Temp/Thermostat

3rdtimer

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Joined
May 11, 2006
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3
I have a Volvo AQ 260A motor pushing a Volvo 290 outdrive. I have done a couple of 1-day trips with my boat, and I don't beleive I'm getting a temperature reading. The temp gauge needle is at the lowest point possible. My question is: Is it possible that my engine is running that cool? If not, I'm assuming I need to replace the temperature pickup on the engine and check the thermostat. Anyone have any good ideas about this procedure?<br /><br />Thank you in advance.
 

ron7000

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Jul 10, 2004
Messages
498
Re: Temp/Thermostat

yes it can run that cool,<br />most likely the thermostat but if the gauge never moves from the lowest point possible then it can be a bad gauge or broken or non-connected wire from the temp sender on the engine to the gauge. The temp sender is based on resistance and that's how the gauge knows what temp to display. High resistance is a cold temp and as temp increases the resistance lowers between the sender to engine ground.<br />what you can do to test the temp pickup (sender) on the engine is get a digital multimeter or any ohm-meter and measure the resistance from the post on the sender to ground on the engine block. As the engine runs and if it does warm up, you'll see the resistance measurement on your meter fall, meaning the engine is getting hot so there's a break or bad connection between the gauge and sender or the gauge is bad. To check the gauge, remove the wire going to the sender on the engine and touch the wire to ground, the temp gauge should jump all the way to hot. If it does, gauge is most likely good and either sender is bad or thermostat is bad.
 

3rdtimer

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May 11, 2006
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Re: Temp/Thermostat

Thank you Ron. Can I check the thermostat by pulling it and putting it in hot water to see if it opens up?
 

rdh2059

Seaman
Joined
May 16, 2005
Messages
55
Re: Temp/Thermostat

It should open up in water at around the setting that is typically stamped on the tstat. You need a fairly accurate thermometer to determine when the tstat should be opening. Most tstat's start opening up at 160degrees, but again you need to check what your specific tstat is designed to open at...<br /><br />Rick
 
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