over heater kinda????
 

ok so where do the heater box hoes go?? and is anyone running a bipass hoes?? when i am running down the road the truck temp goes from in a sec 180 to 220 and then back down the next sec and does it over and over again. but only going down the road not stop. i have a new cap and thomest and water pump and rad and spal 2700 cfm fan. please help!!!

Re: over heater kinda????
 

That fluctuation could either be the thermostat opening and closing, or the electric fan turning on and off.

Some questions though. What kind of radiator is it? Stock or aftermarket....Aluminum or steel/brass? And also what engine/trans/rear gears are you running? All of these could factor is to your truck running hotter than you would like (220 is a bit high, but not dangerous). Also, most electric fan switches are set to turn the fans on at 220 and shut them off at 180, swap to an adjustable and you can lower that quite a bit.

Re: over heater kinda????
 

ok the fan is on a switch. and iam runing a 327sbc and 350t stock rear end i think 411 gears. the rad is a stock replacement aluminum. i was thinking maybe because iam running a the heater hoes into the thermostat houseing and not into the intake. its cause a presser thing because its after the thermostat and not before. or because iam not running a bipass hoes.

Re: over heater kinda????
 

Is this a problem that has been constant since you've been driving the truck, or a new development?

The 4.11 gears and TH350 trans could be a bit of an issue, with the engine running a higher RPM on the highway it would be generating more heat.

You really should run some kind of "jumper" hose between the heater hose outlet on the water pump, and the intake inlet (I might have the direction reversed there). If that flow cycle is blocked it could be causing your overheating issue. I did that when I pulled the blown out heater out of my Camaro and have never had over heating issues with it (it's a built 350 with TH350 rear, but only 3.43 gears).

Re: over heater kinda????
 

One thing I would do is make sure all air is out of the cooling system. Loosen radiator cap while engine cool and bring the engine up to operating temp. Worth a try.
Bob