Yamaha 20hp cooling problem

[TownsendsFJR1300]

Well, there's a significant problem looking at your second pic..

There's the water tube (maybe 1" in diameter) that goes up from the LU to the powerhead. That tube, in picture #2 is OVAL, NOT ROUND. That alone is a large water leak. Clean the end of that tube up spotless and gently / carefully re-shape it back to round as best as possible

I see the seal in the WP housing along with that "oil".. I'm surprised that isn't damaged.

Where does that round, flat plate with the seal go?

Whats the LU oil look like? I suspect the "oil", if that's what it is, is coming down from the powerhead. It appears to mixed somewhat with water and a pretty thick consistency. Some serious cleaning of the mid-section, LU and where ever else needs to be done and see where that's coming from. You may very well end up cleaning, re-assembling and then pulling apart again to see where this goo is coming from..

BTW, that engine isn't shown in the parts fisch here, so your eyes are essential in spotting things..

[luddovitch]

Well, there's a significant problem looking at your second pic..

There's the water tube (maybe 1" in diameter) that goes up from the LU to the powerhead. That tube, in picture #2 is OVAL, NOT ROUND. That alone is a large water leak. Clean the end of that tube up spotless and gently / carefully re-shape it back to round as best as possible

I see the seal in the WP housing along with that "oil".. I'm surprised that isn't damaged.

Where does that round, flat plate with the seal go?

Whats the LU oil look like? I suspect the "oil", if that's what it is, is coming down from the powerhead. It appears to mixed somewhat with water and a pretty thick consistency. Some serious cleaning of the mid-section, LU and where ever else needs to be done and see where that's coming from. You may very well end up cleaning, re-assembling and then pulling apart again to see where this goo is coming from..

BTW, that engine isn't shown in the parts fisch here, so your eyes are essential in spotting things..

Oh okay, i'm gonna look at the water tube and try to see if I can reshape it.

The round plate is where the impeller goes (if you flip it around you see the impeller) :
13901951_10209982047773918_557358435_o.jpg

LU as in lower unit? I changed that oil some days ago and the old oil looked fine, no signs on water.

[cpostis]

Mine will suck water without water pump housing below waterline. Not good though as it would seem the impeller would spin dry for a few secs prior to priming. F150 btw

Thanks pstephens,
Just to let you know, I did run my SX150 in a tank w/water level below the pump, and after a bit, had water flow. This was just after work that included inspecting the pump (pump was changed last December, and found good).

A run last month, although no overheat problems, I just wasn't satisfied with the tell-tale stream. I pulled LU again and found the impellor good, but the housing deformed/melted. Look at the top of the pic. Replaced whole kit , and now have good strong stream.

I'll now always ensure before starting that the water pump housing is flooded (including when run in tank).

[TownsendsFJR1300]

Just an FYI, looking at the impeller in the cup isn't really helpful(un-less the impeller came apart-which does happen!)

What is best, is outside the cup and check to see if the impellers "arms" (not the right word), expands outwards and DOES NOT have a "bent" set... The cup should be smooth and not scarred.

Any gasket, o-ring, etc that is even slightly dubious, SHOULD be replaced.

As posted above, it doesn't take much to lose water pressure, thus, just install the entire kit... And that water tube is loosing a bunch of water on its own. Imagine your garden hose on, with an opening that large at the nozzle-not good..

And yes, LU is lower unit..

[luddovitch]

Now I've checked the water tube, and it's not oval and doesn't look damaged.
Pics:

13682529_10209999367606903_897644476_o.jpg

13838619_10209999367966912_1003587734_o.jpg

Before I cleaned all the grease of I took this photo, hard to see but Im guessing this is where it comes from, the exhaust tube (I think this is the exhaust tube):

13844288_10209999366486875_94795374_o.jpg

I started the engine again after the cleaning and it was little greasy on the waterpump again, but didn't see any on the exhaust tube.

I'm running the engine on 2% oil mixture, it says 1:100 on the side of the engine so maybe the oil mixture is a bit high? I'm also getting some blue smoke, not sure if it's more than normal. So the grease/oil could be from high oil mixture maybe.

I will order new impeller kit today, costs about 140usd here in sweden, pretty expensive, guess it's cheaper over seas but I want it home this week so what do you do..

[TownsendsFJR1300]

I guess it was angle of the picture, great that it's straight..

Hopefully the water pump will help. Did you notice any twisted "set" in the impeller when you had it apart?

[luddovitch]

I guess it was angle of the picture, great that it's straight..

Hopefully the water pump will help. Did you notice any twisted "set" in the impeller when you had it apart?

Yes, the wings on the impeller is a bit bent or twisted when it out of the cup, and I got to admit that I found some more gaskets that isn't 100%. So yes, hopefully the new water pump will help and I can get out on the water again...

[luddovitch]

New impeller kit installed, water stream is still more like a spray than a solid stream But a bit better at idle. Think I need to get it out on the water again and try.

[99yam40]

run a piece of heavy mono like weed wacker line or a piece of wire up the tell tail while running the motor to see if that will get the solid stream back to normal.
Or compressed air blown up there to move things around some

[luddovitch]

I've tried that, not with the engine running though.

Not sure what to do next. Im thinking there might be something blocking the water lines, somewhere else than under the exhaust cover and under the head. Maybe I should lift the engine from the rig to see If I could see something? Never done this before, is it difficult?

[TownsendsFJR1300]

Its pretty much certain your getting water up to the power head. I guess you can check again at the thermostat housing to verify.

As 99Yam posted, running the line whole its running and water flowing will help flush out any debris.

If that doesn't work, I'd pull one water line at a time, including the end (at the cowling) and make sure their all clear. There shouldn't be many lines to check.

Couple of thoughts, if you can find where the main pisser, water line, exits the engine, start there and check the water flow. If normal, move onto the next section, etc.

Is the engine over heating at all when underway (all RPM's?)

[luddovitch]

Its pretty much certain your getting water up to the power head. I guess you can check again at the thermostat housing to verify.

As 99Yam posted, running the line whole its running and water flowing will help flush out any debris.

If that doesn't work, I'd pull one water line at a time, including the end (at the cowling) and make sure their all clear. There shouldn't be many lines to check.

Couple of thoughts, if you can find where the main pisser, water line, exits the engine, start there and check the water flow. If normal, move onto the next section, etc.

Is the engine over heating at all when underway (all RPM's?)

What do you mean by pulling the water lines? Remove the head again and check the water lines there again?

When i've tried it in a barrel yesterday after the impeller replacement I ran the engine a while at maybe 50% throttle and with my hand on the head it felt pretty hot, almost burnt them. But at that time the water in the barrel had already got a bit warm. I have a thermal camera at my job I can use to see the exact temperature, what should it be at half speed?

[TownsendsFJR1300]

Don't pull the head, that's already been checked and is fine.

If the water in the tank is heating up that much, you need to keep adding water(for cooler water) to water test the engine.

Even, leaving it on the trailer, backed up to the boat ramp you should be able to put it on gear(strapped to the trailer) and run it up some.

An open water ride (if you trust it), even better. I'm assuming there's some sort of overheat temp sensor on the engine.

Re the hoses, start at the actual plastic pisser end, make sure its clear(you can see light thru it. Then check the hose that connects to that, continue on till you run out of hose..(I don't know your hose layout)..


*Probably won't help much but certainly can't hurt. Invest in some "Salt away" and run it thru the engine and let it sit. NOT likely but possible some salt got in the line. Even if it doesn't help your current issue, it will help dissolve all salt residue in the cooling system. It doesn't take much at all for a flush..

I did some research on it and even thou I flush regularly with water, the SA apparently does a bit more. I've been using it for about 6 months now but haven't been "inside" the engine.

[luddovitch]

I was going to test the engine out on open water today, but my boat laungh at my local lake is in such a bad shape that I do not want to risk my car getting stuck. So im stuck with the barrel.

I dont think I have any hoses for my water lines. The tell tail is just a hole from the engine block, what I can see anyways.

[TownsendsFJR1300]

It may very well.

The parts fisch available here doesn't go back that far so i have no pic's/fisch to refer to.

If the pisser unscrews from the block, I'd pull that inspect that and probably start the engine with water should there be crap stuck behind it in the block..

Point being, check EVERYTHING from the pisser back...

Good luck..