Installing Heat gauges and sensors on your outboard

If anyone is interested in installing heat sensors and gauges on their outboard send an e-mail to to me at [email protected], and I will send you the writeup with pictures.

My motivation for doing this project was that I’m concerned about the Honda overheat sensor detecting a overheat situation while I’m miles from homeport and immediately shutting down the engine. I want some warning before that happens. An extra bonus is that I can continuously monitor my engine heat, establish norms, and know when it’s time to change out the water pump or impeller before it gets bad enough to trigger the Honda overheat alarm.

sounds like a very good idea. i drive a truck & am so used to watching all my manual gauges. can't get used to the idea of waiting for a warning horn to tell me my $12,000. motor has just bit the dirt(water?). when the horn goes off I think you already have a beginning of damage to the powerhead. It will continually get worse in time. wish it came with manual gauges from fac.

Over many years I have found that monitoring water temperature and water pressure are very important for keeping your outboard in top running condition and preventing problems before they become damaging. Besides installing water temp guages as described in my initial message, most outboards these days seem to have an access port for testing water pressure. There is no reason you can't hook up to that and run a small tube to a pressure gauge on your console. That is my next project for my Honda 225.

Just be careful with material in sensors and nipples screwed into the block.
Most outboards use 'contact' temp sensor that is either put on a bracket outside and in contact with the head/block or installe in a pre-cast in the block.
Normal brass fittings/temp sensors in contact with aluminum and salt water may soon do more damage than good.

Roger that. The method I describe uses external heat sensors mounted externally on the manifold (or block) and secured with a bracket and a heat transfer epoxy - ArticSilver.

Nice work Chawkman. I would like to install a water pressure gauge to my 1999 Mercury 60hp 2stroke bigfoot motor. I believe one would use a fitting at the water tell tale port and run a 1/8" nylon hose to an appropriat mechanical gauge on the dash measuring 0 - 35psi assuming water pressure for this motor does not exceed 35psi. This i need to find out.
Secondly, one could also attach an electrical type pressure gauge to the tell tale port and use a matching gauge on the dash. Am i correct so far?....Please advise further........Tom

Not familiar with that motor. But, normally, I don't think a pressure tap or sensor mounted at the telltale will give an accurate reading of water pressure. I suspect there is a port somewhere on your water jacket that is designed for inserting a gauge and testing water pressure. If you can find that, then that would be your ideal point for installing the tap and hose. If not, consider tapping into the water jacket and installing a 1/8" NPT nipple. Should be pretty easy to do on that motor.

On and off I have been looking for a pressure sensor I could mount at the motor and simply run a signal wire to the gauge on the console, but I have not had any luck finding one. If you do, please let me know.