Fun Week End Yamaha Outboard

[wmgeorge]

Looks like I get to replace the water pump on my 40 Hp 4 Stroke Yamaha. I had a weekend planned on the lake. Now looks like a driveway project. Have the "official" Yamaha kit coming today, have the repair Manual and watched a couple You Tube videos so I think I am ready. I find out this is suppose to be a every 100 hours thing, and I don't think the previous owner did anything on the boat since 2008!

[Noitoen]

100 hours? Looks like inkjet printer cartridge kind of deal

[A.K. Boomer]

That's insane, Wonder if it's due to corrosion, them stilling for such long lengths of time half wet, sounds like your well overdue, So why the decision in the first place did the old one shell out?

[wmgeorge]

That's insane, Wonder if it's due to corrosion, them stilling for such long lengths of time half wet, sounds like your well overdue, So why the decision in the first place did the old one shell out?

Yes and I have it in my driveway ready to work on now.

[A.K. Boomer]

Was it still doing it's job or did the engine see excessive heat? any water in the gear bevels?

[CarlByrns]

100 hours sound about right- the pump sucks in all kinds of debris, no matter how the intakes are screened, on a fishing boat the motor gets tilted often enough that dry starts are a daily thing, or gets to sit dry for 4- 6 months. Looking back, I'd say all of our OMC outboards probably ran 100-200 hours between pump replacements.

[wmgeorge]

No or very very low water flow. Overheat alarm. My big problem now is getting the lower housing separated. All I have is WD40 and it sucks as a penetrating oil. Nobody in town of 60,000 people carries Kroil had to order from Amazon. Yes I have all the bolts removed, and tapping with a brass hammer so far has done nothing.

[RB211]

It's a wear item, normal maintenance. Be glad though, Yamaha is the best outboard you can buy for reliability.

[lynnl]

I no longer have a boat. My last was a 50 hp Mercury, which was a bitch to change ...particularly for someone only doing it once in a blue moon. I suspect it's the sort of thing that would come easier the more you do it. I seem to recall the OMC products were a little more mechanic-friendly with the water pump design. Maybe I'm mis-remembering.

In any event, given the option of: a) paddling back to the boat launch, or b) burning up the engine, or c) biting the bullet and spending an afternoon rolling around on the driveway, the decision process becomes pretty simple.

It would seem like the length of time the impeller has been in there would be a better gauge of when to change than total operating hours. ...more time for rubber to age and harden and deteriorate, etc.

[wmgeorge]

Thinking now this has never been apart, drilling and tapping a 1/4-20 access hole in leg. Aluminum and not to thick and I can measure to miss the shafts. Then I can spray the heck a lot of penetrating oil inside and let it soak as long as it takes.

[A.K. Boomer]

I hate boat motors due to all the corrosion - reminds me of wrenching on cars as a kid in michigan -- then add salt water boating, no thanks it would be a life of hell... I crack loose hundreds of fasteners weekly here - no penetrating oil -same size heads that they were designed with lol

[Jon Heron]

There is likely a set screw on the shift shaft you have to loosen.
Use plenty of grease when you put it back together, including in the cup and on the impeller to help it get broken in without losing a bunch of rubber and heating up the cup.
If its a trailer boat the corrosion shouldnt be too bad?

[A.K. Boomer]

In any event, given the option of: a) paddling back to the boat launch, or b) burning up the engine, or c) biting the bullet and spending an afternoon rolling around on the driveway, the decision process becomes pretty simple.

If the water intake screen is on the leading edge of the lower propeller unit the wisest decision could just be to "gun it" and get up to speed - water pump or not some systems can still pump water if you keep them moving like a shark has too to survive...

I think most intake screens are off the the side some but some are directly up-front maybe just for that purpose or to help the pump do it's job better when it's needed after all the highest full throttle demand for cooling would be the boat also getting up to speed, unless your towing something then your screwed... (without a pump)

I think the pitfall of having the screen directly up front is plugging, to some degree side screens would be a little more self cleaning that way...

[wmgeorge]

I have the service manual and no set screws, 4 bolts, plus bolt that holds trim tab on and all are out. Water pumps wear the intake screens were clean and I have them removed now.

[A.K. Boomer]

I think im seeing an alignment dowel in that diagram George, those gridlock as is but toss in a little corrosion and things really escalate --- and not knowing where it's at and prying in an opposing spot? might as well be welded...

check it all out let me know what you come up with...