Heats up at 70+ mph

[T man]

Hey guys. My coolant system is relatively new but on the drive to work the cars thermostat starts to climb as I go over 70mph.

I burped the car yesterday and just went for a test drive but it's still happening. The car runs I believe 2500 rpm @ 75 in forth but I can run the same rpm around 50 or 55 in 3rd without and issue? Any ideas?

Not sure if it matters but The car has a transmission rebuild with a 3200 stall converter and runs low boost on a ford racing crate. Gears are 3.73

 

[driller]

Not sure if it matters but The car has a transmission rebuild with a 3200 stall converter and runs low boost on a ford racing crate. Gears are 3.73

It matters a lot.

Do you have a transmission cooler? Do you know if the converter is locking up? Is the cooling fan functioning properly?

 

[T man]

No tranny cooler. But I was under the assumption most of the heat produced by the converter would be when it's slipping during stop and go. In fourth at 70+ it's locked. I thought the heat would be the opposite?

 

[driller]

No tranny cooler with shorter gear equals more heat, regardless of converter. Are you certain the converter is locking?

Put a large stand-alone transmission cooler in and watch your engine temps be significantly lower.

 

[Roadboss]

Living in Florida you should do as suggested above and run a separate transmission cooler ( plate type). Also be sure your coolant system has been burped so that you have no air bubbles.

 

[T man]

Thanks guys I plan on buying one once I get paid. I use to be fine on the highway with the same setup.

I'm sure the converter is locking which I find weird because I thought more heat would be generated when it's slipping around town. There's also less airflow than when it's locked doing 70mph.

I might have burped it wrong.

Had both caps off and filled it cold. Covered the overflow tank and kept a cone with coolant in it on the crossover pipe and turned the car on. Reved it some and a lot of bubbles came out. I kept it there until it was warm and then capped the cross over.

I came back about 2hrs later and only uncovered the cross over and topped it off. I read drillers old post about turning the heat on while doing it but can't. The heat doesn't work

Did I mess that up?

 

[driller]

Keep cold-checking at the crossover until it requires no further topping off. IF the reservoir is low, top it off after topping off at the crossover. Important part is NOT to have reservoir open with crossover cap removed.

What's up with the heat not working? Does the coolant fan work as it should?

"Used to be fine" tells me something changed?