Ruined an outboard motor?

[Diggs]

Pffft! I'm furious with myself. I purchased (eBay auction) a 1976 4HP Evinrude twin cylinder outboard to serve as backup for one I have that's just finishing a rebuild. It was seized with a little rust in the bottom cylinder as it had not run in years. I pulled the head and side exhaust cover, soaked the pistons in solvent, freed and cleaned them up in place and just before putting it back thought I'd check the rings to be sure they were free. Sure enough one of the bottom rings was frozen (each piston only has two rings). I soaked it some more and eventually tapped on it lightly with the wood handle of a hammer on a plastic screw driver tip. The ring broke! I spent the next four hours on the Internet looking for another. There are no replacements! Unbelievable! The best I could do was a used and heavily scored piston with rings out of Louisiana. Pictures show the rings aren't in very good shape either but that's my only option at this point. Now I've got to tear this engine completely apart - . The crank and rod ends are all needle bearings that have to be hand placed/packed back in place one at a time - pfffft! Frack! Everyone needs a hobby but......

Now - The reason this motor is so popular is that it produces 4HP but only weighs 35 lbs. Less than half of what 4HP engines weigh today. Plus it is a twin cyclinder so it runs like a sewing machine and have the bottom end weedless design for running in weedy waters. I run it on an 18' square-back expedition canoe. Range with its large 6.5 gallon tank is astounding. (Going down the Mississippi River is over 125 miles.) If anyone here is into boating or has resources I haven't found I'm looking for ring set OMC/Johnson/Evinrude part number 0383920 or piston assembly with rings 0432741. Give a shout. It would be appreciated.

@add - I just searched eBay again and did find one piston with rings in Alaska for way too much money but bought it anyway. Not sure why I didn't see it yesterday. Sigh - Now the tear-down begins.

 

[HCHTech]

Now that you've got to rebuild it anyway, it should be brand new when finished. Sounds like a fun project!

 

[YeOldeStonecat]

Jeeze I had one of those, well, similar, think it was the 6 Fisherman model...yeah nice little outboard. Not many 2 cycles left, so many people snagged them up, great for dinghys as they have so much power for their weight.
Just took at look at local market, found a '71 for...(yikes)...$3,200.00.

I have a Tohatsu 6 now on mine.

 

[YeOldeStonecat]

for me...up 85, and west across E Had bridge

 

[Diggs]

Just took at look at local market, found a '71 for...(yikes)...$3,200.00.

I have a Tohatsu 6 now on mine.

Yikes! - Ebay has them every now and then running $600-$700. I looked long and hard at the Tohatsu but they are about 25 pounds heavier and being a single cylinder four-strike people said the vibration was quite a bit more especially at lower speeds.

I've torn this little 4HP all the way down. New piston, rings and gaskets arrive today so it's time to get the hone out and cross-hatch the bores before starting re-assembly. With all the time and extra parts I've put into this I should have just spent the ~$600 for a running unit in the first place. But, I guess I wouldn't have all this fun in the shop.....

 

[YeOldeStonecat]

My Tohat 6hp 4 cycle is smooth, and very quiet, but yes not as smooth as the thimble piston little 2 cycle twins of the old days. Plus the 2 cycles just have more "grunt" per HP than 4 cycles. That, and being lighter, yeah a 6hp 2 cycle dinghy will easily outrun a 6hp 4 cycle dinghy.

Good luck on the rebuild.
I'll be rebuilding my big boats inboards soon, I have a pair of 350's under the rear deck....burn a bit of oil. She's my second home in the summer, spend about 50% of my time living on it...usually go there Thursday nights and stay til Monday morning...go home Monday...repeat the process.every week til end of Oct when she gets hauled.

 

[Diggs]

the thimble piston little 2 cycle twins

I had to get out my old brake cylinder hone. My 3-stone hone from my snomachine days is waaaay too big - heh!

 

[Sky-Knight]

@Diggs But if you bought it working, you wouldn't have gone through it yourself... and once you're done here, you'll have that outboard for 10 years at least without complaint.

Spending more on a working unit just saved you time now, and spent it later...

 

[Diggs]

Spending more on a working unit just saved you time now, and spent it later...

Well said. So far I found a slit on the edge of one of the pistons like an EDM wire cut into it. Have no idea how that could happen but I'm glad I have a piston to replace it with instead of just replacing rings. Also found blocked cooling port(s) and brittle fuel hoses. I suppose I should just get it over and open up the lower unit too. As I get time it's a nice summer project.

 

[Sky-Knight]

Well said. So far I found a slit on the edge of one of the pistons like an EDM wire cut into it. Have no idea how that could happen but I'm glad I have a piston to replace it with instead of just replacing rings. Also found blocked cooling port(s) and brittle fuel hoses. I suppose I should just get it over and open up the lower unit too. As I get time it's a nice summer project.

Yeah, I'd bite the bullet and do a full rebuild now. If the unit is as rare as you say... there's nothing else to be done. More power to you... I despise two strokes!

 

[Diggs]

I despise two strokes!

I hear you. For me it's mostly their noise and smoke/stink I dislike. But with their simplicity and power to weight they still have a place with my toys (but electric is quickly making inroads also).

 

[Sky-Knight]

I hear you. For me it's mostly their noise and smoke/stink I dislike. But with their simplicity and power to weight they still have a place with my toys (but electric is quickly making inroads also).

Yeah, LiFePO packs are very good, and I love the silence of electric.

When I finally get a chance to disconnect and vanish to the corners of the Earth somewhere... the last thing I want to hear is the drone of an engine.

 

[Diggs]

I love the silence of electric.

You need to build your own ebike. A few purchases off of Amazon (or even Aliexpress) and you can do it for a fraction of what I spent on my first ebike conversion. The second one I built started with a cheap $250 (rear) hub kit and a kids mountain bike and has turned into a quite the urban monster yet can do a 40 mile country cruise or/and leave my mid-drive ebike in the dust.

The loudest thing on my ebike is the tires.....

 

[Sky-Knight]

@Diggs

All my spare time for that stuff goes into this mess:


See the support posts holding the roof up in the back? I just got done cutting tube steel from Home Depot, drilling them out, and painting them because the candy cane mounts I bought actually "meant" for this application broke after only 6 months.

Last month the charger quit... blew a diode, fried the capacitor and burned the fuse.

I won't even get into the work that popup needs... not to mention the 82 Chevy longbed behind that closed garage door!

I have too many projects already!

P.S. I'm doing all this when it's 107-115 degress outside!