Johnson 225, temp send unit install ??

**Tightrig 12** · 01-19-2018, 03:07 PM

The 2.7 heads came with the boat when I purchased it along with two other complete built powerheads

**Tightrig 12** · 01-19-2018, 07:09 PM

Do you have a part number for the send unit you used ?
Thanks Bart

**phillnjack** · 01-19-2018, 08:44 PM

definitely better off with the gauge rather than daft over heat buzzers, when and if they work you are correct its too late, and you dont even know if they do work.
with a gauge you know exactly whats going on.
I put my sender in the already drilled and tapped hole, works perfect. dead easy to fit.. the threaded part of the sender also sends the temp, its not just the prop on the end.

**Tightrig 12** · 01-19-2018, 09:01 PM

Yes I agree...
I just ordered omc sending units ....i think I got the last 4 on eBay. Have to match 4 gauges to those send units.
Out of curiousity...where did you still and tap your send units ?

**mrichartz** · 01-19-2018, 09:02 PM

I don't have a part # for the sending unit came with the gauges...I think it is 1/8 npt...

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**Tightrig 12** · 01-19-2018, 09:03 PM

Sorry...my bad, I read your post wrong. The stock hole in the head .

**Tightrig 12** · 01-19-2018, 09:05 PM

Thanks ...i just ordered 4 OMC 172843 send units.

**powerabout** · 01-19-2018, 10:28 PM

Water pressure would be the next gauge i would have after the tacho then fuel pressure

**Tightrig 12** · 01-20-2018, 12:16 AM

I have new Levorsi water pres gauges at the helm and fuel pres gauges at the motors....holley blue pumps regulated to 4.5 psi
Should be in good shape after install of water temp gauges.

**phillnjack** · 01-20-2018, 11:27 AM

99.9% of temp senders on cars are perfect for the head on omc, they are the same thread.
you do NOT need to get a matching gauge for the sender, thats a myth... the sender just lets through more voltage (earth) as it gets hotter.
I have mercury , omc , smiths, jaeger, Durite and the cheapest nastiest Chinese gauges you could buy and all register the same with just a normal car sender.
its just a 1/8 npt.
the brass body and threads are enough to get the temp, and no putting it into water, you want the head temp not the water temp.
here is my little sender, very cheap and works perfect.
some people put dielectric grease on these, there realy is no need as the threaded part gets the temp too.

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**Tightrig 12** · 01-20-2018, 11:56 AM

Awesome Phil.....tks for the input
I do have 4 new OMC senders coming...they were $20 ea with free ship, only a few bucks more than a universal. Also just ordered 4 Sierra temp gauges and a quad pod for mounting.
Bart

**gfinch** · 01-21-2018, 09:47 PM

I used digital pyrometers with exposed tips. Tips directly into the water. Paid for it's self when the water pick up got a plastic bag over it. Guage has a red led that flashes if over threshold setting.

**Tightrig 12** · 01-21-2018, 10:37 PM

Sounds like a fail safe set up....
Gauges on the helm are pretty easy to ignore especially at high speeds....
These new temp gauges will be in full view just above steer wheel.
B

**phillnjack** · 01-22-2018, 07:45 PM

measuring the water is not the right thing to measure, these are not sealed circulation, its head temp your after... check head temps with infra red fin or normal way then compare.

personally I think outboards should come brand new with water temp gauges and the motor cut out if 20c deg over, then go into limp until cooled down.
my motor has the S.L.O.W feature, nut that will only come in at way too hot temp for my liking..

**Tightrig 12** · 01-22-2018, 09:19 PM

oem temp send units should measure head temp .being they are bottomed out in the head...realisticly doing the same thing as the too late buzzer but at least you can see it coming.