i have a 79 toyo truck with a 400 chevy eng. and a turbo 350 trani. the axles are original and 589 gears. i cant keep it from overheating. any help i have two fans on it.  

thermostat can be stuck is the top hose full when you squeak, do you see flow when taking the radiator cap off  

BMAN187:
i have a 79 toyo truck with a 400 chevy eng. and a turbo 350 trani. the axles are original and 589 gears. i cant keep it from overheating. any help i have two fans on it.

This is simple, not enough radiator and fan. Many think that electric fans are engine driven replacement but they cannot begin to cool a big motor because they simple do not move enough air. You need to get a bigger radiator in there and a engine driven fan if you really want it to stay cool all the time otherwise is is going to cook when you are into it.  

ok thanks but i put a big one in and have an engine fan also. i had to cut out the frontend of the truck to fit this one. maybe the fan shroud is not rite i may need to get a better one or build one that will flow the air better  

How big is radiator and how thick is it and what type of engine driven fan are you using? (ie, clutch, fixed or flex fan and number of blades)  

could be the shrouds not right. be sure it's tight against the radiator and only about an inch of the fan blades are exposed in the back (engine side). if you're running a clutch fan, be sure the clutch is engaging......easy way to check, bring the engine up to temp, shut it down then try to move the fan by hand. it should be tight, whereas when the engines cold, it will spin fairly easily.  

Also how many core is your radiator, and how big in diameter is your fan? I had same problem with my CJ, and just going up in size of fan made the differance. Also how much clearance between fan blade and schroud makes a big differance, to much gap alot of the air escapes instead of being pulled across engine.  

Air across engine has very little impact on cooling. Air through radiator core is what makes it happen.  

SnoMan:
Air across engine has very little impact on cooling. Air through radiator core is what makes it happen.

True, sorry about that. Should have been sleeping instead of on the computer. Was called out on a job at the docks last night around 10:30 welded until 6:00 this morning. My eyes was starting to cross, haha. At some point last night I think I may have been flashed, eyes burned all day.  

ok i think it is the shroud my fan is engine driven and it seems to not be  pulling air. if i let the truck sit the truck starts to run hot get goin and it will cool down. the fan has 8 blades and the radiator is a gibson the trans cooler is mounted to the front of the fan. this is hard for me because i have no time to really work on it and i am not that familiar with doin this. this is my first project truck. i was told that the shroud is bad its like not even having one should i make one or can i buy one i thought bought making it  out of lite alumanium. i work in ok but live in la so it is a challenge thanks for the input and i will try and use the info the best i can.  

well i have a 86K5 with a stupid 2 core rad and two electric fans and its stays at 1/4 on the gauge.  the fan is there to cool the engine when you sit at a light or just idling not when you move thats why fans have clutchs.  when you drive the radiator gets cooled by moving air which the cool fluid will flow back in to the engine.  so does this happen when your driving or at idle? if at idle prob the fan if at driving something is restricting flow, thermostat, radiator is pluged(very common) etc  

Have you checked the thermostat? Also check to make sure fan clutch is working. If your fan shroud is broken you need to repair or replace it. Also check the flow in the radiator make sure youdon't have a restriction.  

you can add an oil cooler also  

BMAN187:
i have a 79 toyo truck with a 400 chevy eng. and a turbo 350 trani. the axles are original and 589 gears. i cant keep it from overheating. any help i have two fans on it.

ya you are right overheating trucks are very dangerous sold it.
Used truck sales
Four wheeler for sale  

1986blazer:
well i have a 86K5 with a stupid 2 core rad and two electric fans and its stays at 1/4 on the gauge.  the fan is there to cool the engine when you sit at a light or just idling not when you move thats why fans have clutchs.  when you drive the radiator gets cooled by moving air which the cool fluid will flow back in to the engine.  so does this happen when your driving or at idle? if at idle prob the fan if at driving something is restricting flow, thermostat, radiator is pluged(very common) etc

You are lucky and likely not using A/C either. Clutch fans have clutches to prevent over cooling and limit noise. Ram air does not always do job and its effectiveness depend on speed, temperature and engine load. In practice, electric fans are no replacement for engine driven ones for serious cooling needs because they lack the HP to move a serious amount of air.