Backup temperature gauge+sensor (digital)

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Ryanman

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I have a 92 Johnson GT200. Love the motor so far. As of now I have not deleted the VRO yet… I would like to set up a temperature gauge as a backup to the overheat alarm in the ignition using the blind hole on the head(or one on each head price dependent). I can’t find ANY digital gauges (1/8”NPT) with sending unit that don’t have a range of 100f to 300f. Anyone have any suggestions? Thanks!!

Ps: other posts to come regarding VRO delete and slower top speed on ranger 297v!
 
dingbat

dingbat

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Ryanman said:
I can’t find ANY digital gauges (1/8”NPT) with sending unit that don’t have a range of 100f to 300f. Anyone have any suggestions? Thanks!!

Ps: other posts to come regarding VRO delete and slower top speed on ranger 297v!
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Install a water pressure gauge instead.
Pressure gauges let’s me know I have a problem in the raw water cooling long before an overheat situation occurs.

Can actually see the thermostats looking and closing. Lets me monitor long term pressure, let’s me know when it’s time to change the impeller
 
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Crosbyman

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if you want temps... hook-in (Mc Giver) a BBQ wireless remote ... works on steaks :)

they alarm to when done.
 
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Ryanman

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dingbat said:
Install a water pressure gauge instead.
Pressure gauges let’s me know I have a problem in the raw water cooling long before an overheat situation occurs.

Can actually see the thermostats looking and closing. Lets me monitor long term pressure, let’s me know when it’s time to change the impeller
Click to expand...
Thanks for the advise 👍. My water pressure gauge is working fine (I think), I was hoping for a little added security. Or at least a fuzzy warm feeling when I look at the gauge!
 
dingbat

dingbat

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Ryanman said:
Thanks for the advise 👍. My water pressure gauge is working fine (I think), I was hoping for a little added security. Or at least a fuzzy warm feeling when I look at the gauge!
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Unlike auto and I/o that cools the block using a secondary water pump, an outboard runs a single loop through the heads and back overboard

The only way you can overheat is to loose water pressure which is why outboards come with pressure instead of temp gauges

Alarm the loss of water pressure at the moment that happens or wait for the overheat alarm to go off after the damage is done?
 
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Ryanman

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dingbat said:
Unlike auto and I/o that cools the block using a secondary water pump, an outboard runs a single loop through the heads and back overboard

The only way you can overheat is to loose water pressure which is why outboards come with pressure instead of temp gauges

Alarm the loss of water pressure at the moment that happens or wait for the overheat alarm to go off after the damage is done?
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Well, my only response would be that water loss is not the only way in which the heads can overheat? It could alert me if my temps rise because of my engine running a bit lean correct? Thank you!
 
dingbat

dingbat

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Ryanman said:
It could alert me if my temps rise because of my engine running a bit lean correct?
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Outboards don’t tolerate running lean whatsoever. Running an outboard with a lean condition for any length of time is a death sentence.
 
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Crosbyman

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Crosbyman

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agree.. I am just offering options for temperature alarming.

personnaly I have never had a temp. alarm in 60 years of boating.

noise smell and steam is usually enough to warn me.
 
ct1762@gmail.com

ct1762@gmail.com

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Crosbyman said:
agree.. I am just offering options for temperature alarming.

personnaly I have never had a temp. alarm in 60 years of boating.

noise smell and steam is usually enough to warn me.
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if you are in a clean fresh lake, no issues. if you are like me and boat in super weedy shallow saltwater, we get alarms all over the place! but the other way an outboard overheats is far more common than loss of water pressure: thermostats stuck closed. or almost as bad (for a longer period): stuck open and running stone cold. i agree and love both overheat alarm and a temp gauge. type in "outboard temperature gauge" you will see plenty that are properly marked, unlike automotive ones.
 
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72lightning

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I did the exact thing you are looking to do.
Perhaps you've already fitted something.
I have a 1999 130hp v4. Carburated. Still with VRO.
I too did not trust the normally open circuits on the factory fitted over temperature switches. Due to broken or accidentally disconnected wire rendering alert function useless.

I used a very cheap device (x2). 1 for each head. They cost about $10 each.
Digital display using a NTC temp sensor.
Epoxy and drilled brass thread blind bung into the 1/8 tapped holes adjacent to each thermostat housing.
Works well.
I set the display inbuilt alarms at 85degC.

I am however upgrading this system through our winter (in New Zealand).
New system is 8" sunlight readable display raspberry pi based with wifi comms to a cluster of senders in the power head.
Senders are...
2x head Temps.
Exhaust gas temp, this is the fastest way to read you have ANY issue with over heating (see scream and fly forums).
Water pressure

The cluster of instruments in the power head might also have each cylinder head temp reading from spark plug fitted NTC senders.
A means to measure oil delivery.
Being either. VRO pump oil side piston pulses. Or vacuum (negative pressure) in the oil line.

This project will cost approximately $400 nzd. Which is approx $200 usd.
Once completed I will post it on forums.
 
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