1987 Mercruiser 3.7 shifting problem

[muskiefishhead]

This is my first post and want to say thanks in advance to all who post here as I've learned quite a bit but have not found the answer I'm looking for.

I took the boat out the other day after having a Merc mechanic do some work. I had the engine water pump seals relaced and a new lower unit impellor installed. It started fine but when I shifted into reverse to back away from dock and then put it in neutral, the boat stayed in gear and wouldn't come out of reverse. I ended up almost hitting the dock going backwards before I could monkey around with the shifter and it luckily came out of gear but only by working the shifter back and forth repeatedly. When I put it in forward it went in Ok but when I put it back into neutral, it wouldn't come out of forward gear. After monkeying around with the shifter it eventually came out of gear. Every time I'd put it forward or reverse, it would stay in gear and only come out when I'd work it in the opposite direction. I really had to work the shifter and squeeze the handle to get it to go into the other direction as it would stop in the neutral spot but acted like it didn't want to go in the other direction.

I've read some posts that say I may have caused this to happen by tidying up some of the wiring and cables in the back of the boat after I installed a couple new transducers. I did loosen up all the cables, etc. once I got home and haven't had a chance to try it again but I'm wondering if by some chance some of this shifting problem could be related to the lower unit impellor work I had done? Could this be a result of the lower unit having been pulled off and the shift lever/linkage not be properly aligned when it was re-installed?

Sorry for the long post but I wanted to give all the details to help with any diagnosis. Thanks in advance for any help or advice which would be greatly appreciated.

[stonyloam]

If it is shifting into gear properly, it would seem the shift cable is OK. Not coming out is a symptom of the shift interrupt not working properly. Read this post by Don, gives a pretty good explanation of how it works. http://forums.iboats.com/showthread....49#post1930449 Good luck.

[Eric 3.7LX Alpha 1]

agreed.

You are able to shift into forward and reverse, can't get it out of gear, maybe the wires to the interruptor are disconnected.

That link from Terry should get you on the right track.

When you shift out of gear, have someone back at the shift bracket on the engine and see if it is moving off center, which it should to cut off the engine for a split second, allowing you to shift.

[dubs283]

When you shift out of gear, have someone back at the shift bracket on the engine and see if it is moving off center, which it should to cut off the engine for a split second, allowing you to shift.

don't need a helper to see if the shift interrupter is working

with the engine running at idle in neutral, press the v-notch assy down - does the engine stumble/die?? - if so the shift interrupter is working

you may need to adjust the arm on the switch, but most likely if the switch works you are in need of a new v-spring

the new v-spring is much stiffer than the old ones and has yellow on the ends - bout 5 mins to install

[bifflefan]

While it may be the interupter, I think it more likely the lower shift cable is not adjusted correctly or is streched.
I would look at both. Mine used to hang in gear and the interupter seemed to work but not correctly. After adjusting the lower cable it all works as intended.

[dubs283]

After adjusting the lower cable it all works as intended.

there is no "adjustment" for the lower shift cable

it is "set" at 6 inches in forward gear at installation (back off four turns for non-shift assist equipped engines)

if you need to "adjust" it - it either wasn't set properly upon installation or you need a new cable

the OP's problem is a textbook interrupter problem - the drive isn't going into neutral - they need to inspect/troubleshoot the shift interrupt system

[stonyloam]

there is no "adjustment" for the lower shift cable

Actually there is, starting on page 89 here: http://www.perfprotech.com/store/app...ift-adjust.pdf It also deals with the proper adjustment of the shift interrupt switch.

[dubs283]

Actually there is, starting on page 89 here: http://www.perfprotech.com/store/app...ift-adjust.pdf It also deals with the proper adjustment of the shift interrupt switch.

that is for adjustment of the REMOTE shift cable, not the drive unit (lower) shift cable

[stonyloam]

that is for adjustment of the REMOTE shift cable, not the drive unit (lower) shift cable

Apologies, you are right. The adjustment does affect the shift interrupt, and may help.

[bifflefan]

there is no "adjustment" for the lower shift cable

it is "set" at 6 inches in forward gear at installation (back off four turns for non-shift assist equipped engines)

if you need to "adjust" it - it either wasn't set properly upon installation or you need a new cable

the OP's problem is a textbook interrupter problem - the drive isn't going into neutral - they need to inspect/troubleshoot the shift interrupt system

Exactly as I said, you need to make sure the cables are adjusted properly first.

[EddiePetty]

........ I may have caused this to happen by tidying up some of the wiring and cables in the back of the boat ......

As well you may have !!!

If you altered the routing of the lower shift cable and placed it in a bind, the cable may not allow the switch to operate.

Remove the lower cable from its bracket, and with the help of an assisant to spin the prop, push in and pull out on the cable to check for ease of operation. If resistence is noticed, 'un-tidy' the cables you rearranged and again check the cable operation.

[muskiefishhead]

Hi,
My thanks to all of you who replied. I'll try all the suggestions tomorrow but first I'll see if UN-tidying up the cables will solve the problem. I'll reply back with/if the problem goes away after trying all these things. Thanks again....

[dry dock]

had the same issue with mine but i just needed to idle my engine down lower works fine now . my shift inteupt is disconected...... good luck.

[Eric 3.7LX Alpha 1]

had the same issue with mine but i just needed to idle my engine down lower works fine now . my shift inteupt is disconected...... good luck.

Shifting without the interruptor connected and working can be dangerous and not good for the drive, cables, or shifter.