How hot should my car be running?
11-15-2017, 12:16 PM
#1
Thread Starter
Join Date: Oct 2016
Location: California
Posts: 49
How hot should my car be running?
Replaced the radiator this past weekend, eventually got the car started after it had been sitting for a couple months and was able to get a charge into the battery, then put a charger on it overnight so shouldn't be any issues there. Anyway, got it running, let it run for a bit, then drove it around the block a few times for 7-10 minutes or so. By the time I got it back into the driveway the temp gauge was at around 65-70% on the TEMP. The middle of EM being dead center on my gauge. Will try and get a picture when I get the car back next week from having the transmission rebuilt, but yeah how hot should the car be running? I had issues with the car getting really hot then found out there was a crack in my radiator, hence replacing it. Was hoping the new radiator would solve all the issues, but it may not have.
I also do NOT currently have a shroud on it. I was able to get my old shroud onto the new radiator after drilling some new holes in the sides to mount it, but because the new radiator has a lip at the top the shroud sits too low and hits the fan. I may be able to modify the shroud again and get it to fit, but that may be contributing to why it was a little hot. If I can't get it to properly fit, anyone know where I could get a shroud that fits my new radiator and doesn't hit the fan (radiator: http://www.speedcooling.com/1967-197...PS-Outlet.html)
If not a shroud issue, is it just the thermostat that may not be working properly? Or are there other possible issues I should be looking at?
I also do NOT currently have a shroud on it. I was able to get my old shroud onto the new radiator after drilling some new holes in the sides to mount it, but because the new radiator has a lip at the top the shroud sits too low and hits the fan. I may be able to modify the shroud again and get it to fit, but that may be contributing to why it was a little hot. If I can't get it to properly fit, anyone know where I could get a shroud that fits my new radiator and doesn't hit the fan (radiator: http://www.speedcooling.com/1967-197...PS-Outlet.html)
If not a shroud issue, is it just the thermostat that may not be working properly? Or are there other possible issues I should be looking at?
11-15-2017, 12:45 PM
#2
Moderator
Join Date: Dec 2005
Location: Hills of California
Posts: 5,208
I have found the temp gauge in my 66 to be quite accurate as it its always repeatable I can look at the gauge and estimate my true temperature quite accurately but this is only possible because I have cross checked with a modern temp gauge across its operating range....That stock temp gauge by its self is of little to no use especially since you'll have to consider its age and the probably that it may not be consistent or accurate.
If you aren't sure its working properly and you have not checked its position against true temp then you can not use it to make a confident estimation of temperature.
The easiest method would likley be the use of an IR temp gun. Measure the top radiator hose at the thermostat and at the radiator neck. Measure 2" away from the hose (you must be close and consistent in distance) IR temp guns will not work on shiny metals this is why you measure hose temp. The water in the top hose is return water and should be close to engine temp. Make several measurements along the top hose they should be consistent ...You can measure the Tstat housing as well does it agree close with the temp of the hose? If its not shiny metal it should be within a few degrees. (If all your measurements are close and repeatable then you are collecting good data and that is pretty close to your engine temp)
Do the same on the bottom rad hose...you'll probably have to lie on your back and measure it from under the car...mind the belts. The bottom hose is cool water that has had heat extracted from it by the radiator. The bigger the temp difference between top and bottom hose the better the radiator is working.
I checked mine in the summer its was about 102 outside and the top hose was like 190f and the bottom hose was like 155f. so in this case the cooling system had dumped 35f of heat.
If you aren't sure its working properly and you have not checked its position against true temp then you can not use it to make a confident estimation of temperature.
The easiest method would likley be the use of an IR temp gun. Measure the top radiator hose at the thermostat and at the radiator neck. Measure 2" away from the hose (you must be close and consistent in distance) IR temp guns will not work on shiny metals this is why you measure hose temp. The water in the top hose is return water and should be close to engine temp. Make several measurements along the top hose they should be consistent ...You can measure the Tstat housing as well does it agree close with the temp of the hose? If its not shiny metal it should be within a few degrees. (If all your measurements are close and repeatable then you are collecting good data and that is pretty close to your engine temp)
Do the same on the bottom rad hose...you'll probably have to lie on your back and measure it from under the car...mind the belts. The bottom hose is cool water that has had heat extracted from it by the radiator. The bigger the temp difference between top and bottom hose the better the radiator is working.
I checked mine in the summer its was about 102 outside and the top hose was like 190f and the bottom hose was like 155f. so in this case the cooling system had dumped 35f of heat.
