be what is hanging up. Maybe raise the back motor mounts a little to see if that helps...
Thanks! I ended up punching the bolts out with the hammer drill. Got them out - hopefully the flange faces didn't deform- it's hard to tell but I probably wouldn't advise it - I did have an oscillating tool but my concern was that that could also change the mating.
If I was to do it again and I had the time, materials and equipment I would probably fabricate a 1/2" sheet steel plate with a hole with a countersunk nut in it. I would clamp the plate such that the nut and bolt align with the hole and clamp it. Screwing in the bolt would push the seized bolt through. I tried something like this but the metal I had was too thin and it just bent.
If I was to do it again and I had the time, materials and equipment I would probably fabricate a 1/2" sheet steel plate with a hole with a countersunk nut in it. I would clamp the plate such that the nut and bolt align with the hole and clamp it. Screwing in the bolt would push the seized bolt through. I tried something like this but the metal I had was too thin and it just bent.
Thanks yes, it did have a lip but once the seized bolts were punched through it did all just release to my relief!