another thermostat question

for the first time in a long time my car was running hot while sitting in traffic. the motor is a new rebuild, so it isn't a plugged up motor, I replaced the radiator because the last one had a small leak (the radiator is a huge aluminum piece) so it isn't that, I have a duel electric fan that is working. I checked the thermostat (a 180 degree) in a pot of water and it opened at 180. im guessing my water pump is bad, but it shows no signs of wear. I will probably replace it with a TA high performance pump just to be sure

so here is my question, my fans are controlled by my MSD atomic fuel injection handheld computer. I can control when each fan turns on, with the 180 thermostat, at what temp should I have them come on? before the thermostat opens? or after?

 

Have you checked the timing and how new is the motor? When my motor was fresh, it ran hot for the first 200-ish miles then all of a sudden she went normal and stops at the thermostat temp.

You can see if the water pump is working by leaving the coolant a little low, the radiator cap off, warming the motor up to thermostat temp and looking in the tank to see if water if flowing.

I also shoot my thermostat housing with an infrared gun to see if it is really hot or not. Gauges can be wrong.

As for the fans, there isn't much use turning on either until the thermostat opens as that water isn't circulating that much. I'd turn the first fan on at 180° to 185° and the second one at 195° to 200° and see what that does. I'd expect when it opens for the cool radiator water to keep the temp down unless it is really hot in traffic or under load. Fans don't do a lot while going down the road unless your grille is restricted/blocked.

 

Are your hoses new/good. Does the bottom one have that spring that wont let it collapse?

Is your gauge bad?

Fluid topped off? Correct fluid?

Just giving you more stuff to think about.

 

If your rings are still breaking in it will run hotter then it was before the rebuild .
Did you burp the radiator yet?
If the motor is not showing any signs of ping or knock then advance your timing by 2 to 3 degree's and note what if any change in temp takes place.

 

A lot of the added heat a rebuild motor runs at is due to friction of the vertical end of the rings at the gap riding on the cylinder walls and not being rounded over.

Once these ware down and ware unneeded light grooves in your cylinder walls then the temps drop down !

 

Are you saying the rebuild ran normal temps., then hotter all of a sudden, or the OLD build ran normal temps. and the new rebuild runs hotter?

 

I was wo during the same thing as mark. Did you put the new radiator in at the same time as the new motor, b4, or after.

Judt cause the radiator is aluminum doesn't mean it will cool correctly,

 

excellent questions guys, let me see if I can answer them.
the rebuild is about 2 years old. maybe 1,000 miles on it
I replaced the radiator after the rebuild and after I noticed it was running hot
I doubt it is gauges, I have 2 coolant gauges, 1 mechanical auto meter and my TBI handheld
the rings are older ive had the pistons/rings for 20 years, just the block is newer.
hoses are in good shape (upper and lower). ill check fluid level and "burp" it (forgot to do that)
the timing should be on (it is controlled by the fuel injection handheld)

 

One thing I never liked about Aluminum rad's that seems to never get talked about is how they expand and the restriction level they have goes up as they get hot!

 

Sometimes a hotter thermostat can make the engine run cooler. The theory is that the coolant stays in the engine longer, and brings more heat out to the radiator.

I run 195-degree thermos in my 67 and my 1980 G20 van, and the coolant temp rarely crosses 200 degrees...but I don't do much driving in bumper-to-bumper traffic and it's not too hot out here (now).