Yamaha 20hp cooling problem

[99yam40]

as I said before, try blowing compressed air up the TT while running to see if that will move things around so a solid stream can be reached again.

Small bits of scale flaking off of cooling passages or sediment picked up when running in shallow water can get in the way and cause tt to spray on my C40 from time to time.
usually running some weed wacker line up it while flowing water takes care of the problem.

I guess if that is all clear then maybe you are getting exhaust into the water stream.

[luddovitch]

Okay, now I have tried with compressed air and wire up the TT. At first I didn't see any different but after reving the engine a bit it improved a bit.

Here's a video of the TT as it is now, You cant see it in the vdeio but just up at the TT hole the water is solid for maybe 5mm:

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And with a bit of wire in the TT the stream almost looked perfect, but I guess the wire just blocks the water a bit:

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I really cant think that im getting exhaust into the water stream. I have a new cooling jacket + gaskets installed and a new head gasket.

[99yam40]

Running In a barrel like that there is a lot of exhaust bubbles/gases in there that the pump is picking up also. Not clean water, so that may make a difference.
You will see when running out on the water if there is a cooling problem still.
good luck, hope all is well now

[TownsendsFJR1300]

That looks 200% better easily! Really, it looks pretty close to normal..

At idle, second video, a little on the weak side,
but un-less it overheats, your good to go.

I wouldn't hesitate buying that engine with that stream...

+1 about the aerated water tank too, that's not helping any..

[luddovitch]

Ok, just made a run out on the water. I ran it at full speed for about 2.8 kilometers (about 1.7 miles I think) and the water from the tell tail wasn't too hot at all. Right after the full speed run I felt with my hand on the head and it was too hot to have my hand on it, but I dribbled some water on it and it didn't just turn into steam like it did before (Only the water that came on the spark plugs turned into steam). But should it be so cool so I can lay my hand on it?

Another question, should it be 1% or 2% oil mixture? Im running 2% know, maybe a bit more, and it smokes a bit. The engine is also very hard to start when cold, but I think thats because the gasoline is too old. When the engine has started once its really easy to start.

[TownsendsFJR1300]

The engines are designed to run cool, (check your thermostat spec's). Use in salt water with a hot engine will cook salt to the cooling passages real quick and close them up.

It wouldn't surprise me you could touch the engine while running. Once you turned it off and the water drains, you'll feel a rise in the block temp(normal) temporarily... IE, my F150's thermostat is 136-158 F fully open.

Re the mix, its usually a 50:1 for pre-mixing oil to gas.

If that gas is old, DUMP IT. Unless you prefer doing carb rebuilds or potentiality damaging a piston or cylinder...

Sounds to me like your good to go!

[luddovitch]

Well, it's aint over yet...

Today I dumped the old gas and I found out it had water in it so maybe thats way it was so hard to start. I also drained the carb and the fuel filter. I thought it would fire right up, but no. Not even with start fluid in the cylinders, it turns out I have no spark on both spark plugs.. Also checked them outside the engine but no and not with new spark plug either.

I also tried with the "off button" disconnected.

Im starting to give up on this engine..

[pstephens46]

How did you check plugs for no spark?

[luddovitch]

How did you check plugs for no spark?

Held them against the engine block to ground them and then pull the recoil.

[TownsendsFJR1300]

The engine ran one day, the next time out it quit?

When you drained the carbs, serviced the fuel filter, etc, did you possible un-plug something(wiring) and its not fully plugged back in? Something lost likely is not plugged in fully...

If those/that check out, check your ground wires (R&R, clean if necessary), don't just look. You can't see corrosion under a terminal in most cases.

[luddovitch]

Okay, now I have worked on the engine again and I tried with a drilling machine directly on the flywheel and I have a very weak spark on both plugs. I also noticed that this engine only has one ignition coil to both spark plugs instead of one for each spark plug.

[luddovitch]

Not sure what to do next. Is it possible to measure the coil and cdi with an multimeter?

[99yam40]

some good reading on troubleshooting the ignition system

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