Need help with diagnosis.

[shaw520]

88' Searay 230 single 5.7 mercruiser, Alpha 1 gen..... motoring back to our home dock at about 2k rpm, boat full of people and gear, off plane but pushing a lot of water and all of the sudden it felt like it popped out of gear,... brought the stick back to neutral,.trying fwd/rev gears, nothing! Got a buddy to tow me back, removed outdrive expecting to see broken U-joint, nope,.. pulled cap of outdrive to inspect upper pinion gear, everything in tact, drained outdrive fluid, everything normal, no metal or water. Check engine coupler with another outdrive shaft that I have from an old alpha, coupler seems fine. Checked shift cable operation with helm stick, normal. I now have the outdrive on the bench and I can engage fwd and reverse with no gear slippage. WTH??? Baffled,.... what next ??

 

[thumpar]

Look real close at the coupler. The splines may be fine but the rubber could be spun. Check the prop over real close too. Could be spun prop hub. Usually both of those would leave you with a little bit of propulsion but if you weren't super easy on it it would just spin more. If every thing checks out that is all I can think of.

 

[alldodge]

Prop hub, coupler or shift cable

 

[shaw520]

Yes,.,i agree, been looking real close. Ive spun a coupler before noted the smell of burnt rubber and rubber debris. Nothing of that nature. And usually in the case of spun coupler or hub, like you said, you usually get something, even if its minimal, in this case i got nothing, not even the usual clunk when falling into gear. Almost like the shift cable broke, but that checks out fine. Is it possible the shift shoe slipped out of its seat?

 

[alldodge]

Is it possible the shift shoe slipped out of its seat?

Its possible, if something is bent or left off

 

[shaw520]

To check the coupler, i have an old outdrive with a spun upper gear (cap off for visual inspection), so i slipped that on and started her up,..shaft spinning just fine, i even applied some pressure to the spun pinion with a bar to create some resistance on the couple,..feels solid!

 

[Bt Doctur]

Wondering if you forget the SS washer on the lower shift shaft and the brass shoe dropped down.

 

[shaw520]

Wondering if you forget the SS washer on the lower shift shaft and the brass shoe dropped down.

​Possible,... where exactly is that washer Doc ? I never had the lower half disassembled.

 

[kenny nunez]

Since the lower has never been off the only thing as said before is the drive coupling or prop hub. I am betting on the drive coupling.

 

[shaw520]

Since the lower has never been off the only thing as said before is the drive coupling or prop hub. I am betting on the drive coupling.

​Ive separated the lower from the upper before,...but never disassembled the lower.
​So even with all that ive described above you still think it could be coupler,.. I put a good amount of pressure on the blown pinion to create some resistance on the coupler and it held solid

 

[thumpar]

If you had it in half it is possible that the washer isn't on. That would make it not shift on the boat.

 

[Bt Doctur]

Try reinstalling the drive and look at the brass shoe, does it fully engage the upper shoe

 

[shaw520]

Doc,... Ill look at this today

 

[stonyloam]

If you were under power and running and it stopped it is unlikely that it has anything to do with the shift. It is ( starting from the engine) coupler (rubber), coupler (splines), u-joint, gears (upper), verticle driveshaft or spun prop. I am guessing that it is the coupler rubber or prop hub. It will slip under power but friction will hold it in place when you check it by hand.

 

[shaw520]

I have the outdrive back on, and in forward gear I can turn the engine over using the prop and a lot of strength. So I don't think it's a coupler issue. With the screwdriver I tried to physically separate the shift shoe from the foot, no can do. Is it possible the internal roller came out of its Fork,.. the one at the end of the lower shift cable

 

[stonyloam]

The problem is that the gears are undercut a bit (so they stay locked together) and if you were under power when it stopped they should not have just "slipped out of gear". I would still suspect the coupler, it may still be tight enough that you can turn the engine over by hand.

 

[shaw520]

Ok ,..put the outdrive on today a started her up on the muffs,... serious vibration coming from the coupler,... so at this point its def looking like the coupler spun,... and then as the rubber cooled,.. re-joined to the point where its spinning the prop no problem, and holding enough so that I can actually turn the motor via prop Odd though,..ive spun couplers before and there's always been a very distinctive odor of burnt rubber and usually rubber fragments around the shaft,..none of which were present this time..
​Motor pull begins tomorrow.

 

[thumpar]

The power for you to turn the motor over is probably some fraction of a horsepower. Most engines can be turned over by just the friction holding on a v-belt. Your engine is making something around 250 hp. Even at very low throttle it is way more than what you produce manually at the prop.

 

[shaw520]

No Title

Coupler was spun/ melted and then had re-fused itself together. New coupler should be here tomorrow.