Bruce Stott and I saw a problem/symptom where no water was spitting out of the outboard, and the engine started getting quite hot and steaming/smoking a little. Never a good sign. Luckily we only got to the end of the dock before we noticed and decided to turn back for more maintenance, so I’m hoping nothing got seized.
The main theories were:
-Water line is plugged with salt/muck
-Impeller water pump is malfunctioning
To start I found an old service manual on the internet for this Johnson 1967 6hp – Here’s a link 52138772-Johnson-6HP-1965-68. On p.179 there’s a paragraph on the “Cooling System” which also says check the thermostat, if equipped. Figure OM4-17 on p.182 gives a sense of the parts (love this old engine because it doesn’t have many parts) and the water tube is specified in Figure OM4-19.
Then I found a short video by 767ambu (https://youtu.be/wmjGFAEiv5k). I liked the simplicity of it because it helped me start wrapping my head around the work, but obviously it’s not enough.
Luckily James from Highland Outboards gives a great 4 part tutorial on changing the impeller that you’ve got to watch:
Part 1 https://youtu.be/Niri5EgQ6nU
Part 2 https://youtu.be/NtGhCnYN_L4
Part 3 https://youtu.be/pm8mg8W39q8
Part 4 https://youtu.be/xxFp5eXS8Bw
You may need some marine parts and you may not find them at the generalist boat stores you normally go to. If you’re near Victoria or Sidney B.C. you could try Sherwood Marine where Dustin Campbell really knows his stuff (email email@example.com). If you’re near Nanaimo B.C. I’d recommend talking to Dean Rispin at Marine Parts Supply (MPS) of Canada (email drispin@MarinePartsSupply.com).
Evinrude Johnson also has online parts diagrams and codes online if you want to research them before talking to the parts suppliers.
The parts and supplies I was looking for were:
1) A functional impeller that fits. Dean at MPS in Nanaimo stocks Sierra Marine Engine and Drive Parts Impeller 18-3001, which replaces OMC 0-277-181, 0-434-424. They come in a pack of 1 for about $20, so I bought 2 while they were there in front of me.
2) Suitable solvent for washing parts (e.g. mineral spirits, brake cleaner or POR-15 Cleaner Degreaser). I didn’t actually need this or get any but I’m sure I will one day. This seems like a great article link for more info http://www.enginebuildermag.com/2007/07/cleaning-engine-parts-in-the-real-world/
3) Proper lubricant for the gears and bearings. I grabbed a tube of Evinrude Johnson Triple-Guard Grease while I was at Parker Marine in Nanaimo. I got a tube for $7.50 but looks like it can go for a bit more online. Not sure if this is exactly the right stuff but it’s waterproof grease and says it can mix with other greases, so I’m hoping the old ’67 won’t be too fussy. By the way it was at Parker Marine’s Johnson museum that I realized my outboard is indeed a Seahorse and started to see some similarities and design improvements in different older models.
(Spoiler alert- there’s still a blockage in the middle of the tube still, after the impeller replacement. It seems to be in the line that runs through the engine block, before it gets to the thermostat which is still bone dry and corroded. So I’ve got to either flush it out, or study the details of Leeroy Wisner’s suggestions for overhauling the water cooling system in preparation for part 4! http://www.leeroysramblings.com/OMC_6hp.htm A big thank you Leeroy!)