Temperature gauge on outboard?

deerhound

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I have seen a temperature gauge fitted to an inboard with the sender epoxied to the block, this gives owner some idea of where normal running is, the gauge has cold, normal, hot, can this be done on outboard or will temperatures under the hood be to great for such a gauge, has anyone done this? any advise please, JBD
 

rickdb1boat

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Re: Temperature gauge on outboard?

Yes, you can mount a temp gauge to an outboard. You would either use a "Z" bracket to secure the temp. sender up against the cylinder head or use the hole provided in the cylinder head, depending on the engine you have. Here's some more info. Head to Outboard Water Temp in the right column and then Look at the OTHER MAKES/MODELS at the bottom..

http://www.teleflexmarine.com/cgi-bin/frameset2.cgi?site=gauges&type=us&link2=1047 ] Click Here [/url]
 

Silvertip

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Re: Temperature gauge on outboard?

You will want to retain the standard sensor and wiring. A temp gauge is totally separate wiring. Switched +12V, ground, light, and sense (wire from new sender).
 

deerhound

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Re: Temperature gauge on outboard?

Thanks Rick, my engine is 1984 Evinrude 40hp BE40ELCR, I know there is a wire which I think is for warning horn which comes out top cylinder, does temperature guage get connected here? or maybe better just select position against block/head. Thank you JBD
 

KYHunter2

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Re: Temperature gauge on outboard?

Teleflex site , has alot of info . on this.

The sender , if theres not a place for it allready.

Can be bolted to the head , in a bracket as mentioned.

With the sender itself being, just shy of actually touching the head .

I like having both a temp. and pressure guage.

If I only had one , it would be the pressure guage.

Being I have the overheat sensor in the heads .

A loss in pressure when noticed , can be corrected before the engine gets too hot.

KYHunter
 

Silvertip

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Re: Temperature gauge on outboard?

The sender needs to contact the head or it will measure "air" temperature. Paint needs to be removed where it contacts the head. If there is an unused port into the water jacket it can be installed there as well.
 

rickdb1boat

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Re: Temperature gauge on outboard?

Look on the starboard side of the engine. There should be a "Blind" hole where a sensor would thread in. May have a plug in it...This is where it is on my 70 HP rude:

tstatcover2.jpg
 

deerhound

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Re: Temperature gauge on outboard?

Thank you for all information, looked at Teleflex web site and called UK teleflex dealer, they say senders come seperate from gauge and are thread sized 1/4", 3/8" and 1/2" on my engine there does not appear to be such a vacant hole as one shown in picture but on the actual starboard side of engine there are at least a couple of tapped holes vacant, I suppose any of these holes would suit if sender screws into them if not just make sure it is in contact with head? Can I assume that temperature range of these gauges will handle what it will encounter under the hood? thank you. JBD
 

Silvertip

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Re: Temperature gauge on outboard?

Here's the rub on temperatures. If you mount the sensor so its in contact with the head, you measure cylinder head temperature. If you mount it in a port in the water jacket so the sensor is actually touching water, you get water temperature. If you measure water temperature 140 - 160 degrees on most gauges that read 120 - 240, the gauge will barely move. And that includes many gauges that read Cold-Hot. Cylinder head temps will be hoter and will vary across the head so it all depends on where you mount it. Closer to the plug is hotter than out at the sides. Be sure you know what you are buying -- both in the gauge and the sender. Make sure the vendor knows its for an outboard and that you want either a water temp or cylinder head temp sensor. This always sparks various pro-con discussion so -- let the comments begin.
 

gss036

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Re: Temperature gauge on outboard?

I agree with Silvertip completely on this one. I just went through that w/a Merc 200hp. I used a new Teleflex Gauge and sender kit. The new sender was reading head temperature differently than the Mercury (hotter) so I had to go back to a new Merc sender to get the guage to read where it had before. I had a bad guage and thought it was the sender. The Telflex sender was reading hotter than the Mercury sender because of the way it fit in the recess in the head.
 

deerhound

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Re: Temperature gauge on outboard?

All noted everyone, even the UK teleflex dealer couldn't give me any info? refering me to an individual, I suppose therefore I require a Cylinder head sensor with gauge temp range to suit and move the sensor around the head to find best place, where would I start positioning the sensor would these vacant tapped holes on Starboard side of power block be good starting place? great subject, now that I am using boat I find I continually look around to see the tell tail running! but Evinrude 40hp runs a treat and I'm amazed how quite it is, some locals said that the 40 would not even get my boat onto the plane, they are lugging huge overpowered engines on their transoms with very little freeboard, my 40 has shown 37mph on the GPS at sea and may be slightly quicker on calm conditions, now to try and purchase correct sender for guage? any more advise please< JBD
 

Silvertip

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Re: Temperature gauge on outboard?

Out of curiosity I spent some time at an auto parts store looking at automotive temp senders. It doesn't matter that these are auto parts as they are brass and they are thermister (temperature sensitive resistors). Depending on their use, the resistance values are all over the map but in general, for outboards, you want a temp sensor that has a range of 30 - 250 ohms give or take a little. The sender and the gauge need to work in concert so I can't be of much help other than to experiment. If you can find an auto parts person that will take the time you can research the product specifications. It may take some time but the part is available. You will get the most meaningful cylinder head temp if the sender is closer to the spark plug. You may need to fashion a bracket that holds the sender in contact with the head. The bracket can mount under a cylinder head bolt. The picture shown above is a good spot since its near the thermostat and the upper spark plug. Here is mine on a Merc.

8b915656.jpg
 

deerhound

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Re: Temperature gauge on outboard?

Thank you Silvertip, I found a web site here in UK, called ASAP (I just put in search ASAP Marine) and got it, they provide pictures of sensors and I was surprised how many gauges and sensors there are, I would imagine as you say that I need a (matching pair) gauge and sensor within the temperature that it will encounter on my outboard, I note your comment on position of sensor, I'll post any developments, again many thanks, JBD
 

Silvertip

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Re: Temperature gauge on outboard?

For an outboard you want a temp gauge (and they are hard to find) that can read 60 - 200 degrees F. (Sorry - you can do the degrees "C" conversioin). The reasoning is that most gauges are calibrated at 100 - 120 degrees F on the low end. Normal outboard temps are not much above that point so the needle barely moves of the low end of the scale. The only way to trick it is with the sensor. For your application, I would look for one that has a lowest resistance of anything under 30 ohms. 25 would probably work to get the need up scale a bit. High end is not a problem but you'll want that to be 240 - 300 or so. Use a pan of water and an ohm meter and accurate thermometer to get actual temps. Don't let the sensor touch the pan. Just the water.
 

deerhound

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Re: Temperature gauge on outboard?

Just to update have tracked down a gauge here in UK, the make is Faria,is for outboards and covers temp 20-200c, comes complete with sender that bolts to cylinder head,ie one head stud is removed sender fitted and stud replaced, will advise how it operates, thanks again, JBD
 
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