15 HP Johnson Tiller jumping out of gear

[mduga]

I just got this boat and the motor was working great until it got stuck in some weeds. It uprooted them and caused the water to become really muddy around the motor while it was running. Could this have damaged it at all? It still runs alright, and worked fine until I was ready to come back into the dock. I started it up with no problem. Put it in forward and started to go. Halfway back to the dock, it started jumping out of gear and reving up and then would start going again. It did this 2 times. Do I just need to flush it out or does it sound like a worse problem? I guess I shouldn't have tried to free the boat with all the weeds there. It worked great until then. Any help would be greatly appreciated. I really don't want to take it into the shop already. I have only had it a few weeks, but if thats what I gotta do, I guess I will. I just wanna know if there is a quick fix that won't cost me any money. Thanks guys.<br />-duga

 

[OBJ]

Re: 15 HP Johnson Tiller jumping out of gear

Welcome duga!<br /><br />Not as all bad as you may think. What probably happened is the prop hub spun. The engine reving high and losing forward motion is the clue. Real easy to check, pull the prop off and make a reference line from the rubber hub out to the metal portion of the prop the hub sets in. When you pull the prop off, look at the back of the prop and you can see the rubber hub. Now put the prop back on the motor and go run it until the problem occurs again. Pull the prop back off and check the reference mark. If the marks are no longer in line, the hub spun.<br /><br />The hubs can be replaced by any prop shop or take it to a dealership...most can send them out for rehubing.<br /><br />Let us know what you find.

 

[tashasdaddy]

Re: 15 HP Johnson Tiller jumping out of gear

what year is it. could just be a shear pin if it is older.

 

[mduga]

Re: 15 HP Johnson Tiller jumping out of gear

Not sure on the year. I'm guessing late 90's though. I will try doing this on Friday. How much would you think the new hub will cost plus installation if that is the problem? Or could I install it myself? Thanks for the help guys. Also, where would I look for the shear pin? Thanks<br />-duga

 

[wilde1j]

Re: 15 HP Johnson Tiller jumping out of gear

New prop may be cheaper, check 1st.

 

[OBJ]

Re: 15 HP Johnson Tiller jumping out of gear

None of the 9.9/15's since they came out in 74' had shear pins. A new prop would cost around $75 to $86 depending on where you would get it and who made it. Prop shop replacing the hub around $35 to $50 depending again on the charges.

 

[mduga]

Re: 15 HP Johnson Tiller jumping out of gear

Alright, I guess I will check the hub this weekend and hopefully that's all it is. The thing is, I went all the way across the lake without a problem. Then I shut off the motor to fish for about an hour, and then I started it back up and started to head back in, and that's when it jumped outta gear and revved up. It did that twice, so I just went slow then back to the dock. Seemed like it did it only when I throttled it up quite a bit. I will check this out this weekend. I suppose I actually gotta put it in the water to test it out, and see if it slipped, right?<br /><br />Anyone know a good manual that would help me with maintence and repairs? I am not too familiar with boat motors since I just got mine a few weeks ago. I know they have them for cars, but what about boat motors? Thanks for your guys' help.<br />-duga

 

[OBJ]

Re: 15 HP Johnson Tiller jumping out of gear

A spun hub generally will only let go at high rpms duda....unless it's really bad. Do the test to be sure.<br /><br />If you want just a general service manual, get a Clymers or Seloc...hard to get through sometimes but good for general info. If you want the best manual, get the OEM. Search up Ken Cook Co., or ishopmarine. Both sell reprints of the original manual. If you want the generic, look at the bottom of this page. iboats sell them.

 

[jtexas]

Re: 15 HP Johnson Tiller jumping out of gear

mduga, <br />For future reference if you get some vegetation or something caught on the lower unit, it could restrict the water flow over the hub, causing cavitation - feels just like a spun hub. Lift the motor & make sure the prop's clear. <br /><br />Of course it would have fallen off by the time you got to the dock. Keep your fingers crossed - symptoms might be gone when ya put it back in the water.<br /><br />and welcome to the forum!

 

[mduga]

Re: 15 HP Johnson Tiller jumping out of gear

Well, was out on the water all day yesterday. I still don't know whats wrong. Motor worked fine all the way out. Then we were in a shallower water. There was some weeds, but not many at all. We fished here for a little while. Then we wanted to leave, so we went to deeper water. I throttled it up and it started jumping out of gear again. So we stopped at a new spot to fish. I pulled the motor all the way out of the water, and I didn't see anything plugging the motor or anything attached to it. Left the motor out of the water until we moved again. It worked normal again. I don't understand. I don't think its the hub. I even tryed accelerating pretty quickly from a stand still and it wouldn't slip at all. This problem usually happens when we are moving fairly quickly. Then it jumps outta gear and the boat just slows down a lot and usually water comes flying up the back until I throttle it down and then it will start going again. Sounds like its getting air or something in the fuel line just before it happens. It doesn't leak any fuel or anything, so I don't know where the air would get in there. Any other ideas? Otherwise, I think I will just have to live with it for now. The guy I got the motor from said there was only about 8 hours on the motor, so its not been used too much.<br /><br />Also, there is a knob by the choke that you can turn. What's this do? Just wanna know, thanks again.<br />-duga

 

[wilde1j]

Re: 15 HP Johnson Tiller jumping out of gear

Jumping out of gear is usually a worn clutch dog/fwd gear. Did you check the prop as OBJ suggested for being spun? It's likely one or the other.

 

[mduga]

Re: 15 HP Johnson Tiller jumping out of gear

Ya, I checked the hub, and it was fine. I am just going to take it in. They should be able to fix it at the shop I hope. Hopefully it doesn't run me over $100. Thanks for your guys help.

 

[jtexas]

Re: 15 HP Johnson Tiller jumping out of gear

"...until I throttle it down and then it will start going again." Worn clutch dogs might make it jump out of gear but it wouldn't jump back in.<br /><br />Since you ruled out spun hub, your prop is cavitating - or ventilating, maybe on the exhaust - I'd post the question over on the "Prop Questions and Topics" forum - bet somebody will be able to figure it out. A picture of the prop might help.<br /><br />BTW, (and this is a long shot)...is there any chance you could have a short shaft motor on a long shaft boat? good luck.<br /><br />p.s. that knob is your low speed mixture adjustment - shouldn't need to be changed until you do some carb maintenance or something like that.

 

[OBJ]

Re: 15 HP Johnson Tiller jumping out of gear

"Short shaft motor on a long shaft boat"....now there's a thought.<br /><br />Wonder if the conversion ring is still on the prop. mduga, is the plastic ring still on the end of the prop?

 

[mercrewser]

Re: 15 HP Johnson Tiller jumping out of gear

What does that ring do? I've seen some with, and some without.

 

[jtexas]

Re: 15 HP Johnson Tiller jumping out of gear

You talkin bout the diffuser ring OBJ? It deflects exhaust gas from the prop hub out of the blades...without it you get ventilation - air on the blades is like rowing without having your oars in the water...you can work like mad but you won't get very far. Some props have other design features like a flair at the end or something that does the same thing. I don't understand all the physics of it.<br /><br />mduga what'd you find out?

 

[Scaaty]

Re: 15 HP Johnson Tiller jumping out of gear

I would make sure the Diffuser ring is there on the back of the prop, and just for kicks, what the bottom of the hull look like? Bunch of crap will create turbulence, causing air bubbles, letting the prop cavitate is a possibilty.

 

[mduga]

Re: 15 HP Johnson Tiller jumping out of gear

Wow, i didn't realize anyone else replied until now. I thought you usually get an email when someone replies? Maybe not on this forum. Anyway.<br /><br />About the plastic ring. I didn't see any. No, the motor is for the boat, but I could raise it about 1-1/2 inches so the fin is level with the bottom of boat, but I don't think that would fix the problem anyway.<br /><br />You know where there is a diagram so I can see this ring and see if that's what I am missing? I haven't taken the motor in yet. I used it for a fishing trip 2 weeks ago and I didn't have any problems. Although, with one person in the boat, it barely moves. Must need some extra weight up front when fishing alone. I had the throttle all the way up, and I wasn't moving too fast. Didn't sound like the throttle was even that high either. <br /><br />Thanks for the help.<br />-duga

 

[OBJ]

Re: 15 HP Johnson Tiller jumping out of gear

I added the link to the BRP site duga....click on engine diagrams and follow the prompts. They'll give you a menu for engine breakdown in sections....click on "Gear Case". Look at the prop when you get there. The ring is listed as a "Conversion Ring". <br /><br /> http://www.evinrude.com/en-US/ <br /><br />What it does as the other guys posted, is keep the exhaust gases out of the prop. If your prop doesn't have one, it will look straight around the exhaust end of the prop.<br /><br />Get the engine up on the transom so the anti-cav plate is at least even with the bottom of the keel of the boat. That little 1 1/2" raise will do wonders for performance.

 

[mduga]

Re: 15 HP Johnson Tiller jumping out of gear

Ya, I am pretty sure, mine is missing the converging ring. that diagram was very helpful. should i get one, if it is missing? i will have to check tomorrow to be sure that its not there, but I am almost certain its gone. Thanks for the help.<br /><br />-duga