Wont go into gear

[pass118]

My 87 Force 125 will not go into gear. The Driveshaft on my lower unit snapped in half so I found a second hand lower unit and upon inspection it seemed to work fine as I spun the prop in forward and reverse the driveshaft spun also and I filled it up with new oil. So I installed the lower unit today and as I went to put the boat into forward it did nothing but rev out. I put the boat in gear ( while not running) and the prop spun but the flywheel didnt. Does anybody have any suggestions on what to look for? Is there a clutch or something at the top of the driveshaft thats not engaging it? Thanks..

 

[Stavie]

Re: Wont go into gear

I"ll be happy to help pass118 but I need a bit more info.

If you have the engine model number something like 1258f7a will help me find the right schematic.

If you don't have it at the moment no problem.

Did you break the prop shaft in the lower unit?

Or was it the drive shaft from the power head?

Check your cables first and or disconnect one and manually try to engage F/R
much like you tested the L/U `in your post. There in no "clutch" instead there is a dog gear which slides along the prop shaft when pushed forward or reverse via the shift rod moving up and down. Let me know how that turns out .

 

[pass118]

Re: Wont go into gear

Yea Stavie iy was the shaft from the powerhead to the lower unit. 1251x7b is the serial number. I actually popped the pin out from the controls connecting to the lower unit and pushed the rod down and nothing then up and the same. Thanks for the help..anything that you can think of would be great.

 

[pnwboat]

Re: Wont go into gear

Sounds like something is out of adjustment. A manual gives you the adjustment procedure. You stated that you popped the pin out from the controls? Where exactly was this pin? There is a small vertical shaft on the lower front portion of the motor with a hole in it for a pin. Is this what you're talking about? That vertical shaft is threaded into the shift mechanism in the lower unit. It may have come loose. If so, moving it up and down will have no effect. There should be resistance when pushing it down, or pulling it up. If no resistance, it's probably come loose from the shift mechanism inside the lower unit.

Item 46 in the diag is the rod. Only top 2 or 3 inches are visible outside the motor. It is screwed into item 45, the coupling assy.

http://www.crowleymarine.com/mercury_parts/1245/90.cfm

 

[pass118]

Re: Wont go into gear

Yea item 46 on the diagram is area that I had tried to push up and down manually and there is resistance. When I had the lower unit off and was pushing the rod up and spun the prop the driveshaft spun also and neutral it didnt then down it spun. Even with the controls connected to the rod it pulls it up and pushes it down but theres just no click into gear. Its almost like the driveshaft isnt spinning or connected tp the upper unit.. I'm lost

 

[Stavie]

Re: Wont go into gear

Ok pass look for my post later tonight I think I may have an answer or at least a way for you to test it and find out exactly what it is.

 

[Stavie]

Re: Wont go into gear

Background: This might help understand how the L/U actually goes into F,N,and R. I'll try my best to post a short animation of the process.

Ok like pnwboat had said the rod attaches to part # 45, but here is they VERY important part ( which sometimes falls off of part #25 if the lower right Phillips head screw is removed along with it being the pivot point for part 45) look for # 73 (yoke) it completes the connection from 46 to 45 onto 73 then 25. If 46 has ever been pulled up or down to far it can a will slip off the yoke, or cause the yoke to slip off 23.

There should be resistance when pushing it down, or pulling it up. If no resistance, it's probably come loose from the shift mechanism inside the lower unit.

If you have the tools this isn't a huge problem but does require some mechanical know how. Now if somehow it has become disconnected you have to disassemble the L/U (sorry). Definitely get a book and or ask a marina/mechanic to pull it apart for you , that you might save some cash ans resemble it yourself if you want to. If everything checks out as far as the linkage being connected ,cables are correct and so on the L/U will have to be broken down to find the answer.

For now if the L/U isn't off pull it then with it laying down prop towards the sky.( the reason will be clear in a minute)

First spin the prop slowly and try to pull/push the shift rod like you first did.

Noting ? next turn the prop again while pushing the shift pin down ( that should be forward) feel/hear anything .

If it is still in neutral take a rubber mallet and very lightly tap the prop nut once or twice and then turn the prop anything? By tapping it you can (sometimes) get the dog gear to slide and engage forward. Anything else would requires a specific questions or actually having the L/U in front of me.

Good Luck

 

[Frank Acampora]

Re: Wont go into gear

The first question I want to ask is DO YOU HAVE A 25 INCH SHAFT ENGINE?
and second --did you buy the correct length shaft lower unit?

If you have a 25 inch engine and bought a 20 inch lower, then the drive shaft will miss the crankshaft by 5 inches. Thus, the lower will go into gear but the prop will not turn with the engine running. The lower unit will bolt up with no fuss because the shaft is too short yet everything else is the same and will connect.

If your engine is a 20 inch and you bought a 20 inch lower, or a 25 and you bought a 25 lower, you should have needed to wiggle the drive shaft and turn the prop a bit to mate the splines while installing the lower unit. If you did not do this, either the shaft is too short (25 inch engine leg with a 20 inch lower) OR you have not properly located the splines inside the crankshaft. I have never tried to install a lower this improper way so I don't know if it is even possible.

The other thought that comes to mind is the condition of the crankshaft splines. They should not have stripped if your shaft was a necked-down shaft. That is the reason for the narrower neck. It is a built in weak spot to protect the crankshaft splines.

While I have written in the past that any lower unit from any Chrysler or Force 3 or 4 cylinder engine (with the exception of the 3 cylinder 70 HP) is interchangeable from 1980 until at least 1990, Just the fact that I need to ask the question means that the statement should be modified to include shaft length.