Stringer revs doesnt move/wont cool

[pete s]

I have a 1977 190hp stringer. Sunday on the way in the engine free reved and would not cool. Was able to do about 1200 rpm without it slipping and got back in. It slips in reverse and forward also when the engine was brought down in RPM so we could move it cooled fine. Lower unit was new last year along with fresh water pump. Prop is also in good condition, hub is fine. If the was a merc I would assume I spun the engine coupler, however not sure this is right direction to look here.... Any help is appreciated!

 

[Scott Danforth]

in order of probability on your stringer:

• upper/lower driveshaft splines (at raw water pump) have failed (common issue)
• coupler has failed
• ball gears have failed
• ball gear splines to shaft have failed

I would start with pulling the drive, splitting it at the pump.

you will need at a minimum, a gasket set and a water pump.

 

[pete s]

I did forget that, the ball gears are good however not sure on splines. Thanks for the input was looking for place to start much appreciated!

 

[southkogs]

I would check your prop too ... just to be sure your hub didn't let go.

 

[pete s]

When it first happened I assumed it was the prop but the no cooling made me think otherwise. I did however remove the prop and put on my spare to rule that out but had the same issue.

 

[Scott Danforth]

if a prop hub goes, you would not loose cooling.

 

[pete s]

Looking at the coupler is the hub in rubber or solid metal? Tough to tell from pics on line.

 

[southkogs]

Yikes! - forgot about the cooling part. Sorry Pete.

I don't know what the innards of a prop hub like this are like (rubber or what), but it does have some sort of "hub" ... friction hub might be what it's called. But the pin can also let go and get things acting funky.

 

[superbenk]

The coupler would be a rubber donut inside a metal bowl kind of thing. The drive shaft slips into the hole inside the donut & the metal bowl around the outside attaches to the engine output shaft. Any burning rubber smells when this happened?

My vote is on broken drive shafts/splines inside the drive. I'd take it off & take it apart. Replace the impeller while you're in there.

 

[Howard Sterndrive]

1977 coupler is solid steel. Not a common failure. If the ball gears are turning, the coupler is fine.

your w/p shaft splines are almost certainly the issue.

 

[pete s]

Well took the upper apart last night. Found a crack in my water pump housing but not much else. The water pump shaft splines are worn but I was expecting them to be completely wiped out. The ball gears are both tight on the shafts. If I turn the ball gear on the engine side the entire engine turns with it. Is it possible that the splines on the water pump shaft were skipping at high load but when I backed off there was enough there to grab? I am still thinking they should show some signs of this.... Ideas???

 

[southkogs]

With the damage to the housing, I'm still leaning toward something going on in that shaft connection ... If the upper is spinning free, and you've got no water in the oil I would still concentrate my efforts in the water pump assembly. Got photos of the shaft?

 

[pete s]

Here is picture of water pump shaft and the housing. Still at a loss on this one. Pulled other ball gear shaft last night no issues there either.

 

[pete s]

[No message]

 

[Scott Danforth]

how do the inside threads of the upper shaft look? those are usually the ones that go. Item 21 if this link works http://www.sterndrive.info/sitebuil...-stern-drive-parts-drawing-upper-gearcase.jpg

 

[pete s]

Well, putting it back together tomorrow with new shafts, impeller, and housing. Any recommendations to use for sealant on the water pump? Id prefer to not buy a whole container of the OMC sealant but will if that is only suitable sealer for the application.

 

[pete s]

Just wanted to say thanks for the help. The driveshaft splines were the issue, even though they were not "wiped" out. Feels great to be back on the water

 

[Scott Danforth]

I used permatex #3

 

[southkogs]

... Feels great to be back on the water

Congrats Pete! Hope ya' have lotsa' good times out there.