Outboard boat engine mechanics?

XJsavage

XJsavage

CounterCulture
Joined
Aug 15, 2009
Location
Lyle's Ford SC
Just wondering if there were any on here that may be fluent in outboard tiller style boat motors.
I have a early 2000s model Johnson seahorse 25 2 stroke that I run nearly every single weekend. Over the last 15 years, it's been stellar. I keep up with general maintenance and I reguarally take the boat on river runs year-round anywhere from 2-60 miles at a time. The estimated number of hours on this thing will make your head spin and most would swear this thing shouldn't even be running still.
I have a current issue I need some info on. While running last weekend i noticed that towards the last quarter mile of my journey the motor quit "pissing", as in, the water cooled engine is not being supplied or expelling water. In my front yard im doing test runs with supplied water with tge use of an ear contraption and no luck. Nothing coming out of the tube. Common sense is saying it's a water pump. Is there anything else I need to check? A prefilter that's easily accessible inside the foot that might be clogged? All boat mechanic shops nearby are closed today or else I'd call them. Any help that might get this fixed and put me out on the water is greatly greatly appreciated.
 
How often have you checked or replaced the pump impeller? It's probably worn out, especially if it gets silt or sand through the cooling system. Impellers usually only last a few hundred hours, or a lot less if you're running shallow and sandy.

You may still have a clog though, and I don't think there are filters on most engines because they would clog extremely fast. A lot of people use weedeater string to break up silt clogs. It's obviously a lot more involved to clear out if you've got silt packed in whatever hoses and water jackets in the engine.

Are you at all confident in being able to drop the lower unit yourself to replace the impeller? I've done it about twice to help friends so I'm no expert either. I don't even have a boat, but I did used to work for an engineering division of a major outboard manufacturer. I'm no stranger to friends with impeller failure.
 
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Fabrik8 said:
How often have you checked or replaced the pump impeller? It's probably worn out, especially if it gets silt or sand through the cooling system. Impellers usually only last a few hundred hours, or a lot less if you're running shallow and sandy.

You may still have a clog though, and I don't think there are filters on most engines because they would clog extremely fast. A lot of people use weedeater string to break up silt clogs. It's obviously a lot more involved to clear out if you've got silt packed in whatever hoses and water jackets in the engine.

Are you at all confident in being able to drop the lower unit yourself to replace the impeller? I've done it about twice to help friends so I'm no expert either. I don't even have a boat, but I did used to work for an engineering division of a major outboard manufacturer. I'm no stranger to friends with impeller failure.
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Thanks for the help. My confidence as far as dropping the lower unit... Never done it before, so there's that. :lol:

The impeller being worn out makes sense. In its years of service, AFAIK, it's the original. How it went from working/pumping to nothing has me curious. Certainly a possibility though.
I may play it safe and take it by the dealer. If it costs me $200 or so to fix it, it'll pay for itself in enjoyment first few trips out this spring. :D
 
Put it this way, you're way overdue for a new impeller. The impeller is some type of rubber, so it's forgiving of normal crap getting sucked in from the water column in an open-loop cooling system. If you have a clog, that would explain the pumping problem. If you have a clog and then the impeller runs dry, the impeller is going to destroy itself. It may have just chosen that time to lose all of the impeller vanes though, if they were brittle, aged, etc.

If you're curious about what's involved in dropping it, YouTube has a lot of videos. It's usually not that hard, there's a coolant tube that connects the pump housing to the engine (and various ways for that tube to attach, etc), and the shaft drive, and a shift linkage (and various ways for that to attach, etc). There's usually a few bolts or draw bolts to hold the lower unit in place to the rest of it, and the pump is usually at the top of the lower unit. So if you remove it, you're usually looking at the top of the pump housing. The impeller is keyed to the shaft drive.
 
Sounds like I have another project for tomorrow now. I'll atleast drop it and get familiar with the mechanics of it.
 
ddbarr4 said:
JR if you run into an issue give me a holler I've got a Johnson evinrude repair manual and I've done a few.
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Ah... Mr Barr. PM me your number when you get a chance. Long time no see and several new phones later. :D
 
Most boaters say to change the impeller every 2 years or so. Hard to believe yours has run so long. But the ones that run on a regular basis, tend to last longer. Guess they don't dry out as bad. Shouldn't be too hard a job on your 25, & parts are Cheap. The foot, also has gear oil in it, which should be checked occasionally. Hope your familiar with that.
 
It should be easy to R&R the water pump if the bolts that hold the lower unit and wp are not seized from 15 yrs of immersion. Take the wp apart and replace the gaskets and anything that looks worn along w the impeller. Might be hard to pry the impeller off after 15 yrs. go round and round prying w a screwdriver, maybe some penetrant. Clean and grease the driveshaft. Be sure to twist the fins on the impeller the same way as what's left of the original one and dishwashing soap helps to push them into the cup when assembling. Sealant might be on the wp bolts, if so clean them well and put sealant on them, Be sure to put plenty of waterproof grease on the lower unit bolt threads and they'll be easy to get out next time.
 
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