Hot temp on gauge or not?

My PO had replaced the speedo/fuel/temp gauge and ever since the temp is right on the "H" once it's warmed up. The fuel amount didn't read right on the last gauge but the temp worked and ran in the middle between "C" and "H" he said. I am not sure if I should try a different sending unit as they may be matched to the gauge? He ran it like that and I have as well it doesn't seem to be overheating as the radiator cap never blows out steam- he said it has never overheated on him. Once you come to a stop or idle the gauge drops back down off "H" but moves back up as you get going again. The dash is cherry (must have been replaced) and the gauge should be grounded well. Any thoughts?

thanks

 

mine did the same thing. what i ended up doing was replacing the radiator b/c it wouldnt hold more than 8lbs pressure and got a real guage from autometer. you also could check to see if your belts are tight. you might not be turning the waterpump at higher rpms.

 

Check to make sure the voltage reducer is still there if the guages have been replaced.

 

sounds like your sender and temp gauge do not match. you may want to try a resistor in line with the sender wire. you could install a variable resistor and adjust it until you get the range you want, then remove it, read it's resistance and replace it with a fixed resistor of the same value.

 

You can use a regular old meat thermometer (usually just a couple bucks at the grocery store) to find out for sure what your idle temp is. It's the kind that has a metal probe and large round dial, usually accurate from 0 deg to boiling temps.

 

OK some good ideas. I will check the belt tension. I like the variable resistor idea. Would I get one from radio shack? What does the voltage reducer look like and is it behind the dash by the gauge- I will also check my repair manuals? But first I will check the idle temp. I assume I should take the rad cap off let her idle for a bit while checking the temp. What temp should I expect at idle?

 

It should bump up to just a few degrees above your thermostat temp, then back down and stay fairly constant. Not sure what is stock on an F-head, but as an example my V6 opens at 184deg and then flip flops between the high 170s and 186deg or so.

If you really want to get fancy, sears has a digital multimeter for about $30 that reads temp. It is very fast reacting, and so you can actually see the thermostat open and close by watching the numbers. Handy for measuring a lot of other kinds of temp as well, since it is just a tiny little probe on the end of a wire that can be stuck just about anywhere. Plus you get a mulitmeter to boot.

I have used both the meat thermometer and the multimeter at one time or another, and they both should serve their purpose for what you are trying to do. If you do end up going the variable resistor route, make sure you take an accurate measurement when you set your new value.

 

Well it did just as you said it would jayhawkclint. I got a spare thermostat from the previous owner and it is a 160 degree stat. We took it for a nice little ride today and the temp gauge did it's usual runnning mostly on the "H" after warmup and then falling just below at the stop signs. When I got it back and it was nice and hot, I grabbed the candy thermometer, released the radiator cap pressure and dunked the thermometer in. It read right at 160 degrees. So tonight with it cold I started her up and put in the thermometer at idle. It took awhile as the temp gauge climbed up into the mid range and then above for the thermometer to read much. It then shot up to 160 and would run slightly higher 165 or so and then cycle back down to 160 while remaining pretty much constant as you said. The temp gauge was at the higher limit but not quite on the "H" as I would probably have to get her running down the road to move it up just that little but more. I think everything seems right and the sensor isn't matched to the gauge as suggested.