First time boat owner - Help with routine maintenance on 1977 Johnson 6 HP Thank you!

[jimwalt]

I'm a first time boat owner and would like to take care of my boat/motor. I have a 1977 Johnson 6HP. Wondering about the following things -

1. What is the routine maintenance and how often should it be performed?
2. Current spark plugs in motor are L77JC4, but it appears plugs of today are QL77JC4. Which plug is really the best for the 1977 6HP and what is the gap?
3. Oil/Fluid in lower part - What kind and how much? I've read a bit about how to fill it from the bottom and look to see when it comes out the top hole to verify it's full.

Also concerned about the gas/oil mixture in the plastic gas tank. Should I somehow dispose of it and start over? I'm wondering if sludge can form in the bottom, or don't I need to worry about that?

Is it okay to unhook the gas tank to put in my garage after each outing or is that not advisable (hook/unhook)? I just don't want some neighborhood kid to walk off with it in the middle of the night. Also I noticed that 1 time after sitting in the sun for the afternoon the internal suction made the tank start to collapse, which I'm sure isn't too good for it. The tank does NOT have a vent in the cap.

Thank you very much!

 

[flyingscott]

Should have kept this to one post. Change lower unit lube every fall. I would change the water pump now. How old is the gas in the tank? Leaving the gas line disconnected is fine a connected gas line won't stop a thief. 50-1 gas mix. In the sun the tank will swell not collapse it was probably in the shade. The spark plug is the correct one

 

[jimwalt]

Okay I will change the lower lube this fall. Can I ask why in the fall vs. the spring and also what brand/amount do I need?

Gas in the tank is new by me. Only 2 weeks old at most. Mixed with 50:1 oil. I'll start adding the Sta-bil 360 marine in the next tank and using only the Johnson brand oil.

Yes the tank collapsed (sucked in) and looked deformed. I removed the top and that fixed it.

Thank you!

 

[Bosunsmate]

you can buy a venting cap, that suction expansion stress out the system in my opinion.
People generally change the oil before winter because any water left in there from a seasons boating can freeze and irrevociably damage parts

 

[jimwalt]

No Title

Thank you!!! Is this kind okay?

 

[jimwalt]

Thank you. Where could I find a venting cap? The only place I know for boat stuff is walmart, and they only sell a complete tank.

 

[Bosunsmate]

The oil looks good. Not sure where you can buy a venting plug sorry as im sure you dont live near me in the north island of new zealand

 

[Mohawkmtrs]

Try a marina or boat store.