Outboard Service

[Dockhead]

I bought a new Mercury 3.5 before going to the Arctic two years ago. It served well there. Obviously not a powerhouse but it did the job required, ferrying people and gear back and forth to shore.


By the next summer, it didn't run well anymore and got worse and worse. Eventually it would not run on the power jet at all. I decided the carb was clogged up, but put off fixing that until just now.


I took it all apart and it was full of some liquid with a kind of oily consistency, and funny smell. Is that what fuel turns into?? The jets did not seem clogged; I gave them a good clean with carb cleaner, polished everything up, and put it back together.


Then I couldn't turn it over. Seized??? Oh, brother. Took the plug out, squirted WD40 into it, and miraculously it freed up almost immediately.


And then -- wonders never cease -- the damn thing started, and I took it out to sea for a bit and gave it a proper sea trial. Seems to be back to normal. Whew.


So now what?


I think it's time to service it. It has very few hours on it so I think I'll leave the impeller alone. Change drive leg oil? Change engine oil? Anything else worth doing on an almost new outboard? I've almost only ever had old ones, so this is a kind of a new experience for me.


And what's up with that fuel? Does it turn to some oily consistency? Or maybe someone poured the wrong something into the gas can? I don't understand.

[Sparx]

If my motor was as you describe I would clean the carburetor, change the fuel filter, change the lower unit oil, change the engine oil. I would at a minimum have a spare water pump impeller on hand. I would also have a spare spark plug on hand.

I would also take the dinghy out and let the engin run hard for at least a half hour. Burn some fuel through it. Let the engine get up to full operating temperature. Then reassess.

[thomm225]

Yeah, engine oil, lower unit oil, and the owners manual recommends replacing the impeller although it is a bit of a pain the first time you do it. (and don't lose the little key if yours has one)

I went almost 3 years without an impeller replacement and then my impeller failed in high traffic when I was coming in one summer afternoon and I had to sail.

The outboard overheated an seized up.

I allowed the engine to cool then test started it. Then I sailed up close to my dock and started the engine to put the boat back into the slip. I kept the cover off the engine for this short period.

Now I try to change to impeller every 1-2 years.

Last time was August 2018 so it needs it now. The Owners manual also say to replace the plug and fuel filter but I went 6 years on the plug and maybe 5 on the filter

My engine is the 5 hp 4 stroke Mercury and it pushes my 6600 lb Bristol 27 when not under sail (and sometimes when under sail)

[carstenb]

Dockhead

Gas can get old -if you've had it in the can for a year (especially if there have been temperature changes) you can easily find that there is thick "toothpaste" and gum in it. Happened to us. WE had a can of fuel we had filled in Denmark and 6 months alter in the caribbean, the outboard died and it was due to a "thick gummy substance in the gas"

as to service - we sold the POS evinrude (we always had problems with it) and bought a Tohatsu ( I know they also make the Evinrude). The manual (you should have one also or else google it) said to change the spark plugs after about 30 hours ( I did ) and first service was (ours is a 2 stroke) change the gear case. If yours is a 4 stroke - change the oil, change the gear case and change the spark plugs - life will get easier.

Since I know you don't sue the outboard during the winter - I would suggest that just you fire it up once or twice each winter and let it run until it is hot. That will ensure the damned thing starts right up when spring arrives

[Dockhead]

Originally Posted by carstenb

. . . Since I know you don't use the outboard during the winter - I would suggest that just you fire it up once or twice each winter and let it run until it is hot. That will ensure the damned thing starts right up when spring arrives

When I kept the boat in Cowes in the winter I did use the outboard all year round. Up here obviously it's different.


I think I'll keep the alkylate fuel in it from the end of the summer and start it up every month or two as you suggest. That ought to keep the cobwebs out.

[Lake-Effect]

Originally Posted by Dockhead

I bought a new Mercury 3.5 before going to the Arctic two years ago. It served well there. Obviously not a powerhouse but it did the job required, ferrying people and gear back and forth to shore.

By the next summer, it didn't run well anymore and got worse and worse. Eventually it would not run on the power jet at all. I decided the carb was clogged up, but put off fixing that until just now.

I took it all apart and it was full of some liquid with a kind of oily consistency, and funny smell. Is that what fuel turns into?? The jets did not seem clogged; I gave them a good clean with carb cleaner, polished everything up, and put it back together.

Then I couldn't turn it over. Seized??? Oh, brother. Took the plug out, squirted WD40 into it, and miraculously it freed up almost immediately.

And then -- wonders never cease -- the damn thing started, and I took it out to sea for a bit and gave it a proper sea trial. Seems to be back to normal. Whew.

So now what?

I think it's time to service it. It has very few hours on it so I think I'll leave the impeller alone. Change drive leg oil? Change engine oil? Anything else worth doing on an almost new outboard? I've almost only ever had old ones, so this is a kind of a new experience for me.

And what's up with that fuel? Does it turn to some oily consistency? Or maybe someone poured the wrong something into the gas can? I don't understand.

The carb thing sounds typical. Were you using gas with ethanol in it? How old was your gas? Used any fuel stabilizers?

For our outboard, I'm a gas zealot. I only buy ethanol-free gas (currently Shell V-Power, their top grade, which has none). I also add gas stabilizer. At end of season I dump any boat gas into my truck, and start fresh in the spring. The net result is that my carb seems to remain almost pristine.

Mine's a 2-stroke; yours is a 4-stroke and reportedly fussier about gas. I believe the little Mercs are actually Tohatsu's.

I've read that many owners of 4-stroke outboards religiously disconnect the tank then run the engine dry before storage, so that there's no gas sitting in the carb. Some even drain the bowl.

Were you flushing the engine with freshwater after running in saltwater? That's recommended. Given the relative youth of the engine, if you can see a good pee stream out the back and it never overheats, the impellor is fine. Our impellor is several years old but hardly any wear on it. We have only used it in freshwater though.

I would change engine oil every 50 or so hours, unless it comes out super-clean; then maybe every 100 hours. Once a season at a minimum. Like with your diesel, it's nice to do the oil change at end of season so your motor sits with clean oil in storage.

Gear (leg) oil? I would either check a little from the bottom screw, or change it now just to see how it is. I did our leg oil after a couple seasons, and the oil that came out was as clean as the oil going in... so I don't worry about it much. But I have heard it recommended that it should be done once a season, mainly to confirm that you're not losing any or picking up water. It's easy, but messy.

What else? I check the plugs and regap once a year. The first tank of the season is new gas, I sometimes add a shot of SeaFoam. I run the engine on a stand (it usually starts first or second pull) and squirt some carb cleaner down it's lil throat while revving up.

Our engine is a 1983 5hp 2 cyl Suzuki and contunies to be reliable under this regimen.

[thomm225]

Next time treat the gas with something like Stabil. It keeps gas fresh for going on 24 months.

I'm at the boat now running last September's gas out of my tanks. I've been trying to use it up the last couple months with short runs.

Also, as part of my yearly maintenance, I flush my engine with fresh water.

I saved my plug when I replaced it with the one that came in the tool kit because the old plug was fine even after 6 years of use.

[Dockhead]

Originally Posted by Lake-Effect

The carb thing sounds typical. Were you using gas with ethanol in it? How old was your gas? Used any fuel stabilizers?

For our outboard, I'm a gas zealot. I only buy ethanol-free gas (currently Shell V-Power, their top grade, which has none). I also add gas stabilizer. At end of season I dump any boat gas into my truck, and start fresh in the spring. The net result is that my carb seems to remain almost pristine.

Mine's a 2-stroke; yours is a 4-stroke and reportedly fussier about gas. I believe the little Mercs are actually Tohatsu's.

I've read that many owners of 4-stroke outboards religiously disconnect the tank then run the engine dry before storage, so that there's no gas sitting in the carb. Some even drain the bowl.

Were you flushing the engine with freshwater after running in saltwater? That's recommended. Given the relative youth of the engine, if you can see a good pee stream out the back and it never overheats, the impellor is fine. Our impellor is several years old but hardly any wear on it. We have only used it in freshwater though.

I would change engine oil every 50 or so hours, unless it comes out super-clean; then maybe every 100 hours. Once a season at a minimum. Like with your diesel, it's nice to do the oil change at end of season so your motor sits with clean oil in storage.

Gear (leg) oil? I would either check a little from the bottom screw, or change it now just to see how it is. I did our leg oil after a couple seasons, and the oil that came out was as clean as the oil going in... so I don't worry about it much. But I have heard it recommended that it should be done once a season, mainly to confirm that you're not losing any or picking up water. It's easy, but messy.

What else? I check the plugs and regap once a year. The first tank of the season is new gas, I sometimes add a shot of SeaFoam. I run the engine on a stand (it usually starts first or second pull) and squirt some carb cleaner down it's lil throat while revving up.

Our engine is a 1983 5hp 2 cyl Suzuki and contunies to be reliable under this regimen.

For years I was using a Mariner 25hp two cylinder two stroke, which came with the boat. From about 2001. I love those old two strokes. I never did anything to it -- changed leg oil once, plugs once, in 6 or 7 years. Never flushed it. Bulletproof. It had electric start which was totally superfluous, since warm or cold it would start with half a pull on the cord. Miss that engine. In those days I kept the boat on a mooring so the Mariner was used constantly and year around, which I guess helps.



I think the problem here must be fuel with ethanol. Just doesn't mix with marine use. I don't think I can get petrol/gasoline without ethanol in Scandinavia, unless I go to an airport and buy avgas.



As to getting gas out of it before storage -- I don't see how it's really possible. Fuel will be left there no matter what. I think I'd do better running a tank of alkylade fuel through it before storage.

[Dockhead]

Originally Posted by thomm225

Next time treat the gas with something like Stabil. It keeps gas fresh for going on 24 months.
.

Will that work even with fuel which is 6% ethanol?

[Tayana42]

Stabil works for gasoline with ethanol but it still doesn’t last forever. I use it religiously but I still try not to keep gasoline for more than two months and if the outboard is going to be idle for more than a week or so I drain the carb.

[thomm225]

Originally Posted by Dockhead

Will that work even with fuel which is 6% ethanol?

Yes.

I use 10% ethanol and have for the past 9 years with this engine which I bought new to replace my 10 hp 352 lb Bukh Diesel

[thomm225]

Originally Posted by Tayana42

Stabil works for gasoline with ethanol but it still doesn’t last forever. I use it religiously but I still try not to keep gasoline for more than two months and if the outboard is going to be idle for more than a week or so I drain the carb.

I'm using 10% ethanol gas now that I bought in September 2019.

No problems, but I do start the engine once every couple weeks all Winter

[a64pilot]

I would change the oil every year as a min, four strokes contaminate the oil with fuel as being raw water cooled they can’t get hot enough to cook the gas off, smell the oil and You will smell gas.
Spark plug, I changed mine about four years ago when the engine went for a swim, not since then, my Honda generator is coming up on 1,000 hours on the original plug, still starts like new. But have a spare of course but I’d be surprised if you need it. This isn’t a two stroke
Change the gear oil yearly, and every few years give it a new impeller, changed mine the first time last year when it was I guess four years old, looked perfect, it’s now the spare.
However pull the foot off every few years, cause if you don’t, you may not be able to, same with the prop take it off grease the shaft and put it back on. Years ago we ruined the seals on a foot using a torch trying unsuccessfully to get the prop off, we never pulled it, and it was completely seized, pulled the prop off the hub with a puller then worked on the hub, never did get it off.
Oh, and grease the screws that hold it onto the dinghy too, and exercise them, they seize into the aluminum part of the motor if you don’t and they seize hard too.
Since it’s being stored over winter, I’d remove all traces of fuel and remove the spark plug and fog the cylinder good, and buy a spare carburetor and keep it, cause I promise you one day you will need it. They don’t always clean up. Even if you have an ultrasonic cleaner, I don’t know why.
Oh, and grease the steering too every year, that also will get stiff if you don’t, use a good quality waterproof grease, around here that’s “green grease”

https://www.amazon.com/Green-Grease-...9150405&sr=8-1
Comes in big tubes too. Whatever you grease the Autoprop with is a good outboard grease.
For some reason the throttle cables usually don’t give too much trouble and I would have thought they would, but lube it once in a while too.

[Dockhead]

Originally Posted by a64pilot

. . . Spark plug, I changed mine about four years ago when the engine went for a swim, not since then, my Honda generator is coming up on 1,000 hours on the original plug, still starts like new. But have a spare of course but I’d be surprised if you need it. This isn’t a two stroke. . .

I hardly changed the plugs on my 25hp mariner two stroke, either. I think CDI pretty much revolutionized that.


I remember buying $40 (money in those days) Beru platinum spark plugs for my old 911S in the early '80's. Platinum! Original spec.

[arsenelupiga]

just buy electric and will have none of these issues. My torqueedo 1000 serves well, needs no petrol or oil. Servicing effort not even worth mentioning. Easy to store inside for passage. No smells.

Setup charging while on davits and will not look back.

It is exceptionally well suited for fishing/trawling. Can go @2 kn for 15 hours or so on one charge.