Proper operating temperature
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Junior User
Joined: Nov 2003
Posts: 82
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From: VA, USA
Proper operating temperature
This weekend I am installing an aftermarket temp gauge and am curious to what the proper operating temps are for a 1981 300-6.
Right now, the stock gauge will read H, but I'm pretty sure its not overheating. I just replaced the radiator and this is my next step.
Any help would be greatly appreciated!
Thanks
Neil
Right now, the stock gauge will read H, but I'm pretty sure its not overheating. I just replaced the radiator and this is my next step.
Any help would be greatly appreciated!
Thanks
Neil
Posting Guru
Joined: May 2003
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From: South Dakota
My '66 300 with factory temp gauge would run great in the 175* - 195* range any hotter and she would chatter. In the winter I could not get any heat at 170*. 'course the weather seals were shot so it took alot of heat to melt the snow.
Senior User
Joined: Sep 2003
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From: Houston TX
The stock gauge may still be good. Might be the sensor, or a grounding problem or something. Being as the usual stock t-stat is 195 degrees, I consider that the "normal" operating temp. But stats vary... Could be anything from 160-180-195, etc. I use the stock 195 stat. I don't like too cool of engine temps. Causes a decrease in efficiency, and also increased wear and contaminant buildup. I never use 160 stats. Thats too dang cold for a running engine...MK
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Junior User
Joined: Nov 2003
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From: VA, USA
Alright, let me put it this way, what is too hot? I was running a 180 tstat, now I've got a 195. I'm sure the gauge itself is fine, its the sender and the wire I'm worried about. I was going to replace the sender, but looking at the wire I figured its best to go with an aftermarket gauge. The wire is a little exposed at the connector and most of the plastic tubing is gone.
Also, after installing the radiator, while I was driving I look at the gauge and its at H, 3 seconds later I look again and its in the middle. I just don't see it cooling that much, that fast.
Also, after installing the radiator, while I was driving I look at the gauge and its at H, 3 seconds later I look again and its in the middle. I just don't see it cooling that much, that fast.
Elder User
Joined: Sep 2003
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HOT lights come on at 230. That's when a properly pressurized cooling system with a 50/50 mix of coolant and a 15 pound cap is about to start boiling.
Anything below that is fine, but I don't like my engines habitually running over 205 or so. To me, that indicates a problem of some kind.
190 - 195 is just fine.
Anything below that is fine, but I don't like my engines habitually running over 205 or so. To me, that indicates a problem of some kind.
190 - 195 is just fine.
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Junior User
Joined: Nov 2003
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From: VA, USA
Alright, so I couldn't wait till this weekend - kid in a candy store! So I installed it (in the dark even), and here's what happened. When I first started the truck, once it got up to 195 degrees, it dropped down to under 180. And that was idling in the yard. So I decided to take it for a drive for about 5-10 minutes. Never went over 195 and mostly stayed around 180. So far, so good. Once I got it home and let it idle it climbed up to 210, but if I put my foot on the gas, it went down to 195 and under. Is this normal? To me, it seems normal because at idle, its not pumping as much and therefore not cooling as well.
Other than that, no complaints. I'll drive it more this weekend to see how she does.
Thanks
Neil
Other than that, no complaints. I'll drive it more this weekend to see how she does.
Thanks
Neil
Senior User
Joined: Sep 2003
Posts: 497
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From: Houston TX
Yep, thats normal. At idle the water pump is pumping slowing and moving less water. Also, the fan is slower and moving less air. Quite a bit less , if no shroud. Kick up the throttle, and it's normal to see a pretty good gauge drop if you've been sitting still a while.
MK
MK
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Junior User
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From: VA, USA
Awesome! Its amazing how much I've learned working on this truck. 6 months ago I could change my oil and that was about the extent of it. Now all that is left is carb, shocks, tires and a bed. That is until something else breaks 
Thanks again
Neil
Thanks again
Neil
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Junior User
Joined: Nov 2003
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From: VA, USA
One more thing, I now have a big hole in my firewall that I need to fill in. My concern involves the wire going to the gauge. I'm sure a lot of you are familiar with this wire, it the metal coil type wire. My initial thoughts were to wrap the wire where it come through the firewall with electrical tape and seal up the hole with some type of gasket maker. And, if I can find something rigid enough, maybe put it ofer top of it. Is covering this wire going to interfere with the gauge any?
Thanks
Neil
Thanks
Neil
Elder User
Joined: Apr 2001
Posts: 772
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From: Glen Burnie Maryland
NOT COVERING (or protecting ) the tube (and it's a tube) and leaving it in a bare metal hole will cause the tube to rub against the metal and wear a hole in the tube. Then you lose the alcohol, or whatever it is in the tube and the gauge doesn't work. Take a piece of heater hose, split it and using wire ties, wrap the tube for about 8". Seal the whole thing up thru the firewall hole with Silicone (shouldn't be much clearance now). and you're done.
BTDT
Larry
BTDT
Larry
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Joined: Dec 2003
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From: Centerville, Iowa
My question concerns too low a operating temperature. My truck, if I'm lucky, will maybe get up to the N...but most of the time is even lower then that. Do I need some strategically placed cardboard or something? I would like it to stay relatively warm.
Elder User
Joined: Apr 2001
Posts: 772
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From: Glen Burnie Maryland
You may have a STUCK OPEN Thermostat. Real cheap fix (<$10.00)is a thermostat and gasket.
1st get the engine to operating temp with the radiator CAP OFF! Use a meat thermometer and check the temp of the coolant. If it's below 180 deg. or you can't get it that high, get a NEW 195 thermostat, remove the old and replace it with NEW. refill system and run and fill until you can't get any more coolant in and most all of the AIR OUT. Button it up after re-checking temp is 190-195.
Enjoy the HEAT!
1st get the engine to operating temp with the radiator CAP OFF! Use a meat thermometer and check the temp of the coolant. If it's below 180 deg. or you can't get it that high, get a NEW 195 thermostat, remove the old and replace it with NEW. refill system and run and fill until you can't get any more coolant in and most all of the AIR OUT. Button it up after re-checking temp is 190-195.
Enjoy the HEAT!
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Joined: Dec 2002
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From: Remsen, NY
Just a bad connection will make you read low. I was getting temperatures all over the place up to "N" in NORMAL until I cleaned up the connector on the temp sensor (back of the engine up under the manifolds). Now it goes right up to "N" and stays there nice. More resistance = bad connection = low reading. Less resistance = short to ground somewhere = really high reading.
But yes, thermostat is more likely the cause. The gauge connection is just something to keep in mind.
But yes, thermostat is more likely the cause. The gauge connection is just something to keep in mind.
Junior User
Joined: Mar 2002
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From: Home Town
HI
I know that if you change out a rad or any other coolant draining maint. and sometimes there can be an air pocket at or near the sender and that can cause odd temp readings but it clears up with a little bit of running, also you could need the block flushed out. I run a 160 stat but my engine mods prefer it. Some contaniments could build up but that's why we change the oil.
I know that if you change out a rad or any other coolant draining maint. and sometimes there can be an air pocket at or near the sender and that can cause odd temp readings but it clears up with a little bit of running, also you could need the block flushed out. I run a 160 stat but my engine mods prefer it. Some contaniments could build up but that's why we change the oil.