Slips out of gear when turning at high speeds??

[hezzy602]

So i was out boating today and my boat seems to be slipping out of gear when i turn at high speeds. I noticed it when i am pulling a tuber or skier. And i noticed it once not pulling a skier or tuber but when i hit a big wave and got a little air born. Right when I'm about half turn the boat is still reving fine but just not in gear, so i have to back all the way off the throttle and then re-engage forward. I just had a problem with not having reverse but fixed that by adjusting the lower throttle cable, could that be the problem, or is it something in the lower unit (clutch or something)?

Boat- 1985 VIP 19' Mercruiser MCM205 262cid 4.3L

 

[-JR-]

Re: Slips out of gear when turning at high speeds??

When mine did that ,i was low on oil in the leg .

 

[CharlieB]

Re: Slips out of gear when turning at high speeds??

That Merc drive doesn't have any clutch, it's manual engagement dogs.

Sounds more like a bit too much trim and ventilating the prop during the high speed turns, backing off on the throttle allows the air to escape and regain grip in the water.

Do you have a working trim gauge?

It the trim limit adjusted correctly or is it allowing too much trim angle?

 

[TilliamWe]

Re: Slips out of gear when turning at high speeds??

What you are describing is classic "blow out" caused by the prop sucking in air and not water. I know it sounds strange, (props don't suck in anything, right?) but think about it for a minute. When you turn or jump a wave, your prop gets closer to the surface of the water. Above the water surface is air. If the prop blades disturb the water enough, they can create a hole in the surface water above, and then the air would "rush in". The air causes the prop blades to overrev and slip against the water. You have to slow down so much to get the prop back down under the water and going slow enough to stop slipping. Just like spinning a tire on snow. You know that flat plate on your outdrive above the prop ( the thing you aren't supposed to step on) that most people call a cavitation plate? Guess what? It's really called an "anti-ventilation plate". And your prop is ventilating. So you either have the drive trimmed up too far, need a new prop, need a prop repair, or you have something wrong with that plate or the drive, or the boat bottom in front of the prop. Or you are just turning WAY too sharp at too high of a speed.

Good luck.

 

[wca_tim]

Re: Slips out of gear when turning at high speeds??

a prop with a little more blade area, especially a LITTLE more diameter and especially a 4 blade with both a little more diameter and an inch or two less pitch for the days when you're hauling more people and pulling skiers, etc...

as an example, I have a 26" turbo that runs great on the top end. behind my 4.3 earlier it was the fastest on top end by several miles per hour AND had a better holeshot than any of my 23" props. However, it's got a smaller diameter and would lose grip in a hard turn, etc... a larger diameter 4 blade hydromotive quad 4 holds like it's on rails - even with 200 horsepower more in the engine compartment. Those are extremes, but illustrate the points made above.

might be worthwhile to pick up a decent aluminum 4 blade (cheapest) if the trim suggestions don't cure the problem.

what kind of a prop do you have on it now?

 

[hezzy602]

Re: Slips out of gear when turning at high speeds??

thanks for all the quick replies!
My prop is defintly chewed up and could probably use a service, not sure what pitch it is, i will have to go back to the storarge and look but i know its a 3 blade aluminum.
I am not trimming up to high at all, it was straight up and down.
The owner before me had a hydrofoil on it but looks like it broke off cause on the port side looks like a big dog took a bite out of it. So now theres 3 holes in that plate above the prop and a fist size chunck out of the port side.
It planes HORRIBLE should i put a hydrofoil back on?? I have heard a lot of mixed reviews on hydrofoils.
I also have a new trim tab on order cause it broke off from the previous owner. Could this also be the cause??

 

[hezzy602]

Re: Slips out of gear when turning at high speeds??

When mine did that ,i was low on oil in the leg .

Whatcha mean "leg"?

 

[TilliamWe]

Re: Slips out of gear when turning at high speeds??

"The owner before me had a hydrofoil on it but looks like it broke off cause on the port side looks like a big dog took a bite out of it. So now theres 3 holes in that plate above the prop and a fist size chunck out of the port side."

Ding Ding Ding, you have your answer! As I said above that piece with the dog bite out of it is your "Anti-Ventilation Plate". With a chewed up prop and a section of that missing, you are going to have ventilation problems.
Fix the anti-ventilation plate. You probably can't put a hydrofoil back on it, cause there won't be anything to attach it to.

 

[TilliamWe]

Re: Slips out of gear when turning at high speeds??

Whatcha mean "leg"?

"Leg" is another term used for the outdrive. Seems to be mostly an English or Australian slang term.

 

[hezzy602]

Re: Slips out of gear when turning at high speeds??

"The owner before me had a hydrofoil on it but looks like it broke off cause on the port side looks like a big dog took a bite out of it. So now theres 3 holes in that plate above the prop and a fist size chunck out of the port side."

Ding Ding Ding, you have your answer! As I said above that piece with the dog bite out of it is your "Anti-Ventilation Plate". With a chewed up prop and a section of that missing, you are going to have ventilation problems.
Fix the anti-ventilation plate. You probably can't put a hydrofoil back on it, cause there won't be anything to attach it to.

You dont think i will be able to put it back on i still got 3 holes to attach to, as long as i get one that will use the same holes, right??

 

[TilliamWe]

Re: Slips out of gear when turning at high speeds??

Sure, you could try to mount it in the same three holes. But don't be shocked if the "dog bite" turns into an "alligator bite" and you lose your nice new hydro foil. I am one who is not a big fan of hydrofoils. I know why some people like them. But I really think it's a bad idea to mount one on an anti-ventilation plate that is already broken.
I am sure others will totally agree with you, and recommend you bolt one back on.

 

[hezzy602]

Re: Slips out of gear when turning at high speeds??

Soo then the solution is going and dropping a chunck of change on a new lower unit casing!?!? And if so, sh*t, i might as well get a totally rebuilt one, i hate this kind of answers, always costing money!

 

[TilliamWe]

Re: Slips out of gear when turning at high speeds??

No, that's not the answer, dumb*** . I said have it repaired. They can be, and are welded everyday. Take it to a prop repair shop, they should know how to do it.