Thermostat installed correctly?

[jfw432]

The thermostat seems fine but when I first start up the boat, the temperature overshoots massively. I'll shut it down when I notice the temperature problem and after a few minutes, it'll run fine the rest of the day. I didn't own it long last season but I don't remember it doing this before. Yesterday it hit 240?F before I realized it and the exhaust manifolds would sizzle water when I splashed them. The seemed hot but it didn't sizzle like the exhaust manifolds.

I'm assuming that water goes down into the water pump mounted on the front of the engine, flows through the engine, comes back out the top, and then goes into the exhaust manifolds.

Since I've been troubleshooting this engine for a little while, I have been cranking it out of the water. It's possible that the water in the engine isn't full and that's causing problems but I would think after 2-3 minutes of cruising, there would be enough water flow to fill the engine.

 

[Bondo]

Re: Thermostat installed correctly?

Ayuh,... I'd suspect the raw water pump Impeller is junk...
There should be water by-passing the T-stat at all times, going to the exhaust manifolds...

What kinda motor, marinized by Whom is that,..??

 

[jfw432]

Re: Thermostat installed correctly?

Ford 351 windsor motor marinized by Pleasurecraft.

I won't totally discard the fact that the raw water pump is junk but I also have a hard time believing it is since it'll work perfectly after that initial over temp. I blew air through all the hoses as well and they seem to be clear of debris.

 

[jfw432]

Re: Thermostat installed correctly?

I think the problem is I've been messing with things on the engine that drain the water out of the long hoses attached to the raw water pump. If I pour some water in that hose, it seems to prime the pump and it can maintain suction but when it's dry, there isn't enough pressure to bring water through the hoses.

 

[jfw432]

Re: Thermostat installed correctly?

In case anyone cares, I took the boat out again today. Since I didn't drain the hoses this time, everything worked like it's supposed to.

 

[cobraowner]

Re: Thermostat installed correctly?

I had a tstat stick due to corrosion and the temp would spike shortly after launch, a quick tap on the housing brought back to normal and a replacement solved the problem. The temp sender measures the water temp in the block. If the risers are hot you are not pushing enough water from the outdrive pump.