coupler quandry, where to go from here

[ohmthis]

I got a new to me boat last spring with a damaged (from not winterizing) engine. I replaced the engine, coupler (it was cracking), gimbal bearing, and usual maintenence items. We used it all last year with no problems. This spring I pulled the drive to inspect the bellows, gimbal bearing, and check alignment (spot on). We used it a few times, again no issues. My wife went to use it this past weekend and it started, but died and would not restart. After opening the hatch she said she smelled smoke, smoked coupler. I pulled the drive, bearing is fine, drive spins freely in both gears, and the alignment is still perfect. What could have gone wrong? My thought is she started it with drive up and put everything in a bind. She says she did have it down, but I caught her trying to start it before she dropped it the weekend before. Thanks!

 

[Bt Doctur]

drive spins freely in both gears, and the alignment is still perfect

Drive DOES NOT spin freely in both directions. the inputshaft is turned clockwise and in fwd the prop turns to the right and in reverse it turns to the left.
There should ne noticeable resistance turning the input shaft because of the impeller.

 

[ohmthis]

What is meant is that I turn the input shaft, the prop turns in both gears with out any binding, skipping, grinding, or any noise. Thanks!

 

[Bt Doctur]

did you find aluminum shards imbedded in the inputshaft, do you see any splines in the coupler

 

[ohmthis]

No aluminum, and I see all of the splines. The grease in the coupler smells like burnt rubber.

 

[UncleWillie]

Starting with the Drive UP is nor recommended but far from fatal. If not in gear it has no load.
If you spun the coupler, the splines may still look fine.
The rubber, that you can not see, between the splines and the engine are slipping and smoking.
Start it up and put it in gear, if the motor tuns but the prop does not, Bad coupler.
Do this quickly because if the drive is not turning, you are not getting and water to cool the exhaust.
You have no longer than ~30 seconds before it starts to get too hot.
EDIT:
Another thought....
Put the drive in REVERSE. Put a socket on the prop nut with a breaker bar.
Turn the prop CW like you are tightening the nut. You should be able to turn the crankshaft on the motor if the coupler is good.

 

[bruceb58]

Put the drive in REVERSE. Put a socket on the prop nut with a breaker bar.
Turn the prop CW like you are tightening the nut. You should be able to turn the crankshaft on the motor if the coupler is good.

Not sure I would do that. You are spinning everything in reverse of normal including the water pump.

 

[alldodge]

I got a new to me boat last spring with a damaged (from not winterizing) engine. I replaced the engine, coupler (it was cracking), gimbal bearing, and usual maintenence items. We used it all last year with no problems. This spring I pulled the drive to inspect the bellows, gimbal bearing, and check alignment (spot on). We used it a few times, again no issues. My wife went to use it this past weekend and it started, but died and would not restart. After opening the hatch she said she smelled smoke, smoked coupler. I pulled the drive, bearing is fine, drive spins freely in both gears, and the alignment is still perfect. What could have gone wrong? My thought is she started it with drive up and put everything in a bind. She says she did have it down, but I caught her trying to start it before she dropped it the weekend before. Thanks!

I don't think it's a engine coupler issue. The alignment tool is going all the way in and there is no issue, slides in nice, comes out nice. I think you have an electrical issue, and the smoke she smelled is from insulation burning.

Will the engine still crank and start?
Also what engine and drive?

 

[ohmthis]

Definitely not an electrical issue, thats my trade and its not an electrical smoke smell. I'm tempted to replace the drive put it in the water and run it in forward and reverse and see what happens..I dont really know a good test for the coupler. I dont want to be out away from the dock and it take a dump!

 

[airshot]

Just a suggestion here......you sure the coupler is installed correctly? Sure you have the correct alignment tool? On my boat I can see the coupler with a mirror and a light, any chance you can?

 

[NHGuy]

If the alignment bar slides in perfectly and the coupler is damaged, either the new coupler was defective or the engine or the transom is moving underway. But the burned rubber smell could also be from the engine if the coupler is not bad, perhaps there's a belt burning on a rusty pulley. Or the rubber exhaust tubes could be cooking if the engine wasn't pumping cooling water. If the coupler is bad it could be a new defect or could have been damaged if the transom flexes too much. Are the motor mounts snug, no engine movement?

 

[alldodge]

Definitely not an electrical issue, thats my trade and its not an electrical smoke smell. I'm tempted to replace the drive put it in the water and run it in forward and reverse and see what happens..I dont really know a good test for the coupler. I dont want to be out away from the dock and it take a dump!

Sounds like you have it all figured out, keep us up to date to your progress

 

[ohmthis]

NHguy, I thought the same things. Belts look good and tight, rubber boots good too, and the impeller has less than 4 hours on it. The mounts are tight, both the bolts that are into the stringer and the stud mount nuts. The tabs are locked in and I put white paint pen marks that have not moved.
Alldodge, im not sure the comment? I've looked this over and have not found anything obvious. I have humbly asked for help, so if you dont have anything to add for help, please don't leave a reply.

 

[duped]

Obvious question...have you gotten the engine to run since? I can't see why a burned coupler would cause the engine to kill. I also can't understand why a coupler would fail out of nowhere under essentially no load whatsoever. She just started the engine and it happened?

I can only tell you what killed my coupler a few years ago. Engine mount dropped down, didn't catch it in time. Few trips later as I'm powering up out of the harbor it totally fails, no smoke, no noise, no nothing.

Pulled the drive and found metal "sticks" in each one of the splines. Pulled the engine and the coupler was stripped bare, no splines left. Not saying the rubber can't spin in the housing, but I bought the cheapest replacement coupler I could find and I haven't had a single problem yet nor have I heard of such issues.

You're posting here to get opinions of the problem. Alldodge is an experienced and very helpful tech and he brought up some valid questions. If you're still adamant it's the coupler, replace it I guess?