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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15858
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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Shifted to reverse and went full throttle - could not shift

Customer Question

shifted to reverse and went full throttle - could not shift back to neutral - took apart and stumped
Parts diag shows shift cam (#38 diag 1) which shift rod moves up / down - shift cam has 3 steps for fwd / N / rev and as it moves up and down it looks like it should push cam follower (#52 diag 2) in and out which moves clutch to f/n/r - in other words shift rod moves down, shift cam steps move down which pushes cam follower in which pushes clutch in - That's how I think it should work
In my case the cam follower is attached or stuck on? the shift cam - see pics - when I move the shift rod down it only moves a 1/4 inch up down because cam follower is attached to shift cam and follower hits side of case
I can't figure out how or why why shift follower is attached to shift cam - any help or ideas appreciated
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.
Hello my name is ***** ***** am I speaking with? All Mercurys are cataloged by serial number, can I get that number so I can run it and see exactly what you have.
Customer: replied 1 year ago.
OT358646 - I also have pics if that helps
Expert:  Jason replied 1 year ago.
Got the serial. You can add pictures with the paperclip icon just above the text box.
Expert:  Jason replied 1 year ago.
Okay, to get the shift rod out the pinion nut has to come off first, then the pinion gear will drop, and the driveshaft will come out. Then forward gear comes out. And finally, lastly, the shift rod will lift out. Does that make sense? Do you need the instruction from the Mercury factory manual on the lower unit?
Expert:  Jason replied 1 year ago.
Do you have any other questions on the lower unit?
Customer: replied 1 year ago.
Not trying to take the shift rod out - need to know why shift rod will not move more than 1/4 inch up or down
Expert:  Jason replied 1 year ago.
Did something in the lower unit fall apart? Are all the teeth intact on all of the gears? It looks like the cam follower is still in there, can you reach in there with some long reach pliers and pull that out?
Customer: replied 1 year ago.
Nothing broke - I did reach in there with long nose pliers and tried to pull on cam follower - no luck - It acts like it is tack welded to the shift cam - that's what makes no sense to me - how or why that follower is attached to the cam
Expert:  Jason replied 1 year ago.
That cam follower some more or less just fall out. Do you get any movement on it at all if you shake it back and forth or up and down?
Customer: replied 1 year ago.
That's what I thought - it should fall right out - I got pliers on it tight enough to give a hard pull and no luck - I suspect when I put it in reverse and moved shift lever to full throttle I caused the shift cam to over travel down so cam follower moved to very top of shift cam almost to the roll pin which you can see in the picture - there is some movement if I wiggle the follower side to side - If I pull and push follower up and down it just pushes the shift cam up and down along with the follower
Expert:  Jason replied 1 year ago.
It's going to be that follower that is jamming the shift linkage up. You are going to have to do whatever it takes to try and get that out. See if you can get on it with a piece of wooden dowel and a hammer and try to knock it out. It is going to have to come out either way, however you have to do it. Does that make sense?
Customer: replied 1 year ago.
Yes I knew it was the follower causing the problem but why / how it is attached to shift cam is still the unanswered question - I guess I will just have to take it to the Mercury dealer - I'm afraid I may do more harm than good if I start hammering on it - Appreciate your trying to help even though it seems you are as stumped as I am.
Expert:  Jason replied 1 year ago.
I don't think you can damage it any more than it already is. Sometimes you do have to beat and pound on these things to get them apart. Let me know what they tell you, I would be curious to hear the result.
Customer: replied 1 year ago.
OK - I will let you know
Expert:  Jason replied 1 year ago.
Sounds good, keep me posted.
Expert:  Jason replied 1 year ago.
Good morning. Just checking in, how are you making out with the lower unit?
Customer: replied 1 year ago.
Mercury service manager got the cam follower separated from the shift cam - He said it was "spin welded" - When I went full throttle in reverse the follower must have been spinning at high enough speed and generated enough heat to weld the follower to the shift cam - Once separated you could see the pointed end of the follower was ground / melted flat and pieces of it were still stuck/welded to the cam follower - hard to believe that much heat could be generated considering the lower end was full of oil and in the water at the time but seeing is believing.
Expert:  Jason replied 1 year ago.
I've never seen that happen. If you look at the propshaft and cam follower, the cam follower has a relatively loose fit inside of the propshaft, and although it will spin a little bit it really should not be spinning at the same speed as propshaft rotation. It must have somehow gotten jammed in the propshaft to be spinning at the kind of speed needed to fuse the two parts together. Thanks for the follow up, I do like to hear the outcomes. The website has charged you to speak with me. If you would like to credit me for the time I have spent with you please select a rating for my service. If not, you can contact customer service at***@******.*** if you have any questions about your deposit with them. Thanks and good luck!Jason
Customer: replied 1 year ago.
You asked for me to let you know and I thought the answer to this mystery was interesting - As you know the clutch return spring is pushing hardest when in reverse - I guess the clutch return spring was exerting enough pressure on the follower to make it spin - When he explained it to me the service manager asked if I has ever heard of spin welding - I said not till now! - Agree it has to be 1 in a million but looking at the parts confirms what happened - pics attached - Regards Don
Expert:  Jason replied 1 year ago.
I see the pics. It' just odd that it would do that. If there was no oil in the lower unit because of a leak that would be one thing, with a full lower unit that shouldn't have happened.

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