496 Mag HO running hot or is it?
07-24-2019 | 07:14 AM
#1
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496 Mag HO running hot or is it?
I have a 2005 496 Mag HO and it appears to be running hot at least according to the gauge. It runs about 185-190 while traveling done the lake and goes up to around 200-205 when coming off plane and back to idle then eases back to 185-190. I looked around on line and it appears that the ECM should be going into gaurdian mode if it is truly that hot, is that correct? If that is the case then could it just be a gauge issue? This is my first boat with a closed cooling system so I am open for any information. Thanks!
07-24-2019 | 11:23 AM
#3
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Sounds like the gauge or sender. 160-170 is normal, 180 is high, 190 will set off an audible alarm. I've had the alarm go off and the gauge was showing around 190. Also check (I don't know how) your alarm works.
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07-24-2019 | 02:16 PM
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I went by the lake today and lowered the boat into the water and fired it up and let it idle. The temp according to the gauge was 185 but when I checked the thermostat housing with an IR temp gun the temp was 150ish depending on where the laser was pointed. I believe that the sender pictured is the gauge sender and the brass of the sender read around 148 at idle. Please double check me and make sure I am measuring the temp in the correct location. 
07-25-2019 | 05:09 PM
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It has Livorsi gauges. I tried an Autometer sending unit on it today but the gauge read 30 degrees cooler than the IR temp gun so apparently Autometer uses a different resistance range. Does anyone know if Livorsi gauges are compatible with VDO sending units?
07-25-2019 | 05:14 PM
#7
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Unsure about auto meter, but the North American standard is 240 to 33 ohms (cold to hot or low pressure to high). There is a guy here with Gaffey gauges in his Fountain and the gauge pegs full scale max oil pressure. Replaced the sender and still pegs high. Measured the sender when cold and it measured 245 ohms, so his gauge is just bad, you may have similar issues
07-25-2019 | 09:31 PM
#8
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you have to match the sending unit to the gauge per ohms range.
The best way to see about the temp is to scan the engines from start up to fully warm and watch how and or the temp changes. You can compare all of that
You put the temp gun on the sensor for the reading. when testing the temps
The best way to see about the temp is to scan the engines from start up to fully warm and watch how and or the temp changes. You can compare all of that
You put the temp gun on the sensor for the reading. when testing the temps
