1965 3hp Johnson-- Water Circulation/ Carb Flooding

[Rhodes19]

Hello, I recently bought a 3hp JH-20B outboard as a kicker for my sailboat. Thanks to a lot of previous postings I have replaced the ignition system, re-built the carburetor, replaced the impeller, cylinder head gasket and spark plugs, cleaned out the gas tank and fuel filter (fuel now flows well). I also chased out the crud around the cylinders to improve the water flow. (Many thanks to this posting http://www.outboard-boat-motor-repa... Johnson 3 HP 1952-1967 Tune-Up Procedure.htm)

She now turns over for about 10-20 seconds then dies. The carb floods and only starts with the choke open. Also I do not see any water drops at the relief holes so I am concerned about overheating.

The float valve is shutting off fine; I blew air through the fuel line into the carb and it went through fine and stopped when inverted.

Next week I will replace the orifice plug (part 39) and air silencer plate (part 9); both were missing. Will this solve my carb issues? Also how can I confirm if the water is flowing up to the cylinder jacket? The water tube is clear.

Thank you for any help with either issue.

Rhodes19

 

[Rhodes19]

Re: 1965 3hp Johnson-- Water Circulation/ Carb Flooding

Water Circulation Follow-up: This weekend I tried an idea to check if the new impeller was working (without running the motor). I took off the lower unit and attached my portable drill to the top end of the drive shaft (do not attach to spline or o-ring). I held the lower unit under water and powered the drill (fingers clear of prop!). Water came gushing out of the impeller housing. I then attached the water pipe and water came out at the top. This confirmed that my blockage is in the cylinder/crankcase assembly (CCA).

I had previously taken apart and cleaned the CCA, but on a second pass noticed that I had missed an water passages hole in the top cylinder jacket (I found 3 holes in the cylinder jacket which were filled with crud (top center, mid right, bottom right). I used a stainless steel wire, drill and compressed air to clean (use safety glasses).

Just waiting for my carb parts and will try it again.

Rhodes19

 

[oldcatamount]

Re: 1965 3hp Johnson-- Water Circulation/ Carb Flooding

A piece of weed whacker string works good for unplugging water jacket passageways. I'm always surprised at how far into the motor the whacker string will go. You could also hook a garden hose to the copper water feed tube, remove the thermo stat cover, and turn on the hose. This will flush most of the motor but still run the wire/whacker string through the water jacket passageways (inside the thermo stat housing) in both directions.

 

[bouttime007]

Re: 1965 3hp Johnson-- Water Circulation/ Carb Flooding

I have this exact same motor Rhodes. Im still tinkering on mine.

I guess if your carb is flooding then it isnt your gas cap vent. (forgot to open mine)

Is she getting hot?

 

[kfa4303]

Re: 1965 3hp Johnson-- Water Circulation/ Carb Flooding

Carb may also be flooding due to a stuck float arm needle. Good luck.

 

[Rhodes19]

Re: 1965 3hp Johnson-- Water Circulation/ Carb Flooding

I installed the plug orifice and air silencer plate and either one or both seemed to help alot. It turns out that I did have a plug in there (how did I miss it?) but the jet hole was quite large so I used the replacement part.

It wouldn't start with the choke closed, but came to life when open. I was able throttle up high, but it died when I brought it down below start to idle. Happily no more flooding!

On the second try, I noticed that the cylinders were overheating and shut it down. So no water circulation yet, but I am pretty encouraged. Oldcatamount mentioned there may be a blocked thermostat, but I couldn't find one on my 3hp or in the parts diagrams. Would anyone know where it may be located? I will also try the weed wacker string and hose flush idea soon; thanks.

 

[Rhodes19]

Re: 1965 3hp Johnson-- Water Circulation/ Carb Flooding

Tonight I ran it 3 times briefly in a tank, after having first removed the propeller. I read that the turbulence created in a small tank could keep the water from entering. Well I was very glad to see water drops coming out of the exhaust housing proving that the crankcase assembly is clear and the cylinder temperature while hot, seem ok.

This weekend I was planning on running it for 1/2 hr or so in the tank, then adding the prop and trying it again.

One new thing (which may be due to a missing prop) is that the timing lever (throttle) vibrates over from the 'start' position to 'idle' then stalls. Stays put in the higher range when engaged to the throttle cam arm.

Those last two carbs made a big difference for her. I still don't need the choke to start but that may change with cooler weather. Thanks to all those postings online!

 

[bouttime007]

Re: 1965 3hp Johnson-- Water Circulation/ Carb Flooding

I ran mine in a 6 gal bucket with the prop still on.

The water pick up is pretty low, like 8 inches from the tip of the skeg. I saw water spitting out of the exhaust the whole time, but wondered if it was the right amount. I notitced mine stumbled a bit coming off high idle too. Mine did seem overly warm after 20 minutes of idling, but Im not sure if thats the way they run or not. Im sure I need to replace the impeller regardless.

Glad you got her running better!

 

[Rhodes19]

Re: 1965 3hp Johnson-- Water Circulation/ Carb Flooding

I ran the motor in my trash can w/o the prop to ensure that the water would circulate. The water was moving fine and exhausting out the weep holes. I then added the prop and it worked fine.

I plan to install it on the boat this week. Right now, it takes about 8-10 pulls to startup and I need to use the choke; I expect things will improve with some breaking in.

My $50 motor was a bit expensive in the end. I spent about $140 on ignition and carb parts, $20 on an impeller, $20 on a flywheel puller. Hope this article helps you; it was fun to write.

 

[kfa4303]

Re: 1965 3hp Johnson-- Water Circulation/ Carb Flooding

Glad you got her running Rhodes. Be sure to reset the idle on the lake. The proper back pressure can make a big difference. Tank testing just helps you ballpark idle and hi end performance. You should see a little better water circulation too. As for the timing advance arm, I think there is a nut/bolt you can tighten on the underside of the magneto plate to firm up the action. Try this link. click on the model you have and look at the exploded diagrams, they may be of some help.

http://forums.iboats.com/showthread.php?t=167352
http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1965&hp=3

 

[secretariatslew]

Re: 1965 3hp Johnson-- Water Circulation/ Carb Flooding

For future reference to anyone interested- The 3hp has no thermostat so the water passages are small and like to crud up with deposits. I found the best way was to take the cylinder head off and clear the water jacket out that way. Also from there you can use a pipe cleaner form the base of the block and from the water jacket so you know that water can flow through completely. The only downside is more likely than not you will snap a cylinder head bolt off and have to tap it out. If your 3hp only starts in 8 pulls I would say the low speed adjustment needs to be checked. That always worked for me. If that needle isn't set properly the motor won't even run. I'm guessing you figured it out already though.