Outboard Motor Maintenance

[SawyerTed]

I'm getting ready for an extended time at the coast with my boat.  Total, in a year, my boat will spend 3 months in salt water and 1-2 months in fresh water.   The boat gets pulled from the salt water every couple of weeks for an engine flush, wash and bottom scrub. 

It gets annual and regular maintenance done at recommended intervals.   I'm doing the 300 hundred hour maintenance now.  

One task I'm glad I've not neglected is replacing the engine sacrificial anodes.  


The anode ports on a Suzuki DF200A.  


What the used anode looks like.  


Renewed on the left, used on the right.

That's only 100 hours of use with regular flushing and periodic fresh water use.  

The anodes did exactly what they are supposed to do - take the corrosion instead of the engine block. 

Neglect here would mean premature death of an engine.   It's easy to overlook something like this. 

[Magicman]

Some RV water heaters also have a sacrificial anode that must be replaced.

[YellowHammer]

Saltwater is like battery acid, good to stay on top of it.  

Are you disconnecting the batteries when it is in the water and you are not using it?  Those are not the only zincs, are they?  I would think there would be several per engine.  

[SawyerTed]

Saltwater does eat stuff and it's eaten its share of my stuff over the years.  Back during my surf fishing days, I used to get teased for taking my rods and reels in the shower with me.

Battery switch disconnects all but the bilge pumps.  I'm pretty committed to switching batteries off for any overnight stay at a dock.  I also religiously raise the motor at the dock to reduce electrolysis due to stray current from leaky electrical connections. 

There are 5 engine block anodes on a Suzuki DF200A (4 cylinder). In the photo you can see 3 in a vertical row, then there are two more to the left.  A 6 cylinder Suzuki 200 hp has 7 anodes.  

There are the usual external anodes on the lower unit. 

IIRC, the service manual says anodes can be reused if 75% remains.  I believe the old ones were better than 75% but new ones are 100%.  Cheap insurance and the prepackaged maintenance kit from Suzuki includes the anodes. 

Two other sometimes neglected components that are susceptible to corrosion are the thermostat and the pop it water pressure relief valve.   I'm replacing the thermostat and cleaning and inspecting the pop it valve.  

[caveman]

Would one be better to tilt the motor out of the water even if the bracket remains in the saltwater while all of the anodes are above the waterline or leave the lower unit in the water?

I used to tilt mine up, but now leave it down to keep the anodes in the water.  Our water here (Tampa Bay) has a very high salt content.  I'm asking because I don't know, not trying to argue.  Thanks.

[tule peak timber]

Have you ever noticed when they recover a flight recorder, or for that matter any other electronics that have been immersed in salt water, that they will keep them in the same ambient water until they can get to a lab, flush with deionized water and then blow dry immediately. The wet/dry cycle on metals is very destructive. 

I don't have much experience with outboards, but decades of experience with marine machinery; all oil coolers, water coolers, hydraulic coolers, etc., no matter what metal they were made of would eventually have dissimilar metals in a system and all required regular replacements of pencil, puck, pig anodes. Way cheaper to cycle out the anodes every 6 months than to lose an expensive engine part or the engine itself. Just part of the cost of doing business.

[SawyerTed]

I'm not sure there's ONE answer to parking a boat at a dock with the engine up or down.  

I was instructed years ago to park with the motor up.  Electrolysis was "a" reason given but so was reducing marine growth and waterline stains.  I've also been in marinas where an extra low tide would put the prop in the mud. 

Of the dozen plus outboards I've owned in 40 years, most all  have had external sacrificial anodes on the transom mount and on the shaft near the cavitation plate. 

My current Suzuki has one on the very bottom of the transom mount and it has bonding wires to the mount in addition to the bolts.  


Looking up at the bottom of the transom mount on the Suzuki.   The anode is the slotted plate.  You can see the bonding cable/wire. 

My little 30 hp Tohatsu has a little anode block on the lower side of the transom mount.

The Tohstsu anode on the transom mount.  

[SawyerTed]

Continuing the 300 hours service.   My main reason for starting this was water pump replacement.  

I pulled the lower unit and replaced the impeller, the base plate, gaskets and pump inner pump cup.  


The new impeller and base plate.   


The pump housing with the inner cup installed


This is the old base plate.   A close look shows the plate is scored.  Between impeller wear, inner cup wear and the base plate scoring, the water pump was losing its volume.  The telltale stream is back to normal volume.  


Everything was tested on the muffs.  The telltale stream was good.  

Changed the thermostat and checked the water pressure diverter valve. Neither showed any corrosion or problems.   

New fuel filter and water separator element installed.  

Pulled the lower unit anodes and the transom mount anode, wire brushed them and reinstalled them.  They are 75% or so.  They will be fine for another year.  

Splines on the drive shaft and shift shaft were  greased before reassembly.   Inspected the prop and greased the prop shaft before reassembly.  

Everything was tested and run long enough to allow the engine to warm up.  

Crankcase oil and gear case lube were changed about 20 hours ago.  Shift and throttle linkages were lubed and marine grease put in all zerks.

I believe she's ready mechanically for the summer.  Now she needs a good wash and bottom paint refreshed and of course a full tank of gasoline.  

[YellowHammer]

Maintenance keeps em running!  How did the other water pump look? Permanent set?    

[SawyerTed]

Yes permanent set to the old impeller.  The bottom plate was scored and the cup was scored.   It's only been replaced once in 4 years.  

There was a marked difference in how it peed before and after.   

The grease on the drive shaft splines that insert into the bottom of the power head was about gone.  I doubt it would have come apart very easy at the end of the summer.

My last motor lasted 21 years (for me) when I sold it with the boat in 2021.  Last I heard it's still running in Lake Ontario.  I would have taken it off shore on the day I sold it. 

Maintenance is important when you run 60 plus miles round trips off shore.  My life depends on it, literally.  That doesn't even consider the replacement cost for a new motor.  

Thankfully I have a family friend who used to be a Suzuki dealer.  He's a wealth of information but lived to far away to lend a hand. 

[Stephen1]

 I pulled out my little  9.9 Evinrude this spring, changed the plugs and gear case oil. Fire up on the 3rd pull, its getting old,28 years old now,  it was always the 1st pull. I am amazed that this little thing just keeps on running. I run regular mixed gas, with sea foam in the gas, but always run it out of gas every fall. 

[SawyerTed]

Saltwater boats seem to get bottom growth pretty fast on the NC coast.   My previous boat I used at Ocracoke and Portsmouth one 6 weeks period.   The growth on the unpainted gelcoat was considerable.  That was despite daily use at planing speeds and several heavy brushing.  

The impact on performance was about 25 to 30%.  The boat would normally run top speed about 45 mph, it would only reach 34 mph with the growth.  It took scraping and sanding to get rid of all the growth. 

I painted the bottom of that boat.  This boat I painted within months of owning it.  It was time for repainting.  

The first two photos are after sanding before painting.  

The second two are after painting.  

[SawyerTed]

Okay, I'll admit I overlooked the water separator filter in my maintenance.  

It became a problem last Monday.  The engine started surging between 75% to 100%.  Then eventually decided to run rough at 75% power.  

Got one of the maintenance guys to pick up a filter for me.  The store across the road from his house, where his wife works, carries the filters.  

Changed it out on Friday.  No love.  It ran better but still seemed to be missing on one cylinder.  

Turns out an outboard mechanic (a couple actually) come to Ocracoke to work a week or so each month.  He was here and met me at the dock this morning.  He had the problem diagnosed and fixed in a bout an hour.  That hour included 20 minutes to go blow the injectors out with compressed air. 

He showed me what to do should it happen again.  Apparently a clogged injector is common.  I looked up OEM injectors thinking a spare would be a good idea.  Hahaha $186 each for OEM.    A set of 4aftermarket injectors is $80–135.  

[caveman]

I found a guy a week or so ago who had the Dr. H software to plug into Honda outboards to read codes.  I suspected a bad O2 sensor, but decided to pay him to verify prior to throwing parts at a problem that did not seem to really be a problem.  The motor ran great, but after prolonged idling, an intermittent alarm would sound, which drove me out of my tree.

After plugging in and running it on the rabbit ears for over 1/2 hour, he confirmed my suspicion of a bad O2 sensor.  I ordered one and replaced it along with cleaning the idle air control filter dohicky with carb cleaner.

My old skiff that we bass fish out of had a trailer that needed a bit of love.  John and I moved the bunk boards and installed new lag bolts a few weekends ago.  Today, I bought two new wheels and tires for it and replaced one hub and purchased new bearings and a seal for the one I took off.  It was repacked and put into a box behind the seat.  I have at least four other trailers with axles with different style hubs that I don't have spares for.  If one of them goes out, I'll likely let the rough end drag and come to the house.

This old trailer is almost 40 years old, but it still does a good job and has put that boat into some impossible places.  Thank goodness for 4wd and aggressive tires, sometimes a chain and a little outboard power to get out of the lakes, pits, holes that we launched it in.

[YellowHammer]

I've had to blow out injectors, make sure you don't damage the filter screen.

Injectors are built for nearly a hundred thousand hours of life, and almost never fail, but clog a lot, and yes, new ones are expensive.  However, there are several companies (Google) that will take your injectors and clean and flow map them, to make sure they are back to factory specs, and most times replace the O rings and the screens, and they do it for about half to 1/3rd of the aftermarket injectors.  I've done it several times, normally during the winter off season.    

[Larry]

I've had good results using a straight dose of Sea Foam the last couple of years. Regular use and proper maintenance would be better, but poor folk have poor ways.

[barbender]

I'm with you there, Larry😊