2007 Mercury Optimax 150 HP Heat Alarm problem

"My heat alarm (continuous

"My heat alarm (continuous beep) goes off after a few minutes of idling or motoring around (about 10 to 15 minutes usually). If I give the motor gas or jump on plane the alarm goes off. If I come off plane and idle or motor slowly it will usually start again. Plenty of water pressure out of the pee hole, and water is not hot to touch merely lukewarm. There is water coming out of another port on the back of the motor which I am not sure about (thought is was some kind of exhaust) and that water is quite a bit hotter. I have not replaced anything yet just looking for suggestions. It just started doing this on my last fishing trip this weekend. Thanks in advance for your help as I am new to the forum and this is my first Mercury."

"If you are just getting the h

"If you are just getting the heat alarm without it restricting your rpm's, the problem is most likely in the portion of the cooling system that cools the compressor and fuel rails (and feeds the tell-tale).

The Opti's cooling system kinda goes in two different directions when it hits the powerhead. One way as described above, the second (diversion) is over to cool the cylinders.

If you get an overheat detected at the cylinders the computer will restrict rpm's as well as sound the alarm.

The usual culprit when you just get the alarm is a small screen filter at the base of the powerhead. Water is fed to the rails/compresser by a small tube that has this little screen filter on it where it (plugs) into the powerhead. The screen is rather fine and prone to clogging. If I'm remembering correctly they sell for about 5 bucks, so not even worth playing around with and is the easiest/cheapest method of troubleshooting an overheat where only the alarm sounds..."

"Thanks Graham for the informa

"Thanks Graham for the information. I was wondering if this is the part that you are referring to: Part #8348084 at the following site:

http://www.crowleymarine.com/mercury_parts/11756/140.cfm

The two marine places that I called have no idea what I am talking about so I am just trying to decipher myself."

"Chris, yes, on that diagram i

"Chris, yes, on that diagram it's #8 (Strainer - didn't remember the name that Merc called it). It's a little fine mesh filter to keep crud out of the compressor/rails..."