OMC 800 stringer slips on long trips?

On long trips, when we get about 7miles or so on her something slips and the rpms shoot up, like a clutch slipping in a car, anyone have any ideas what could be causing this or how to fix it?

i hope it's the prop.

draw a line tru the prop hub run it if the line does not match up it's the prop.

or just put your spare on and try it.

I'm hoping its the prop too, I'm getting a new one here shortly casue the old one and the spare are both chewed so we will see what happens then, I didnt know if there was another common problem with these things slipping like the coupler or the coil

the splines of the vertical shaft that connects the upper and lower outdrive units is the next most likely item to be slipping. especially if the water pump impeller has not been changed every few years since new with a liberal coating of high quality grease on the splines each time.

Well it takes a long time for it to slip and then when we sit and let it "cool off" its fine again for a little while, i figure with splines being worn down it would be a consistant slippage but this is more of an intermittent slippage

It's certainly much rarer occurrence than a prop hub, but the slipping splines can actually get hot enough to weld the metal back together when you stop.

what year is this drive?

Not exactly sure what year the drive is, the boat is a 71, who knows if the drive is original or not.

The 800 was introduced in 1978. doubt you have an 800. probably have an electric shift drive in which case you would have a prop shear pin as well as a friction hub

800 series use 15 spline prop with a hub but no pin

post a pic then we will know for sure.

i will get some pics as soon as i can get back to the marina, prop is definitely not a 15 spline, and it is electric shift

Ok then don't need a pic. So heres the story, not the prop say, cause you may have no rubber on your prop. Then it can be the spring in the lower giving way, in simple terms, there is a spring that grabs, could give way would seem like a clutch slipping.

Could be the water pump shafts, but i don't think so i had that happen to me once they go they spin freely. it can be the coupler, but you have a one piece metal coupler no rubber.

The ball gears how do they look ?

So if the slipping occurs and the boat doesn't overheat, then i would lean towards the spring. See you still have water going to the motor, but if the water pump shafts went you would be overheating real quick no water going to the drive.

coupler went on me too also the motor overheated. And if the ball gears are slipping cause they are real worn down, then it would overheat.

thats the whole deal in a nutshell, it's up to you to take it apart, while your at it check the impeller i would just throw in a new one and housing. Need a cheap place to buy them send me a pm i'll send you the site.

actually all electric shift stringer props have rubber friction hubs in addition to the shear pin.

i should have said if it didn't have a rubber hub, not say it doesn't have a rubber hub.

Still what you think Hy, first the prop if spun if not, the spring ?

I would agree, yes, although not sure why either would go 7 miles before slipping. That's an odd distance for a slipping problem to start at. Usually it's the first 7 feet...

Thats why i was wondering if there was a component that was prone to slipping if it gets hot, like a clutch of some sort.

I bought a used prop on e-bay in the no wake zone was ok soon as i gave it juice to go on plane about 10 mph it would rev no speed.

Knew what it was the second it happened i threw on the spare and the day was saved.

Coupler went i was dead in the water cooled off it still wasn't going nowhere and the temp just shot up.

Splines went was dead in the water temp shot up.

Thats why i posted i hope it's your prop if it's not that, post and we all can talk you thru the next move.