Water temperature gauge / temp sensor installation

[Scottie]

I'm planning to add a temp gauge for each engine. I know there is an overheat warning built in if there's ever a problem, but I'd still like to see a gauge. I know @gmtech16450yz has done it, and perhaps there are others. My biggest question is about the temp sensor. What's the easiest way to install it? Is there an existing temp sensor I can piggyback off of? If this were a car/truck, I would just by the inline hose fittings for the radiator hose and install it there, but I haven't seen one of those fittings small enough to be used in the pisser lines, which would be really easy. Any thoughts or ideas?

 

[Scottie]

I looked up the "thermosensor" in the service manual. It looks like a standard temperature sender, and I suppose I could remove it, run some tests with a voltmeter and log the resistance at specific water temps, and then find an appropriate gauge and use that, but I'd rather not interfere with the stock system. So that leaves installing a new temperature sender. The easiest way I can think of is inline with the pisser hoses. Easy access, close to the helm for wire runs, cheap replaceable hoses if something somehow went bad (not sure how), etc. The fitting I need would be a brass tee branch, with 1/2" hose barbs, and a 1/8" female npt. That fitting does not apparently exist, outside of a custom order. However, a 1/2" female npt brass tee, 2x 1/2" hose barb to 1/2" male npt, and a 1/2" male npt to 1/8" female npt (for the temp sender), will make the proper fitting when assembled. So this is what I'll do, unless someone has a better idea, or a reason not to. This will be part of a big dash project during the off-season, so there will be plenty of pics and info. Planning to do a nice write-up on all of it. Wish me luck!

 

[buckbuck]

Not sure on your boat but that would require 4 sensors on mine. 2 engine and 2 exhaust.

 

[Scottie]

If I install the senders in the pisser lines, then I'll be getting a coolant temp for each engine basically. While maybe not exact, should be a good enough indicator of "engine temp". "Engine temp" is a pretty vague concept anyway. In the automotive world, 99% of your "engine temp" gauges are connected to temperature senders plugged into a water jacket or radiator hose line, so you're actually getting coolant temp.

 

[Scottie]

A write-up for temp gauge installation is here: https://jetboaters.net/threads/how-to-install-temperature-gauges-and-senders-for-engine-temps.23774/