1987 Johnson 150 GT will either go into forward or reverse but not both!

[planty32]

I have a 150 Gt on my bass boat and the motor will either go into forward or reverse but not both.
it has new shift cables and I have tried everything to adjust the shift rod but still no luck. I put a hot foot on the boat thinking the extra throw in the sifter would help. I can get the boat to go into forward and sometimes reverse now. But it will slip out of reverse very easily when any throttle is applied. I also had someone take the lower unit apart and inspect the gears and they said it was fine. My guess is all the linkage is so worm out that that it has to much play. Is there a way to solve this issue?

 

[emdsapmgr]

You did not mention setting the shift rod height. The factory service manuals have a very specifc measurement used to set the shift rod. It screws into the lower unit and the height is set by twisting the rod up/down. The measurement is taken from the flat top of the lower unit to the centerline of the eye at the top of the shift rod. Once that it set-that is ideal. Once the lower unit is shoved up in place and bolted, you may need to adjust the shift cable slightly to insure correct engagement for both forward and reverse. Before bolting in the end of the shift cable, I like to manually shift the lever inside the cowling to insure it goes into forward/reverse. Once you know if shifts OK manually, you can put the lever in neutral, then put the control box in neutral also. The eye of the shift cable end should match up perfectly with the stud on the engine's shift lever. If not, you may have to slightly adjust the screw/trunion in order to get the cable eye to match the stud.

 

[planty32]

I have tried the factory spec for the shift rod that is stated in my manual. Cant remember the specifics exactly. I have had the lower unit off a number of times to adjust the Shift rod up and down and still no luck. We all know the bolt connecting the top of the shift rod to the control can be a pain to take in and out. I have tried every possible adjustment combination with the shift rod and shift cable and still not luck...

 

[interalian]

If your shift rod height is corrrectly set, start looking for lost motion. There are plastic bushings in the shift arm. How much play fore and aft do you get on the shift cable connector bracket when the cable's off? How much play are you getting in the cable itself? Have you looked inside the control box to see if it's worn?

 

[emdsapmgr]

If you have the shift rod set to the correct height, you should be able to disconnect the shift cable at the engine, and then shift it by hand (manually) while the engine is running. What happens when you try to do that?

 

[planty32]

I will check all the bushings and the control box for any play.
I will also take the boat out and see if I can shift it by hand. Ill let you know how it goes. Thanks

 

[emdsapmgr]

You can shift the engine while running it in the back yard on the trailer. Esp check the nylon bushing that the shift lever rides/pivots in. Just below the bottom carb. There are two sizes of this nylon bushing, depending on the engine. Difficult to find those bushings on the factory parts diagrams.

 

[Silvertip]

There is more to check and adjust before getting into the control box. Just twisting away on the trunion adjustment is also not the correct way to adjust the cables. So quickly - it goes like this:
1) Disconnect the shift cable at the engine.
2) Manually move the shift lever on the engine to NEUTRAL
3) Place the shift/throttle control in NEUTRAL
4) Without pushing or pulling on the cable, bring the end of the cable up to the attachment point on the shift lever.
5) Adjust the trunion so the connection can be made without pulling or pushing.
6) Go boating.

This is of course not a valid adjustment procedure if the shift rod height is not set in accordance with the service manual.
And just so you know, the throttle cable is adjusted the same way and must always be disconnected when performing link&sync or idle speed adjustments.

 

[planty32]

Sorry it's been a while work has been crazy busy. I had some time to I tore the lower apart myself to have a look. I found that where the cluch dog meets the reverse gear is rounded off. Could this be causeing the motor to jump out of gear?

 

[emdsapmgr]

It's a fact that when gears get rounded off, they tend to slip out of gear more. Moreso in forward, as that is where all the hp is applied. Less in reverse, as it's usually a low hp shift.

 

[planty32]

Here is a picture of the Gear.

 

[jakedaawg]

Lucky you, time for new clutch dog and gear. Better disassemble and check forward gear also.