Spun prop or bad clutch dog?

[f4igrad]

I guess what my co-worker said is true, boats are a hole in the water in which you dump money. I got a rebuilt engine (1973 Evinrude 50 hp) for my boat this weekend and took it out today. It starts up beautifully and runs very smoothly. I decided to really open her up and when it got up to about 3500 rpms, there was a violent thump. I lowered the rpms and it ran just beautifully, took it up to 3500 again and the same violent thump. Tried it one more time with the same results so then I just decided to keep her at 3000 rpms the rest of the time, and the engine was great without a hiccup.<br /><br />Out of the water, I put the engine in gear and turned the prop, it will spin back and forth about a half revolution before it stops...is this normal?

 

[Xcusme]

Re: Spun prop or bad clutch dog?

Classic symptoms of a faulty clutch dog and forward gear. A spun prop will slip under the load, the motor would run and sound normal.

 

[f4igrad]

Re: Spun prop or bad clutch dog?

how difficult is the repair? does it take a while? <br /><br />should I try to just turn the clutch dog around, since I rarely use reverse?<br /><br />one more thing, could it be an adjustment? I mounted the engine and control box and had to route the cables through the rubber grommet in the back of the boat, i think i changed the adjustment on the cables while i was doing it. i didn't think it would be a big deal...should that be something to look at before i open the lower unit?

 

[steelespike]

Re: Spun prop or bad clutch dog?

The thump could be a missadjusted shift cable.<br /> You also may have a worn clutch dog.<br /> It is normal for the prop to rotate as you describe.

 

[f4igrad]

Re: Spun prop or bad clutch dog?

what would be the best way to fool with the shift cable? take it out on the water and adjust from one extreme to another?<br /><br />thanks again everyone, you are all so helpful!

 

[OBJ]

Re: Spun prop or bad clutch dog?

Put it back in the water and shift by hand after disconnecting the shift cable. If it still bumps, I would pull the lower unit and check the shift rod height. <br /><br />If it don't bump when shifting by hand, readjust the shift cable.<br /><br />Did you have the lower unit off or was it off for the rebuild? Most likely so....at least for the rebuild. The shift rod could be outta' adjustment.<br /><br />Have you checked the gear lube for any metal shards or any thing like that?

 

[f4igrad]

Re: Spun prop or bad clutch dog?

i haven't gotten that far, it just did it today on our first "real" voyage onto the lake. it didn't clunk over and over again, just one big one each time and then i backed off the throttle because i was afraid there was some serious damage going on.

 

[Silvertip]

Re: Spun prop or bad clutch dog?

To adjust the shift cable, disconnect it from the shift lever. Put the shift lever in neutral and the control lever in neutral. Without forcing anything, see if the end of the shift cable lines up exactly with the shift lever. If it doesn't, adjust the trunion (threaded part of the cable) until things line up. Attach the cable. Throttle cable is adjusted the same way.

 

[f4igrad]

Re: Spun prop or bad clutch dog?

ok, i will try that before i drop the lower unit. assuming it is the clutch dog, about how many hours of a repair is it?

 

[h_lankford]

Re: Spun prop or bad clutch dog?

don't ask yet!<br /><br />do the simple stuff first. adjust the cable<br /><br />it usually is the simple stuff.<br /><br />if not, worry about that later.<br /><br />just my 2 cents worth.

 

[f4igrad]

Re: Spun prop or bad clutch dog?

another question, is this engine an electric shift or just a normal one? the model is 50373R. I can shift it into first or back into neutral when the engine isn't running, so I am guessing it is just the normal shift. The cotrol box has two cables coming out of it, one appears to be for the idle lever and the other for the throttle control. There isn't an actual shift lever, you can just push the throttle forward and it engages the forward gear or you can push it backwards and it engages the reverse gear. <br /><br />sorry for the noob questions, I am learning as I go!

 

[f4igrad]

Re: Spun prop or bad clutch dog?

^

 

[f4igrad]

Re: Spun prop or bad clutch dog?

ok, forget the above question, i have figured it out. I was playing around with the cables today and now my control box is all messed up. it will shift into forward and into neutral, but will not go into reverse at all. it feels like it is stuck when i am in neutral shifting into reverse. does the same thing regardless if the cable is connected to the engine or not. how could this happen?

 

[rickdb1boat]

Re: Spun prop or bad clutch dog?

Are you slowly spinning the prop when you try to shift into reverse?? Try it while someone spins it(Not running, of course)...

 

[f4igrad]

Re: Spun prop or bad clutch dog?

let me clarify, the problem right now is only with the control box. i don't have the shift cable hooked up to the engine, it is dangling free. it is almost like the gears in the control box have shifted. When I push the lever forward, the cable moves, but when i try to push the lever into reverse then it is like hitting a brick wall. again, this is with the cable disconnected, so it has nothing to do with the engine.<br /><br />on a positive note, i might have found the problem. i noticed that when i spun the prop and shifted by hand, i could shift MUCH further into forward gear than the cable was actually doing. so i am hoping that was the problem, but first i have to figure out what has happened to the control box. i have done a search and this seems to be a very unique problem.

 

[rickdb1boat]

Re: Spun prop or bad clutch dog?

F4<br /><br />Go to the BRP site and head to your motor. They have a breakdown of the remote control that may help you find out what's wrong...For now:<br /><br />

 

[f4igrad]

Re: Spun prop or bad clutch dog?

thanks for the diagram. i have a manual for a 1975 johnson and it has a section on the control box, which is the same as my 1973. It looks like the shift lever engagement on the control box has somehow jumped a tooth, although i have no clue how it happened. i am trying to pull apart the control box to reset the engagement to the correct orientation, but the IDIOT previous owner sunk a hex bolt into the back of the box where the normal screws go, then to get it to mount correctly he ground the head of the hex bolt down, so there is no way for me to get a wrench or socket on it.. If it is frozen in there, I am afraid even a screw extractor won't get it out. For now, I can't get into the box to correct the misaligned gears. Murphy's Law at its worst.

 

[f4igrad]

Re: Spun prop or bad clutch dog?

just an update:<br />i might have skirted disaster...I adjusted the shift cables and took it out today...ran it up to 4500 rpms and it did fine, no clunking at all. Hopefully it will continue to have no problems.<br /><br />One quick question, when I start the engine I hear a quick grind right after it fires up, I am thinking it is the starter maybe? Only does it for a second and the engine runs fine. The controls are in neutral when I start it.

 

[rickdb1boat]

Re: Spun prop or bad clutch dog?

Might try spraying the starter gear/shaft with a little WD-40 and see if this clears it up. Hopefully, the gear is just hanging up a bit and causing the noise....