Sticking shift slide?

[nsxandrew]

I have a 1989 Mercruiser 4.3 with continuing shift problems, especially in reverse, extremely stiff to operate and cuts out on interrupter ?kill switch?. This happens both in water and on muffs.

The leg is an Alpha 1 (Gen 1) ratio 1.84, Engine OC623501, 262 CID, 175 hp., Transom OC747189, Drive OC779551.

Over the last 9 months the boat has not been usable, I have had her lifted twice with the following items replaced.
Lower shift cable & bellows ? three times! Upper shift cable, Throttle cable, Remote control unit (Morse)

The leg has been taken off the bell housing and re-assembled several times (always with gear in forward) and with the leg removed the shift cables moves very easily. Both shift shaft and coupler rotate freely, bushes are free with no excessive play, no visible bend or damage, and forward and reverse can be selected very easily. Changing by hand on the removed lower unit seems absolutely fine.

Each time we re-assembled and test on muffs it works OK a few times and then stiffens up dramatically, sometimes won?t go into reverse at all.

Clutching at straws - I am wondering if you have ever known the shift slider (on the lower end of the cable) to jam inside the shift slide cavity which we have cleaned and greased lightly?

Any suggestions much appreciated ? thanks.
Andrew

 

[alldodge]

:welcome: to iboats
Changing font sizes and colors just made it small to read. I copied and changed font

I have a 1989 Mercruiser 4.3 with continuing shift problems, especially in reverse, extremely stiff to operate and cuts out on interrupter ?kill switch?. This happens both in water and on muffs.

Something is not adjusted correctly. The interrupter switch is only used when on the water, it doesn't work, or should not work on muffs

The leg is an Alpha 1 (Gen 1) ratio 1.84,

Engine OC623501, 262 CID, 175 hp., Transom OC747189, Drive OC779551.

Over the last 9 months the boat has not been usable, I have had her lifted twice with the following items replaced.
Lower shift cable & bellows ? three times! Upper shift cable, Throttle cable, Remote control unit (Morse)

The leg has been taken off the bell housing and re-assembled several times (always with gear in forward) and with the leg removed the shift cables moves very easily. Both shift shaft and coupler rotate freely, bushes are free with no excessive play, no visible bend or damage, and forward and reverse can be selected very easily. Changing by hand on the removed lower unit seems absolutely fine.

Each time we re-assembled and test on muffs it works OK a few times and then stiffens up dramatically, sometimes won?t go into reverse at all.

Clutching at straws - I am wondering if you have ever known the shift slider (on the lower end of the cable) to jam inside the shift slide cavity which we have cleaned and greased lightly?

Any suggestions much appreciated ? thanks.
Andrew

Has the drive been removed, inspected and had the water pump or impeller replaced? This isn't so much about the impeller but what did the gear lube look like?

 

[nsxandrew]

Thanks for replying, yes leg was serviced initially with new impeller and oil change, I didn't see the old oil but the technician didn't comment on it.

 

[alldodge]

Thanks for replying, yes leg was serviced initially with new impeller and oil change, I didn't see the old oil but the technician didn't comment on it.

I concerned there is a drive issue and not a cable issue. Who did the impeller change, a dealer of someone else? There are a lot of folks out there that say they are a marine mechanic, but that is in name only

Trying to find out what the gear lube looks like. These drives are not that complicated. If you feel comfortable I would drain the gear lube and let it sit over night, then drain into another container and see if there is anything in the bottom of the pan.

 

[nsxandrew]

Thanks for the suggestion - I will do that. Although there is only 3 or 4 hrs running time on the new oil - I would add that we have tested the gear change by hand almost every time the leg has come off (more than ten times) and it has always gone easily and smoothly - forward, neutral, reverse.

 

[airshot]

With the OD disconnected, have someone move the shift/throttle selector while you push/pull on the the opposite end and see if those parts function correctly. Did a professional adjust the shift cables after installing the new one? They can be quite tricky until you understand just how they work. I remember how much trouble my own was until I had redone it so many times that it finally became clear what needed to be done. The instruction that came with my cable had a misprint and I had to figure it out on my own. Once done correctly no issues (3yrs)

 

[nsxandrew]

Thanks for the comment - yes we have tested in this way. When we first tried this the hand lever (remote) became quite hard to move when resistance was applied to the other ends of the upper cable, done by simply holding cable inner between finger & thumb, as a result of this we assumed the original remote must be worn, so we installed a brand new remote (as mentioned in my original post). We also replaced and re-routed all of the upper cables using shorter 12ft ones instead of 18ft and re-routed them to iron out any tight loops. The whole linkage from remote thru upper and lower cables is now free and easy until the leg has been replaced and a few forward / reverse changes have been tried (while running on muffs). It then suddenly goes very stiff - impossible to shift into reverse - which is why I am wondering about the shift slide getting stuck in the shift slide cavity somehow?

 

[Fun Times]

Since you know there is a pattern to how many times you can shift it before it goes stiff..... Try removing the lower gear housing leaving the upper drive shaft housing still connected to the boat. This may help you with your theory about the shift slide hanging up in the upper housing.

The shifting gears are located in the lower gear housing so you may have a worn out shift spool clutch spring assembly. Basically Item numbers 54 - 60. http://www.mercruiserparts.com/Show_...HAFT%29+%2D+MR

Item number 53 is what turns the clutch assembly to get F-N-R. Item 43 in the following link turns item 53 in the above link. http://www.mercruiserparts.com/Show_...shaft%29+%2D+R

Also ensure the washer (item number 50 in the second link) is still in place and not lost due to past servicing of the impeller. < Very Important.

Keep us updated, good luck.

 

[nsxandrew]

Thank you Fun Times for a most helpful post, I will follow this procedure and report back.

I should mention we are hoping to borrow a "good" Alpha 1 (Gen 1) leg from a local dealer (based over here in the UK) in order to see if that will solve the issue.

I'm also trying to find a large water container (with lid) that will allow us to do a trial run the with some back pressure on the prop.

 

[nsxandrew]

Update - we have borrowed a new leg and fitted it.

This has now worked flawlessly (on muffs) for about 1/2 hour, shifting frequently F/N/R, so it looks very much like our problem must be in the leg itself, or as suggested most probably within the lower assembly.

I now have to decide whether to buy a new lower unit, or whether to have my existing one stripped and re-built.

 

[alldodge]

Suggest putting it in the water to see if t remains ok

 

[nsxandrew]

Thanks for your helpful suggestions AllDodge. It would have been good if I could have tested the borrowed leg with my boat in the water, but I couldn't because the man lending us the new leg wouldn't allow it to go into sea water. It would also have been expensive to get the boat craned in and back out.

I have now had the lower gearcase dismantled by a local repair shop (they said they had to apply a lot of heat to undo the castellated nut). Unfortunately they cannot find any problem, so now we are really puzzled. You mentioned that the shift spool assembly might be worn, how do you check this please?

 

[alldodge]

Your going to need service manual number 6. It has all the info necessary to inspect and rebuild the drive. Below is just the spool but there are other measurements needing to be verified during reassembly

 

[nsxandrew]

Problem finally solved!
After re-fitting the rebuilt leg and finding the same stiffness problem occurring when shifting to reverse, the repair shop guys took the leg away and checked everything again. They discovered that the intermediate shift shaft in the upper part of the leg was very slightly bent, hardly visible but clear when compared to a replacement - fitting the replacement shaft has done the trick and now changing from forward to reverse works well. The shop gave me the replacement (2nd hand) shaft free of charge but I had to pay for 16 hours labour etc.
Many thanks to everyone on the forum who contributed with suggestions - especially AllDodge.

 

[alldodge]

Glad your running, and thanks for letting all us know the out come.

Your comment of the mechanic finding the problem upon the second tear down is typical to hear. They should have found it the first time and doing it twice should have not cost you anything, but so it goes.