I have a 1980 C-30 with a raw water cooled Atomic 4. I have been attempting to get the engine temperature gauge to work. I noticed that there was no movement of the gauge so I replaced both the sending unit and the gauge. Still the gauge doesn't budge off the 100 degree mark. Today I disconnected the signal line at the gauge and connected it to my multimeter. I connected the other lead of the meter to ground at the gauge. I then started the engine and watched the resistance of the sending unit change from just over 700 ohms to around 190 ohms as the engine heated up. As I understand it, this is exaclty the predicted behavior of the sending unit. So, can anyone offer an explanation of why the temp gauge doesn't register? The sending unit and gauge are both new from Steward Warner and provided by a source that has always been reliable in the past. Any suggestions will be much appreciated. Baffled in Benicia Bob Boller
Engine temperature gauge mysteries
- Thread starter sailingdude
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check your thermo
could it be that a previous owner removed the thermostat? that would explain why you run cold. my atomic 4 operates between 140 and 160 degrees.
could it be that a previous owner removed the thermostat? that would explain why you run cold. my atomic 4 operates between 140 and 160 degrees.
Thermostat has not been removed
I recently had the thermostat out, cleaned it all up and tested it to ensure that it was opening at 140 degrees. Bob
I recently had the thermostat out, cleaned it all up and tested it to ensure that it was opening at 140 degrees. Bob
Temps
Bob, I had the same problem with mine. I pulled my thermostat cleaned it and check to make sure it opened in hot water (it was also only 2 years old). However, what was happening is that the thermostat APPEARED to be closing all the way after it had been heated up but indeed was not. It was allowing cooling water to pass prematurely and therefor never letting the engine get past warm, and never letting the temp gauge register over 120 (which on my gauge looks like it is not working). Don Moyer of Moyer Marine told me this was a common problem with the Oberdorfer OEM thermostat. I replace mine with a Volvo thermostat that only cost $30 and can be purchased at Boat US or West Marine it has a much better rep for quality and only cost less than a 3rd of the OEM thermostat. Moyer Marine actually list the Volvo thermostat for sale on his website now. Good Luck, Paul
Bob, I had the same problem with mine. I pulled my thermostat cleaned it and check to make sure it opened in hot water (it was also only 2 years old). However, what was happening is that the thermostat APPEARED to be closing all the way after it had been heated up but indeed was not. It was allowing cooling water to pass prematurely and therefor never letting the engine get past warm, and never letting the temp gauge register over 120 (which on my gauge looks like it is not working). Don Moyer of Moyer Marine told me this was a common problem with the Oberdorfer OEM thermostat. I replace mine with a Volvo thermostat that only cost $30 and can be purchased at Boat US or West Marine it has a much better rep for quality and only cost less than a 3rd of the OEM thermostat. Moyer Marine actually list the Volvo thermostat for sale on his website now. Good Luck, Paul
Troubleshooting guide
I found this link that has a page deicated to troubleshooting temp gage problems. http://www.teleflexmarine.com/Pdf/Instruments/TechCat3_1-Instruments-TECH%20REF.pdf
I found this link that has a page deicated to troubleshooting temp gage problems. http://www.teleflexmarine.com/Pdf/Instruments/TechCat3_1-Instruments-TECH%20REF.pdf
Trouble Shooting Guide - Take Two
Sorry, try this http://www.teleflexmarine.com/catalog.html Go to the Instrument Tech Ref. Page 22 of 23 D
Sorry, try this http://www.teleflexmarine.com/catalog.html Go to the Instrument Tech Ref. Page 22 of 23 D
power to gauge or bad gauge
Did you verify 12 vDC was feeding the new temperature gauge? Does the new gauge go lower than 100 Degrees farenheit and it is just staying in the 'middle'? Did you try the old temperature gauge to see if it moves? You could always try a cheap resistor from Radio-shack -- say a 100 ohm and see if connecting it between the new gauge and ground would cause the gauge to work. Albeit not a straight-line relationship, the minimum 190 ohms you encountered should result in a gauge reading of greater than 100 degrees farenheit (my M25XP diesel reads 137 ohms @ 150 degrees farenheit, albeit one of them are off by about 15 degrees F). Hope this helps...
Did you verify 12 vDC was feeding the new temperature gauge? Does the new gauge go lower than 100 Degrees farenheit and it is just staying in the 'middle'? Did you try the old temperature gauge to see if it moves? You could always try a cheap resistor from Radio-shack -- say a 100 ohm and see if connecting it between the new gauge and ground would cause the gauge to work. Albeit not a straight-line relationship, the minimum 190 ohms you encountered should result in a gauge reading of greater than 100 degrees farenheit (my M25XP diesel reads 137 ohms @ 150 degrees farenheit, albeit one of them are off by about 15 degrees F). Hope this helps...
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