50hp yamaha 2str - not pumping water

[Nelly]

pulled the lower unit - and got to the impeller - everything looks ok, which makes me wonder why it won't pump water. Impeller blades show no visible damage, and are still fairly supple. gaskets look ok, and the entire water pump housing (which came off to get at the impeller) looks sound. I think I'm going to pull it apart and replace with parts from a water-pump kit. But I'm pretty surprised that there's no glaring reason why it isn't pumping. And I did check to make sure the pee-hole wasn't clogged.

Any thoughts?

[flynny]

Do you know how old the water pump is? I'm no expert on water pumps, all I know is that they should be replaced every 3 years or so - maybe more frequently if you're in muddy, sandy shallow water.

[DaleH]

Could be a blockage in the water UP-tube from the lower unit or in the powerhead itself.

I'd remove the L/U and snake the water tube that feeds the head. I had this once on a 6hp OB, scrubbed most of the calcified salt out and then made a mix of Salt-Away in a large drum and 'carefully' ran the OB in that mix, running to soak it in and then leaving it off, giving the solution time to break down the build-up. It did work, but took time. Blockages in the head are tougher to fix, if that p'head uses fixed deflectors.

Have you checked your thermostats and popitts too?

[DaleH]

Aso, did you confirm the integrity of the woodruff key or similar that locks the impeller onto the drive shaft??

[Nelly]

Yep - wodruff key looked fine, and the interior of the impeller showed no signs of slipping on the driveshaft.

I'm thinking that there is a blockage in that water-up tube as there was some mud caked on the inside of the tube right where it goes into the water pump housing. I'm going to pull the thermostat too, to see what kind of salt, muck, etc. is caked in there. I'm wondering what the best way to flush the powerhead would be - is it as simple as blasting some water from the garden hose right up the "water-up" tube? Can you reverse flush such a system, or does the thermostat prevent you from being able to push water in the reverse direction?

[DaleH]

Sounds like you're onto it. I use plumbing snakes. The t-stat is normally closed, which seals off some head jackets to allow the temps to stay elevated at idle and speeds under 2K, typically. A hose with a pressure nozzle, some lengths of long wire, and a flat-wire plumbing snake should do the trick, plys remove the t-stat and flush whatever way you can.

Good luck,

[Nelly]

pulled the thermostat last night, and there was plenty of crusty salt in there. Took it out, and blasted away with the hose in the opening, to the point where I had water draining both back down out of the "water-up" tube, as well as the other way, out the pee-hole.

Took the thermostat and tested it on the stove, and it opened right at 50 degrees celsius like it was supposed to. So after cleaning it up, it's going back into the motor. Because I've got the lower unit off, I'm going to change the water pump. Hopefully when I get it all back together it will really pump strong!

[DaleH]

For parts and schematics, click here (http://www.boats.net/parts/search/Yamaha/Outboard/parts.html), but shudda added this earlier ;) !

See sample image by posting into your browser - http://www.boats.net/_search/images/parts_yamaha/62/03/0190/0001.png

[fatkenny]

I had the same issue with my DF 140 earlier this season. Buccobruce used some medical knowledge to resolve.

Take about a 3 foot length of steel or other thin wire. Think coat hanger but much much thinner. While the engine is idling and the earmuffs are or (or you are in a big bucket), feed the wire back up the water discharge hole. There are some bends and kinks so you will have to work the wire around a little. Eventually, you should be able to get about 2 feet of wire in, and the blockage will become dislodged.

Your motor should then "make good urine." If that doesn't work, then I would start disassembling things.

[G-Man]

Good job Nelly!
You're getting pretty good at this boat thing.
Any regrets?
I remember your humble beginnings with questions about the registry.

You have a good time on the boat this year ... found it to be a complete pia .. or somewhere in between .. like most of us. ;)

[Nelly]

G-man - funny you ask. I have really learned a lot this year about the boat, most of it through some difficult lessons. Some days I have longed to just throw the kayak on the roof!!!!

I have had continuous fuel problems, related from hooking up an old interior tank that had well aged 87 octane sitting in it for quite some time. Pumped out the old stuff, hooked up a racor and thought I'd be good to go. But it turned out that there was gunk getting through the racor and messing up my carbs anyway. That has been an ongoing battle, although I have learned to break down and clean the carbs (some of which I already knew from working on a motorcycle), which has been a confidence builder. It seems that as the ethanol gas has sat in the tank all summer, it has continually eaten away at the varnish in the tank and pushed it through into the Racor, so I've gone through about 4 of those so far this season, and they seem to be filling more quickly with a rust-colored substance that really is loosening up now. Starting to wonder when it will stop!!!

Now I've got this water pumping issue - but it's all good, because now I've figured out how to drop the lower unit, change out a pump, and a thermostat, and flush the system via those access points. There's a tremendous amount of satisfaction in doing something for short money - knowing someone else would be charging you hundreds for.

Certainly there have been some blood boiling moments, and times when I have laughed at how I thought I was getting a "free" boat - no such thing!!!(#$119)

Looking back on it, I probably would've just replaced that old tank had I known just how much crap was in it, but now I feel like I need to make it work given the time/money/effort involved in getting it back on line.

But getting my daughter a sabiki full of mackerel this July, and taking my little 1yr old and the rest of the family out to the beach on his birthday on Labor Day weekend have been great moments. Hard to have regrets when thinking about those times, and the more like them that await in the future.

Hoping next season I can do more fishing, and less boat fixing.:brow