Lower unit or shift linkage issue?

[RAM1961]

I apologize if this isn't the right place to post. Picked up a '94 BlueWater 19' open bow with 4.3L mercruiser and alpha one lower. Changed oil in both and took it out for a test run. Everything was fine - planed off, ran well and no funky sounds or vibrations. So I puttered around for awhile, opening it up every now and then, and decided to head back in. Was running great at 3K RPM's - not sure how fast because speedo doesn't work. So pushed it to 3K again, trim down and I couldn't get 10 mph out of it and no where close to planing off, even when I pushed it to 4K RPM's. My first thought was lower unit, but couldn't see/hear any issues and reservoir tank under engine was still at full. Limped in to launch and then noticed shift linkage wasn't acting right. Thought I had it in neutral, but was in reverse. Same going forward. Did finally get it in neutral, but made me wonder if there could be a problem that way. Any ideas where I should start? Thanks in advance.

 

[Texasmark]

Something in your linkage must have come loose. The lower unit is pretty husky and freak accidents aren't common.

As far as linkage, you aren't going to be in reverse and the boat moving forward. You may "think" you are by looking at your help controls but you aren't.

Shift linkage is a twisting function in the lower unit with N in the center and F and R on either side. Not familiar with your 3.0 throttle feed but a locking nut could have come loose or something whereby the helm could be in one position....like your 3 k position but the engine throttle in a different position which sounds like your problem.

Some I/O knowledgeable folks will catch this and probably put you onto the problem. If you don't get any responses, just answer your post, yourself with the word......Bump....that puts it back in the top listing where it's easier to see.

 

[crazy charlie]

Look on top of the engine where the shift cable has a small barrel and slides into a retainer held in place with a small cotter pin.Look for the cotter pin which holds it into the retainer.Sounds like the cable slid out of the retainer.Charlie

 

[TyeeMan]

The boat speed/RPM issue does not sound like a shift linkage issue to me. Your either going to be in gear or not. If the linkage was way out of adjustment and you were just barely in gear, you would likely hear some metallic clicking ratcheting coming from the lower unit as the clutch/shift dogs would not be totally engaging.

If your engine is truly turning 4000 R's and you're barely getting 10 mph, I would suspect either a spun prop hub or a spun coupler hub. If your coupler hub spun you would likely smell burning rubber.

 

[RAM1961]

The boat speed/RPM issue does not sound like a shift linkage issue to me. Your either going to be in gear or not. If the linkage was way out of adjustment and you were just barely in gear, you would likely hear some metallic clicking ratcheting coming from the lower unit as the clutch/shift dogs would not be totally engaging.

If your engine is truly turning 4000 R's and you're barely getting 10 mph, I would suspect either a spun prop hub or a spun coupler hub. If your coupler hub spun you would likely smell burning rubber.

There was no burning rubber smell and it was running fine the first hour. I did notice a slight steady knock when engaging the linkage, even when I first started out with it.

 

[RAM1961]

I took the boat out again on the 4th. Beautiful day on Flathead Lake. Spent about three hours running around at 3K RPM (23.5 mph per my gps app). I didn't have any issues at all with it. I do know the reverse linkage is slightly out of spec since when I put the boat in reverse (at home) and turn the prop until it locks, it doesn't quite get there and clicks. The forward linkage is fine - prop locks no problem.

The only thing I have noticed is a slight knock and it appears to be coming from the lower unit - pull the cover back and can't hear it in the engine, but get on the back deck and I can. Even at idle. Somebody suggested gimbal bearing, but haven't looked into that far.

 

[TyeeMan]

Could be a gimbal bearing, or U- joints. If you have your lower unit tilted too high when it's running you might here some knocking. Perhaps an engine alignment might help too.

 

[hugh g]

I took the boat out again on the 4th. Beautiful day on Flathead Lake. Spent about three hours running around at 3K RPM (23.5 mph per my gps app). I didn't have any issues at all with it. I do know the reverse linkage is slightly out of spec since when I put the boat in reverse (at home) and turn the prop until it locks, it doesn't quite get there and clicks. The forward linkage is fine - prop locks no problem.

The only thing I have noticed is a slight knock and it appears to be coming from the lower unit - pull the cover back and can't hear it in the engine, but get on the back deck and I can. Even at idle. Somebody suggested gimbal bearing, but haven't looked into that far.

A knock does sound like u-joints. When's the last time you pulled the drive to inspect/grease them & inspect gimbal bearing?

I heard a knock in my Cobra one time & it turned out to be u-joints. I lucked out because they grenaded as I was running the boat off muffs in my backyard. If I was out on the water & they let go it wouldn't have been pretty. Pull your drive & inspect them.