Teleflex Temp Gauge Reads Low

[16sail]

1992 J100STLND

I just teleflex two gauges temperature gauges zbrackets the z-brackets under the head gasket bolts. I cleared off the paint under each sensor and made sure they were making solid contact. Even with that I find gauges the gauges barely budge off of cold.

Is this normal gauge this engine / gauge combo?

Is there a water jacket port haven't should use instead? I haven't been able to find it if it's there.

 

[16sail]

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1992 J100STLND

[Not sure why this got mangled when I posted. Here's an edited version.]

I just installed two teleflect temperature gauges using z-brackets under the head gasket bolts. I cleared off the paint under each sensor and made sure they were making solid contact. Even with that I find that the gauges barely budge off of cold.

Is this normal for this engine / gauge combo?

Is there a water jacket port I should use instead? I haven't been able to find it if it's there.

 

[Silvertip]

Re: Teleflex Temp Gauge Reads Low

Water temp and cylinder head temp gauges require different senders and temperatures will be different. If you have a head temp gauge you did it right.

 

[ScottGW]

Re: Teleflex Temp Gauge Reads Low

Water temp and cylinder head temp gauges require different senders and temperatures will be different. If you have a head temp gauge you did it right.

Are you sure about that? I just bought a sending unit that mounts to the head on a bracket and I was told it was for the water temp gauge by two OMC service techs and the company I bought it from, and in a thread I started here someon linked this http://www.iboats.com/bbboard/bbBoard.cgi?a=redirect;url=http://ww2.tflx.com/PDF/99625.pdf which says the same thing?

I am confused now

 

[Silvertip]

Re: Teleflex Temp Gauge Reads Low

OK - how does something that bolts to the head measure water temperature. That's why its called a cylinder head temperature gauge. A water temp sensor screws into the water jacket and measure the temperature of the water. The service techs are using the "generic" term temp gauge to cover both. If you had both types of gauges you would see they do not read the same. Here are the resistance readings for both types of senders (they are approximate as vendors play with those values).
Water Temp Sender: (100 - 250 degrees)
100 degrees = 450 ohms
175 degrees = 99 ohms
250 degrees = 29.6 ohms

Cylinder head temp sender (60 - 220 degrees)
60 degrees = 1195 ohms
140 degrees = 192 ohms
230 degrees = 46.5

 

[rickdb1boat]

Re: Teleflex Temp Gauge Reads Low

Geez, where can I buy a "Cylinder head Temp Gauge"?? You mean the one I have screwed into the head on my motor and hooked up to my temp gauge is the wrong one?

 

[Silvertip]

Re: Teleflex Temp Gauge Reads Low

I'll answer that question with another question. What do "you" think the sensor is measuring? Water temperature or cylinder head temperature? If you expect to read " true water" temperature you need a sender calibrated for the gauge that provides water temperature and it must be in contact with the water. The same holds true for cylinder head temperature. Look at it this way -- If yow stick an digital thermometer into a pan of water without it touching the pan, it will read water temperature. If you allow it to touch the bottom of the pan you now have contact temperature which is the temperature of the pan, not the water. Since you have combustion going on under the head temps can be higher than the water temp. It makes no difference what you measure as long as the sender is calibrated accordingly and the gauge corresponds to it. Use the wrong sender in any application and readings will be wrong. Again -- its simply a matter of what you want to measure.

 

[ScottGW]

Re: Teleflex Temp Gauge Reads Low

OK - how does something that bolts to the head measure water temperature. That's why its called a cylinder head temperature gauge. A water temp sensor screws into the water jacket and measure the temperature of the water. The service techs are using the "generic" term temp gauge to cover both. If you had both types of gauges you would see they do not read the same. Here are the resistance readings for both types of senders (they are approximate as vendors play with those values).
Water Temp Sender: (100 - 250 degrees)
100 degrees = 450 ohms
175 degrees = 99 ohms
250 degrees = 29.6 ohms

Cylinder head temp sender (60 - 220 degrees)
60 degrees = 1195 ohms
140 degrees = 192 ohms
230 degrees = 46.5

You did not click on the link I posted did you? The link is to the directions provided my Teleflex on how to install thier water temp gauge, and it list four ways to install thier sending unit, one of the ways is useing the Z bracket on the head, just like he did above. I have never seen a head temp gauge, if you have a source for one I would like to see it. And the temprature of the water, should be the same temp of the block seeing it is maintaining the temp in the first place. PLease read the teleflex directions, then tell us what you make of them, because I find it strange that the company that makes the gauge and sending units are wrong. I am not trying to argue, but seeing I have never seen a cylinder temp gauge and the teleflex directions are pretty clear, I want to make absolutely sure we are all on the same page.

 

[javsam2]

Re: Teleflex Temp Gauge Reads Low

sounds like bad thermostats.try taking them out and checking them.replace them if they are always stuck open.
javsam2

 

[wilde1j]

Re: Teleflex Temp Gauge Reads Low

There's no distinction made by Teleflex between metal temp and water temp. The same Teleflex sensor is either clamped against the head or screwed into a threaded well for the purpose of measuring cooling water temperature. It's not desirable, from a corrosion standpoint, to have the temp. sensor directly in the water stream, since crud buildup will quickly affect the reading.

 

[Silvertip]

Re: Teleflex Temp Gauge Reads Low

Yes I did look at the link you provided and it locked up my PC. Do a search for cylinder head temp gauge. Like water temp gauges they are all over the place and available in a variety of temperature ranges. They use thermocouples under a plug or under a bolt as a signal source. I can see this is going nowhere so I'll simply provide some basics. Temp sensors are thermisters or temperature sensitive resistors. They change resistance based on the temperature of the material or fluid they are in contact with. To provide a meaningful indication they must be matched to a gauge movement that is calibrated for the sender being used. If you look at the table of resistance values I provided you will see they vary considerably between senders. The key to this discussion is simply what's being measured. If Teleflex says their gauge is a water temp gauge and the sender is not actually in the water jacket, they are providing a "relative" or "engine" temperature reading and calling it water temp. The only way to prove what the true "engine" temperature is with a infrared gun or temp sticks. Most outboard temp gauges are now calibrated C-H (cold/hot) for the very reasons I've pointed out. If you are happy thinking its water temp - great. Be happy -- it might even be close. But in the end you are reading engine or head temp. You also need to know that identical senders vary all over the map for temperature vs resistance which makes a temp gauge about as accurate as a speedometer. I've calibrated too many gauges and measured too many senders to trust them. They provide a "relative" temperature at best regardless of the type you are using.

 

[ezeke]

Re: Teleflex Temp Gauge Reads Low

I listed the link because: (1) it directs you to the instruction manual which Teleflex includes with each of their "Water Temperature Guage"(s); and (2) it is sold here at iboats.

Try it this way: Copy the following link into your browser without the quotation marks.
"http://www.teleflexmarine.com/gauges-us/"

Then go to troubleshooting and scroll down to "Water Temperature Guage"

 

[ScottGW]

Re: Teleflex Temp Gauge Reads Low

I listed the link because: (1) it directs you to the instruction manual which Teleflex includes with each of their "Water Temperature Guage"(s); and (2) it is sold here at iboats.

Try it this way: Copy the following link into your browser without the quotation marks.
"http://www.teleflexmarine.com/gauges-us/"

Then go to troubleshooting and scroll down to "Water Temperature Guage"

I just got off the phone with the local OMC technition, I sent him a link to this thread, and we read ti together, and he said that water temp senders in the OMC outboards do not touch water, he explained that aluminum transfers heat so well that you get an accurate reading. He has been working on and selling engines for 40 years, so I think I will take his, and teleflexs' advise on this matter. He also suggest that the thread starter check his thermostat

 

[Silvertip]

Re: Teleflex Temp Gauge Reads Low

Did you read the note at the end of the Teleflex instructions that said engines will read differently and therefore readings are relative. "Any deviation from normal (for your engine) is a sign something is wrong". Then there is this information from my service manual. Thermomelt sticks (125 and 163 degrees) shoud be used for temp testing. Note they did not say water temp testing. At normal operating temps the 125 degree stick should melt. The 163 should not melt during normal operation. Here's proof of my point: "Thermomelt sticks should not be applied to the center of the cylinder head as this area is normally hotter". I don't care what the Teleflex guy said. Cylinder head temperatures rise a heck of a lot faster than water temperature and thats what burns holes in pistons. That is also why it is not a good idea to lug a two-stroke. Combustion temps rise rapidly. Now also consider this: If your gauge calibration starts at 120 (or even 100) degrees the gauge will not move far if normal cylinder head temp is somewhere between 123 and 163 -- especially if the engine is fitted with a thermostat that is set at about 140 degrees. So you see, the gauge may not read very high. If OMC says the center of the head is hotter, then the gauge cannot react fast enough if it is truely measuring water temp. To put you at ease, your installation is ok. But you are simply measuring engine temperature as it relates to the cylinder head temperature at that contact point on the head. If it were installed in the water jacket it would indeed be measuring water temperature. But again, the center of the head heats much quicker than the water around it so the reading is not meaningful at that moment. Efficiency of the cooling system will affect accuracy, as will the sender and gauge calibration. What you are after is to note idle and wide open throttle readings. In the future, any deviation from those readings, like Teleflex says, is an indication of trouble. To put you further at ease, my personal boat has a sender in the jacket (its a Teleflex) and the gauge is calibrated "C - H". I've calibrated the sender and the gauge and at normal operating temperature the gauge reads just above the cold tick mark. That's my reference and it wouldn't have made any difference if it read in the center of the gauge -- properly calibrated it would have been normal. I've exhausted my knowledge here. Have fun boating. Keep an eye on both the temp and water pressure gauges and you'll be fine.

 

[ScottGW]

Re: Teleflex Temp Gauge Reads Low

Did you read the note at the end of the Teleflex instructions that said engines will read differently and therefore readings are relative. "Any deviation from normal (for your engine) is a sign something is wrong". Then there is this information from my service manual. Thermomelt sticks (125 and 163 degrees) shoud be used for temp testing. Note they did not say water temp testing. At normal operating temps the 125 degree stick should melt. The 163 should not melt during normal operation. Here's proof of my point: "Thermomelt sticks should not be applied to the center of the cylinder head as this area is normally hotter". I don't care what the Teleflex guy said. Cylinder head temperatures rise a heck of a lot faster than water temperature and thats what burns holes in pistons. That is also why it is not a good idea to lug a two-stroke. Combustion temps rise rapidly. Now also consider this: If your gauge calibration starts at 120 (or even 100) degrees the gauge will not move far if normal cylinder head temp is somewhere between 123 and 163 -- especially if the engine is fitted with a thermostat that is set at about 140 degrees. So you see, the gauge may not read very high. If OMC says the center of the head is hotter, then the gauge cannot react fast enough if it is truely measuring water temp. To put you at ease, your installation is ok. But you are simply measuring engine temperature as it relates to the cylinder head temperature at that contact point on the head. If it were installed in the water jacket it would indeed be measuring water temperature. But again, the center of the head heats much quicker than the water around it so the reading is not meaningful at that moment. Efficiency of the cooling system will affect accuracy, as will the sender and gauge calibration. What you are after is to note idle and wide open throttle readings. In the future, any deviation from those readings, like Teleflex says, is an indication of trouble. To put you further at ease, my personal boat has a sender in the jacket (its a Teleflex) and the gauge is calibrated "C - H". I've calibrated the sender and the gauge and at normal operating temperature the gauge reads just above the cold tick mark. That's my reference and it wouldn't have made any difference if it read in the center of the gauge -- properly calibrated it would have been normal. I've exhausted my knowledge here. Have fun boating. Keep an eye on both the temp and water pressure gauges and you'll be fine.

That makes total sense, I just bought a pressure kit so I am hoping I have it all covered. My biggest fear is having my kids out there and I blow it up, she is an old girl but runs great (84 115) Thanks man, like I said before, I do not doubt you, but I have to be sure I have myself covered simply for the saftey of my family. So basicly between the two, and some common sense I should be in good shape?

 

[Silvertip]

Re: Teleflex Temp Gauge Reads Low

You are in good shape. Just make sure everyone that operates the vessel knows what the normal water pressure and temperature readings are. Above all, make them aware that when the gauges indicate a problem, the problem exists NOW. Many a perfectly good engine is ruined because an alarm horn sounds and the operator tries to make it back to the dock thinking I'll fix it later. By the way, installation of a water pressure gauge should be followed up with a new impeller. Then you know what the "normal" idle and wide open throttle pressure should be. Again, any deviation from the norm indicates a problem. Its not the actual reading that's important, its "what's normal" for your engine. Two identical engines can register different pressure readings.

 

[Mark42]

Re: Teleflex Temp Gauge Reads Low

Make sure you have the gauge and sending unit for outboard motors (reads low to high) and not inboard motors (reads 120* to 220* or so). If you have the inboard sensors and guages mounted as you have they will not start to read temps util the motor is really warm.

The outboard gauge reads low to high, and with the proper sending unit, it will read low or medium when warmed up. Not sure why they don't put temperature digits on the outboard gauge, but they don't. It starts to register around 90* or so and up.

The water pressure gauge is a good one to have too. I just installed one this spring and it is great to have. Reads around 3 PSI at 1000 rpm, and about 12 psi at 5000 rpm on my 40 hp.

In fact, just yesterday I took my parents out for an early evening cruise around the bay and was explaining what all the gauges do, Tach, Speedo, Temp, Water pressure, Volts, Fuel and how safe all this instumentation makes boating.... when I ran the prop into a sand bar because I wasn't paying attention to where I was going! LOL!

Edited to correct PSI and RPM for water pressure gauge.

 

[ScottGW]

Re: Teleflex Temp Gauge Reads Low

Good, I have a new impellar, new plugs, all fule and oil hoses, carb kit, plug wires and 120 psi per cylinder she pisses hard . the only problem I had I have now cured, she was buzzing "no oil", but it was due to not having clamps on the oil hose and she was sucking air, it would only buzz a little then as soon as I touched the oil bulb she would stop imedialty. She idles a little rough but I am going to seafom her per the FAQ instructions this week. I know the reading with be a "now" situation and no one, and I mean NO one drives but me. She was sitting for 5 or 6 years so this is why I am leary. Come to find out that she only has about 30 total hours! The last (and first owner) only took her out in lake mischigan and would just troll with the 6 horse kicker all the time (old couple) I called the number on the service sticker and got every bit of service info on her. SHe was serviced and maintained every year at Chaterton Marine in connecticuit so they had a detailed record from day one. She even got a brand new, updated VRO system.

Not bad for free8)