Getting Warm On Highway

[LarryJoe]

So I just recently finished rebuilding both my bottom end and head. Everythings been running great except on the highway my temp gauge will start to raise, usually to 3/4 the way full. But as soon as I get off the highway it'll drop back down to normal and never gets hot while idling until today. I used a composite headgasket and ARP headstuds. I lubed all of them with the supplied lube, hand tightened the studs into the block, then torqued them in 3 steps. 45,60,95. I rechecked the studs today and all of them started moving at about 72ft/lbs so I retightened all back to 95. Would the fact that all of them were down about 23ft/lbs cause my warming up issue? And why did they lose so much torque?

 

[JacksonAuto]

Sounds like a lack of airflow getting to the radiator.

I used to have an older Camaro which had a front bumper that didn't have any gill openings. At low speeds the electric fans would supply enough air to cool the radiator. At higher speeds, there was an air dam under the nose to "scoop" air up and direct it through the radiator. One time I removed the air dam and as soon as I drove over 40mph or so the engine would overheat. I put the air dam back on and it went away.

 

[LarryJoe]

Well it never did this before the rebuild. Retorquing didn't help. Evoscan is showing like 244 degrees on the highway and 222 at idle.

 

[jjw205]

Well it never did this before the rebuild. Retorquing didn't help. Evoscan is showing like 244 degrees on the highway and 222 at idle.

Are you looking at the correct logged temperature? IIRC, there are 2 different temp readings in EvoScan, one is "Coolant Temp Scaled" and the other is just "Coolant Temp". The description in the corner tells which one to use for which ECU.

 

[luv2rallye]

Did you burp any air from the cooling system? To do it take off the radiator cap, gently squeeze the lower radiator hose, put the palm of your hand over the filler hole, release the hose, remove your hand, repeat.

Have new radiator cap and 50/50 coolant mix?

 

[kamikazeredneck]

I would lean to agree JacksonMachine's answer. Even though it didn't happen before many factors can affect the cooling system. Could any debris have gotten into the cooling jackets while doing the studs and head? If anything got into the system this could also cause the issues you are describing. Even a little RTV blocking a mm or two in front of a cooling jacket will cause a block in the cooling system and cause overheating at higher speeds. I would make sure there isn't any debris in the radiator or a small restriction in air flow or fluid flow of the cooling system. Is there any more problems you're having with overheating?

 

[luv2rallye]

Did you change to aftermarket fans that now don't have shrouds around them to help pull in air? Many have said the original factory fans with their shrouds move air way better than aftermarket without shrouds.