Snipe says I am overheating. So what's up?

[scooper77515]

After melting my oil lines and cooling lines last weekend, and having to sand down and repaint my exhaust due to burning all the paint off, we went out today and it ran fine, but....

Snipe called and I told him that after a wide open run and kill, and checking the plugs (see pics below) the overheat buzzer was going off.

All cooling lines were replaced this week, regulator was torn down and cleaned, and I now have the regulator cranked all the way down to keep water flowing all the time. Getting lots of good pee from the pee-hole. Top half of exhaust is cool to the touch, bottom half is warm, but I can put my hand on it for 3-5 seconds.

I am running 50:1 premix, and oil injection rich by 1 o'clock (not straight up, but advanced a bit rich), and yet it is buzzing like it is hot.

Take a look at plug pics. What kind of feedback can I get?

Plugs are two trips old, and only the rear plug is shown, as the front one was more rich than the rear.

First pic is after a 3 minute 4500 rpm run and lanyard pull, and second is 6500 for a minute or two and lanyard pull.

 

[scooper77515]

Am I overheating due to being lean?

 

[seadooya]

looks like Scoop, uyou got water inside cumbustion chamber...red/rust mark on plug.

 

[scooper77515]

Where would that come from?

What should i be looking at?

 

[Dr Honda]

possible bad O-ring in the head?
(just a guess)

But... those plugs don't look lean to me.

 

[scooper77515]

O-ring on head or at spark plug?

I will try to get those heads off today and take a look around, make sure all my lines are flowing freely.

 

[scooper77515]

I have cranked down the water regulator all the way bottomed out, so it will inject water even at high rpms. It runs well like this, and I was hoping to have better cooling at the exhaust to prevent another burnup.

Could this water somehow find it's way into the combustion chamber?

 

[6KJR]

It sounds to me like a cooling restriction. Ive heard of blocks filling up with sand before and not cooling. Could be any thing, something stuck in an inlet.. Could even be as far back as your nozzle where the pickup is..

Your plugs IMO are far from lean.

 

[scooper77515]

Too hot to mess with it today. Went into Houston to meet my folks for lunch for my birthday, and my truck's outside temperature gauge hit 100!!!

Got home, having a couple of wine coolers, and staying in the rest of the day. Got pretty sunburned yesterday, so need a cool dry day inside.

After work one day, I will pull the heads and check all the passages, and blow them out with high pressure air and make sure air is going through everything clearly. Basically back-flush the entire system with air, and possibly water, if it comes to that.

I know it sounds like a water flow restriction, but the engine is right at one year old and I have a hard time believing that I have sucked up sand or something. Where we boat is pretty clean, but I guess we could have sucked up a lilly pad or something.

 

[6KJR]

Youd be surprised what you can get into there. I found a seed stuck in one of the 3 water catchers..

 

[scooper77515]

Anyone ever hook up a water temp gauge? I cannot hear the beeps and would be more comfy with an actual gauge.

 

[scooper77515]

OK, took the heads off and everything looks good. All the lines are blowing freely and I see very little corrosion in the head cover.

There was a slight resistance blowing into the heater hose that goes from the head into the exhaust pipe, but only for a second and then it splurted out the back and I was able to blow freely through it.

Do you think I blew out the restriction, or just left-over water from the last time it ran?

Pics of head and pistons.

 

[6KJR]

Hard to say. If all your lines are free (INCLUDING) the one I mentioned in the pump for the main cooling water in, you could try it again. The little jet might of had something stuck in it.

Have you replaced your buzzer? I read somewhere, that someone (weather true or not) said that after an overheat, to replace the temp sender because its probably toast. Maybe someone can verify that information?!

 

[scooper77515]

I tested the temp sensor and it seems to be working ok. I went ahead and cleaned the corrosion off of it so it would be in better contact with the water.

Today or tomorrow I will pull the boat out and run it on the hose and make sure all the water inlets in the jet are peeing.