Older ProMax adding temp sender(s) to top of heads? Suggestions?

[W2F a V-King]

96 225 PM

Suggestions for drilling and taping top of heads for temperature senders?

Thinking I want one in the top of each head with dual gauges....overkill?

Which senders to use?

Is there something better to use?

[myron]

I run this setup with Autometer gauges, I can tell right away if one bank has a blockage or something not right.

[90 5.0]

All my promax’s came with an npt plug in the head already, I’ve only had to drill and tap fishing motor heads.

Anyway super simple 1/8” npt tap, drill the hole behind the thermostat, in the flat spot that’s there for it.

I like the auto meter electric water temp gauge kit.

[W2F a V-King]

This is my first PM, and as far as I know these are PM heads. Are 18789-C3 PM heads?
That's the casting number in them.

[tux974]

18789-C3 are the correct heads for a 225PM and the same as a 245/260, 38cc’s
Yes, drill behind the stat and use a short stem sender. You need a sender to correspond with the temp gauge you are using.
Keep in mind that temp will be approximately 30* different (cooler) when using a wet sender.

[Cervelo777]

A sender and guage for each head might be over kill, but I run two gauges, and like Myron mentioned it it gives you reassurance that both sides of the motor are performing equally. I have a glow shift digital gauge for right side and Speedhut digital on the left side, both read with in a degree of each other.

[W2F a V-King]

These look correct for the gauges and senders? Cheap enough for sure.

https://www.autometer.com/2-1-16-wat...ine-white.html

https://www.autometer.com/shallow-de...d-340-deg.html

[FORBESAUTO]

That should work. Just a heads up, from a previous thread a member had issues with the red needles fading. I’ve been using the marine carbon fiber auto meter gauges with silver needles and love them. I too, like some of the others run a gauge for each head, its nice knowing the temps of both heads to see that stats are working as should and plus can see any other issues that could arise.

[tux974]

Senders on both head though it maybe be nice personally feel its overkill and it may make you worry a bit much if you notice they are not running exactly the same. The star head could show a bit higher hence the reason Mercury put hot horn there so it lets you know sooner then later if you are not watching temp climbing..... Some noisy O/S boats get a bright little red light parallel to horn mounted on the dash facing you....
Also agree with FORBES on the needle color and fade issues.

[FORBESAUTO]

I do it for more than hot temps, I want to make sure a stat ain’t got trash stuck in it and not allowing a side to heat up as should before blast off, especially in the cold months. If it don’t, of coarse I don’t home, I just know don’t go beatin on the ole girl until I get her home and get the issue resolved.

[W2F a V-King]

All good information, Thank you all.

I like the idea of monitoring both banks. It might be overkill, but it won't hurt. Also like the ability of seeing if both banks are warmed up enough to hit it.

For $150 or there about, it's Cheap Insurance for sure!

Appreciate it guys!!