Drive or coupler?

[85well248]

Boat is in the water for another few days so I can't pull the drive to check this out fully.

Merc 5.7 with alpha one drive.

Was out yesterday cruising at about 3200 rpm, engine rev'd up high, no noises, smells, or smoke or anything. I shut it down, checked the drive/prop nothing amiss. Started it up, had no forward, or reverse and it got hot quick.

Disconnected the shift cable to the drive, started and manually tried to engage gear, nothing.

I had been thinking it was the drive, and didn't consider the coupler until I started reading some posts.

Wondering if these next items could be related.

Now, I've been trying to figure out an intermittent cooling issue and a lack of WOT issue. wondering if these might be related.

Cooling
At idle the engine will sometimes get hot, if I increase to 1100 rpms or so it'll cool down quick. doesn't always happen though.

This has new heads, carb, manifolds, risers, shutters, thermostat and housing, circulating pump, merc complete impeller, temp sending unit.

WOT can only get it up to 3900 rpm. Didn't seem like there was any noticable slippage before.

 

[85well248]

Re: Drive or coupler?

Too many "ifs". Your going to have to pull that outdrive to figure out what is going on.

I realize I'll have to pull it, hopefully tomorrow i can get it out. I have to arrange for a tow to the launch.

I was hoping though to get more information on the coupler. I've never had the pleasure to deal with them before and didn't know what symptoms are typical when they fail.

Wasn't sure if they could slip, or if it's usually all or nothing.

 

[boat1010]

Re: Drive or coupler?

When the coupler went out on mine there was lots of smoke from the engine compartment. Then when I would start it the smoke came pretty fast when I would put it in gear.

 

[BigBK]

Re: Drive or coupler?

Normally when a couple is "spun" the rubber gets hot fast and you can smell it. I am thinking the problem is in the outdrive.

I agree with Bubba, this same exact thing happened to me 2 weeks ago turned out to be the lower gears. I stipped them clean, and never heard a thing. just the rpms going to 6k. Bob

 

[85well248]

Re: Drive or coupler?

Figured I'd post my findings.

Pulled the boat. Checked for forward and reverse with engine off. It did engage both ways and neutral. In forward stepped on the prop locked up wouldn't budge.

Pulled the drive whole.

Splines good on shaft. Shaft turned but not to prop.

Separated drive found the lower unit shaft sheared smooth just below splines where the o ring goes.

Figured this drive has a lot of service and is kind of shot.
Ordered a SEI replacement.

Thanks for the responses.