intermittent overheating!!

[scotty83]

I have been getting an intermittent alarm ever since I bought this boat earlier this summer and if I backed off the throttle to neutral it would go way. Couldn't figure out why until the past two trips out to the lake. My temp would get above 175 and the alarm would sound but then the temp would go back down to around 150 when I put it in neutral. Some days I wouldnt get any alarms the whole day. What was weird was that the voltage was also going down to about 12 volts at the same time, which led me to believe that the belt might be slipping or something. I looked at the belt and it seemed pretty tight. Got the boat home and took out the raw water pump to inspect the impeller to see if that was the problem and to my amazement it looked in great shape. I got to inspecting all the pulleys to see if something was seized and this is what I found.

The idler pulley bracket had a broken mounting bracket. Causing what the pulley to move and loose tension under load.

Has anyone come across this problem before? I leave for Afghanistan next week so I am not going to fix it until next spring. I'm just hoping this what is causing the problem.

[R&T Babich]

I think you found the problem.
If the drive belt loses tension, then the accessories - engine water pump, raw water pump & alternator would slow down or stop.
The voltage would go down to battery voltage, approx. 12.5v, and would go up again when the alternator is spinning to around 13.2-13.4 v for charging.

[scotty83]

Thanks for your input. That is what I was thinking. I just dont have enough time to get a new bracket before I leave. Hate that I have to put her to bed before I get it fixed but such is life.

[scotty83]

After further investigation I found this in the hose that comes from the water pump at the top of the motor to the exhaust. WTF! Anyone know what this can be? It sounded a bit like sea shells but highly unlikely.

[scotty83]

it came out of this hose.

[R&T Babich]

...Anyone know what this can be?...

Our engine has just an elbow at the bottom of the exhaust manifold for the hose from the engine water pump.
What does the other hose connect to?
Have no idea what that stuff is, but it looks like the water pump ground it up.
Is it maybe a fiberglass lining from something?

[scotty83]

Funny you ask about the hoses. I just today figured out why my drain setup is different. It has a 3-point manual drain system. So I only have to pull 3 plugs to drain the water for winterizing when out of the water or 4 blue plugs if still in the water. The other hose runs to the 3 point system.

[chpthril]

After further investigation I found this in the hose that comes from the water pump at the top of the motor to the exhaust. WTF! Anyone know what this can be? It sounded a bit like sea shells but highly unlikely.

Looks like maybe lime or rust scales. Can you pick them up with a magnet?

[scotty83]

The stuff I found in the hose may in fact metallic. I had to get some out of the shop vac but it was attracted to a magnet.