'82 Johnson 25 HP with tap/knock

[jomishx]

Hi guys. I have an '82 Johnson 25 HP that has ran well for the 3 years i have had it. At the end of last season i noticed a light tap/knock coming from the powerhead. It runs fine and had no other problems but was concerned that it could have sloppy internals. I checked piston play thru the spark plug holes and found no play that i could recreate time after time.
Long story short, i am impatient and found another motor for the boat so i could tear this one down. I have it all apart except the pistons have not been removed from the rods. The seals , bearings, crank, rods all seem very tight and in good condition. Measured journals and all are the same diam w/ no apparent wear, discoloration or corrosion.
Did i make a mistake by tearing it down? Could this light tap/knock normal and i just did not notice it before? The '83 Johnson 25 i am running now does not have this sound. Any help appreciated

 

[jasper60103]

Re: '82 Johnson 25 HP with tap/knock

My '81 25hp sort ticks like a clock. Is this what you mean? I always thought it was normal. In any case it runs great.

http://www.youtube.com/watch?v=gfBQ0_lBkfU

 

[jomishx]

Re: '82 Johnson 25 HP with tap/knock - ticking?

Re: '82 Johnson 25 HP with tap/knock - ticking?

Jasper, thanks for the vid. That really helped and as far as i can tell, that is about the same ticking mine makes. How long have u had this motor and has it always made this sound? Anyone else out there with a Jonson that has ticked for a long time but runs great? Seems odd that i just noticed it last season and have had it for 3 years...

 

[springtuck]

Re: '82 Johnson 25 HP with tap/knock

gotta 99 30hp and in the driveway on muffs you can hear a little knock if your standing in the right spot. Runs like new and no problems. Keep hoping it will blow so I can get an new 4cycle, but no luck. May be a product of it being a two cylinder.

 

[outlaw241]

Re: '82 Johnson 25 HP with tap/knock

could be a crack in the starter paw making the ticking sound if it has a pull start.

 

[jomishx]

Re: '82 Johnson 25 HP with tap/knock

Thanks for the help guys. This is an electric start, but good thinkin. Since its already apart i'm gonna change out the rings, seals and bearing needles and slap her back together. If it still ticks...well, lesson learned. I think it ought to last me quite a few years after this though. Thanks again

 

[G DANE]

Re: '82 Johnson 25 HP with tap/knock

That is piston slop. It clears up some, when is has ran under load at high throttle for a while. They can run a long time with it. Iddling will not get it warm enough.

 

[jomishx]

Re: '82 Johnson 25 HP with tap/knock

Thank you G Dane. This is my first marine engine teardown so it was fun just seeing the way 2-cycles are put together. With the new parts i'm putting in it should run like new and last a long time. I found out the thermostat was stuck open when i dismantled it. At least it wasn't stuck closed. So it wasn't all for nothing. Love learning new stuff like this and this is a great forum for it. thanks to everyone for their input

HAPPY BOATING!!