How to tel if boat will over heat in the water

[Serf27]

If its the same as the Cobras that housing has a rubber ring inside to hold the 'stat in the housing. Might want to replace that ring too if it hasn't been done in a long time. The standard stat was a 160* unit.

Thanks, I’ll order the gasket before I do this. That gasket slipped my mind.
Parts catalog does show a temp sensor on the intake manifold. The one I have looks like it has threads have the seize of oem.
maybe I can wire the old sensor to the new gauge.

 

[Redrig]

maybe I can wire the old sensor to the new gauge.

I did exactly that , to a new faria gauge. Works perfectly

 

[Serf27]

I did exactly that , to a new faria gauge. Works perfectly

Great. Hopefully it works for me. It should, the sensors look like they have the same top.

Is there any downside to running the boat out of water with muffs for an extended period of time? Like 30-45 minutes.

 

[Serf27]

Well finally got around to hooking up that temperature gauge.
I always get excited about the boat and make plans to finish it up and life takes over!

but it’s on there now.
The new gauge is wired up to the old sensor. Posted this info above, just an FYI.

Temp readings on the gauge were extremely high though. My temperature gun which I believe is pretty accurate said something else though.

The actual gauge read 129 before the boat was even ran. Once running it hit 173° in a few minutes and after about 15 minutes it was between 240° and 250°
I shut the boat off and started reading hoses with my temperature gun.
Large house going to Thermostat housing read 135°
Thermostat metal housing read 159°
Small hose on thermostat housing read 111°
small hoses from exhaust manifolds read 143°-149°
Actual temperature sensor read 125°.

All the readings on the actual engine are pretty normal right?(when using the temp gun)

I’m thinking the gauge doesn’t work or the old sensor does not like the new gauge. The wire on the old sensor is a lot thicker than the wiring for the new gauge.

Any ideas?

 

[Redrig]

The sender has to be the correct OHMs for whatever gauge you are using.

What gauge did you get ? there will be a scale of OHMs for it (Cold to Hot) the Faria gauge I used matched the sender that OMC / Ford originally used .

Find out what scale the gauge uses and get the sender that matches that. (start soaking the old sender in penetrating fluid now for easy removal)

 

[Serf27]

The sender has to be the correct OHMs for whatever gauge you are using.

What gauge did you get ? there will be a scale of OHMs for it (Cold to Hot) the Faria gauge I used matched the sender that OMC / Ford originally used .

Find out what scale the gauge uses and get the sender that matches that. (start soaking the old sender in penetrating fluid now for easy removal)

I got this cheap one from Amazon.
HOTSYSTEM Universal Water Temp Gauge Temperature Meter Electronic Blue Digital LED DC12V 2inches 52mm for Car Automotive(Fahrenheit) https://www.amazon.com/dp/B008FXJS9...abc_QT7WRHW2FN2EY753YYE7?_encoding=UTF8&psc=1

I think it will be easier to find a gauge that works with the sender than to try a sender that fits the engine, don’t you?

here are some faira gauges I found. How do they look?
FARIA BEEDE 13004 Coral Water Temperature Gauge (100-250°F) - 2, Black https://www.amazon.com/dp/B000FOW4QE/ref=cm_sw_r_cp_api_glt_fabc_9REVZ48RXB9VGD6TC5ZJ
Faria Chesapeake SS Instruments - Water Temp Gauge (100-250) https://www.amazon.com/dp/B0000AZ7ZR/ref=cm_sw_r_cp_api_glt_fabc_SH5C98QMJ9H9AZTTVB3Y

 

[Serf27]

I also found this adapter that goes in between 2 hoses and it can probably house the sensor that came with the gauge, if I can’t find the correct gauge to work.
Dewhel Aluminum Black Water Temp Meter Temperature Gauge Joint Pipe Radiator Sensor Adaptor Clamps 38mm https://www.amazon.com/dp/B018FY12CW/ref=cm_sw_r_cp_api_glt_fabc_CS41RV76KNQMC75MMSEV

 

[Redrig]

Me personally , I would be leery of that gauge right off the bat. A nice Faria or marine one is just a couple bucks more. I'm willing to bet that digital gauge was bad right out of the box.

I cant comment on that adapter thing that goes on the hose , seems unnecessary to me . Just get a good marine gauge and appropriate sender and be done with it .

 

[Serf27]

Me personally , I would be leery of that gauge right off the bat. A nice Faria or marine one is just a couple bucks more. I'm willing to bet that digital gauge was bad right out of the box.

I cant comment on that adapter thing that goes on the hose , seems unnecessary to me . Just get a good marine gauge and appropriate sender and be done with it .

Any comments on the faira gauges I linked up above? Or could you point me in the direction of one that will work with my old sensor please.
thanks.

 

[Redrig]

I know that the original sender that OMC put on my ford was the "standard" scale of OHMs that most gauges used. I know that on newer stuff the different manufacturers use different scales.

Does anyone know if the Chevy OMC engines used the same senders ? I honestly dont know. But I would assume so , according to the chart below from Faria it looks like all the american marine senders use the same scale .

@Scott Danforth @kenny nunez .

Those 2 gents know alot more about this stuff than I.

here is the scale below for Faria.




One way to confirm and ensure the sender is good , do you have a multimeter with an OHMs setting ? If so , go see what the reading is on your engine while it is cold . If that reading is around 450 OHMs , you should just be able to buy a new Faria/ telexflex , etc gauge and use your old sender.

 

[Scott Danforth]

your gauges should be 240-33 ohm from 0% to full scale on your gauge (standard)

you then have to pair a 240-33 ohm sender with the right gauge (100-250F ) for example

same goes with oil pressure. you must have the correct 240-33 ohm sender to match your gauge. are you reading 0 to 60 psi, or 0-100 psi, or 0-150 psi (the gauge sender calibration is done in the sender to match performance)

some fuel gauges are 0-90 ohm from 0% to full gauge

 

[Serf27]

I measured the ohms but maybe I did it wrong. I put a probe on the sensor where the wire goes and the other probe on the engine where the sensor is screwed in. I didn’t get any readings.

 

[Serf27]

Bringing this thread back to life.

I did order a Faria gauge, but the temperature marking did not match my original gauge, so I didn’t use it.
With the use of adapters, I used a sunpro gauge with sensor similar to this one.
It may be the same gauge, I am not sure.

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The gauge has 3 prongs.
IGN/12V
Ground
Sensor signal

With the ground wired up, the gauge stays at 100°F. When I remove the ground, the gauge starts working….
Is this normal? No need for a ground wire? Maybe the sensor grounds itself on the engine when it’s screwed in?


I let the boat idle for 30 minutes and and temperature reached 150°F on the gauge.
Does this sound accurate?
The water coming out of the exhaust was warm and I was able to hold my hand against the flowing water, it wasn’t hot.
This was with water muffs on the drive and water hose water.

The cooling hoses on the engine read these temperatures with a thermometer gun.

Sensor/adapter-88°F
Small hose to thermostat housing-87°F
Medium sized hose to thermo hosuing-79°
Large coolant hose-92°
Exhaust manifold-94°
Intake manifold right by the sensor-94°
Thermostat housing-87°

Do these temperatures look right and look like they are equivalent to what the gauge was reading?
These temperatures look a lot cooler than the readings I took last year, in a post above.
I’ve added a photo showing the readings on each parts.
Thanks

 

[tpenfield]

It does not sound normal about removing the ground wire. Perhaps the ground wire is not actually a ground. Check it with your multimeter for 0 volts and low impedance to a known ground.

150˚ at idle may be fine, but the real test will be in the water under load. Running an engine on land proves very little, if anything.

Take you boat out for a ride and bring the IR temp gun to see what the various reading are after you have taken the boat up on plane for a while, etc.

 

[Renken2000Classic]

Best to just plan a like day with family and
Hope for the best? ... I’ve never taken the boat out. It needed so much work. Had to start making lists of what I was working on with it because I’d forget where I left off.

How do they feel about paddling back to the dock? Or waiting on a tow? Might not be the most conservative approach...

 

[Serf27]

It does not sound normal about removing the ground wire. Perhaps the ground wire is not actually a ground. Check it with your multimeter for 0 volts and low impedance to a known ground.

150˚ at idle may be fine, but the real test will be in the water under load. Running an engine on land proves very little, if anything.

Take you boat out for a ride and bring the IR temp gun to see what the various reading are after you have taken the boat up on plane for a while, etc.

What is ideal temperature when on the water? 170°-185°?

The ground is going to a ground block I added. The instructions call for chassis ground, but the ground block provides acceptable ground for other accessories.
Unless I need to run that ground wire directly to the engine…?

 

[Serf27]

How do they feel about paddling back to the dock? Or waiting on a tow? Might not be the most conservative approach...

HAHA. They probably wouldn’t like that.
Everything looks good on paper for the cooling system and the engine itself.
No over heating at idle.
New impeller and thermostat.
Good water flow when running on the muffs.
New plugs and dist cap/rotor.
150 psi on all cylinders.
Starts right up.
And throttle/gears are fine on land.

Just concerned about how the cooling system and engine will perform under load.