Your Opinion On Overheating Cause
 

Some of you may have seen I've been trying to solve why my starboard motor overheats sometimes when idling. Never any problem above idle speed. Well this weekend I noticed when I'm idling in gear the temp gauge drops to zero. Take it out of gear and it immediately goes back to normal 150 degrees. Back in gear - drops to zero.

My cat is fitted with K-planes, water pick-ups and drain plugs. With the limited space on my transom the water intakes may be located closer to the lower units than normal. My theory is that turbulence from the prop at idle causes the water intake to "cavitate" and suck air when in gear. As the air enters the motor and hits the temp sender, the lack of water on the sending unit causes the temp to read lower than actual water temp and the gauge drops. If I keep it in gear too long the lack of water actually raises the motor temp while the gauge shows nothing, then when I put it in neutral the water cannot cool the block fast enough to stop the motor from rising to 180 or 190 degrees.

Does that sound possible or am I nuts???

Here's a picture of my transom layout.

Do you have a sea strainer on the
 

starboard motor? I would have someone put the boat in and out of gear and take a look in the strainer. I know on mine you can look through the plastic lid and if there is air you can see the bubbles. Normally when the motor is first started there is some air then it clears out. If you are getting that much air you will also hear it at the sea water pump. Weird problem. How is it when running the boat on plane? Have you double checked your guage to be sure it isn't a bad ground or sender? How is the water pressure? Let us know what you find and good luck.

this may sound crazy, but to test your theory, try spinning the props in...

Vette - Yeah, I have strainers on both motors. We had people with us yesterday when we noticed this new symptom so we didn't dig any deeper. We're going to check the strainer within the next couple of nights.

Sean - Hmmm... Not a bad idea.

I had them turning in before, but the boat really liked to lean outside in a turn. After cleaning my pants out a couple times I went to outward. It's worth a test though.

yeah...don't tell T2X I told you to turn 'em in :D :D

this is just at idle speed only, so I think you'll be safe :D :D :D