johnson qd-10

[dantheman1124]

i have a 1949 johnson qd-10 10 hp motor. the motor was given to me by a friend. it runs ok until you get into high rpm and then in slows down and boggs out. and suggestions on what could be wrong with it? thanks dan

 

[JB]

Re: johnson qd-10

Could be overheating or running low on fuel.

 

[F_R]

Re: johnson qd-10

What kind of work has been done on it? It is kind of amazing that it runs at all unless the coils have been replaced. The original coils in that motor gave much trouble and were obsolete 40 years ago. Then the challenge would be to find something else that would fit in there and work. I used to use lawn mower coils, but no longer remember which lawn mower.

 

[dantheman1124]

Re: johnson qd-10

i have no idea what has been dont to the motor. i know it has gas. i have a full tank. the ratio is 50 to 1 on the gas. i have one of those old metal tanks. i cleaned it out and put new gaskets on it and the motor still does it when you first start it so i dont think it is overheating. the waterpump is working fine bc i see alot of water spitting out of that little whole

 

[wbeaton]

Re: johnson qd-10

The correct mix is 24:1. You should probably change that impeller too, even if its pumping well. Who knows how old it is and when its going to fail.

On to your question...

I have one that does/did the same thing. The coils tested fine on my Steven's tester, but the condensers were shot. I've replaced the condensers, but have yet to run it on a boat. I expect the coils on mine are failing under load even though they test ok. Yours probably are too. I know some guys knock the newer style coils off the laminations and mount them to the old laminations and they work fine. However, that is too much work for me. The other QD-10 I have has had the entire magneto changed over to the "newer" style and it works great. That would be my suggestion. Of course, you could try Twin City http://tcoutboard.com/ they sell used coils and condensers.

I wish FR could remember which lawn mower coils he used to use. That would be incredible.

 

[dantheman1124]

Re: johnson qd-10

i guess it might run better with the right mixure too. How hard are the condensors are to change. where exactally are they at? how do you change them. i know alot about cars and i work on them ALOT but i am new to the whole boat thing.

 

[wbeaton]

Re: johnson qd-10

Coils and condensers are located under the flywheel. They are simple to change. You just undo two screws and it pops off. However, removing the flywheel will require using a flywheel or harmonic balancer puller and a strap wrench. The old style condensers are no longer available, but you can use the newer style. You may have to modify the armature plate slightly to accomodate them.

 

[JB]

Re: johnson qd-10

Well, 50:1 is your problem. It is overheating from underlubrication.

Run her on a tank of 24:1 and my prediction is that she will do fine.