i have a 351m in my 1989 f350. ever since i got it which is about 6months ago. wen i take her out she runs hot. i start her up go play around in the mudd and cruise and stuff and then about 10 - 15 mins later shes hot. i changed the thermostat to a 180 degree but still ran hot. i believe the water pump work because i have watched the water in the radiator being pumped. i rly want to get this fixed so i can ran her more than just 10 mintues if anyone can help i would greatly apperciate it! old thermostat had the guts taken out of it

 

351M, or 351W?
an 89 should have a 351W in it, unless someone got creative and swapped the older engine in it.

V belts, or serpentine belts?
it is possible it has the wrong water pump on it, and the pump is spinning backwards.
it is also possible that the radiator is plugged up and not cooling the coolant.

 

-Make sure the radiator is clean, inside and out.. run the hose through it back to front to wash out any crud between the cooling fins if you're playing in the mud a whole lot. Flush out the inside by running the hose through it as well.
-Check timing?
-Do you have a fan shroud?
-Is your fan clutch locking up when it should or is it a solid mount fan? Is the belt tight and not slipping?
-Try running it without a thermostat at all just to see, though sometimes this makes it worse as the water doesn't have time to cool down if there isn't anything slowing it down to hold it in the radiator.

 

Does the truck have intake or exhaust leaks? If it does it'll run hot. Right Paul?

 

it does have a 351m the engine was swapped. it does have a fan shroud but it looks to little.... how do u knw if the fan clutch is bad? thanks for all these suggestions!

 

does it have v belts or a surpentine belt?
if it have a serpentine belt with the 351M water pump, the pump may be turning in reverse.

 

im not sure but i think supentine belt

 

check direction of rotation of the water pump. you may be spinning it in reverse. i have seen it happen quite a few times when people put serpentine belts on engines designed to run V-belts.

 

ight i will deff check that thnx

 

Good catch Tom. I wonder if they make a serp water pump for 351M. I was going to say I don't think they make a serpentine setup for the 335 motors, but that's just a matter of swapping pulleys, right?

 

yea im not quite sure cuz i cant remember. im in iraq im tryin to get her all fixed up for wen i get home

 

even easier. just reverse the belt.
if the belt is driving the water pump from the bottom of the pulley, it will spin one way. reverse the belt to drive the pump from the top of the pulley, and it will spin the pump the other way.
if it is hard to think of it the way i explained it, take a beer can and poke a rod through it to use as an axle.. take a belt of some kind and spin the can with the belt on the bottom. pull the belt from left to right. notice the direction the can spins.
now put the belt on the top of the can. pull the belt from left to right again. you will now notice the can is spinning in the opposite direction.

 

Never though of that tom, but that definitely makes sense

 

it drove me crazy the first time i ran into an overheat problem with a serpentine belt vehicle. a guy towed on to the shop saying it was running hot. i opened the rad to pressure test it and everything was good. then i fired it up and saw no water flow. took the water pump out and it was good. put the pump back in and put the belt on the way i took it off, and it was hot again.
finally broke out the book, and saw the guy put the new belt on the wrong way. it cost him $150 for that oopsie.
ever since that day, i pay close attention to belt installation diagrams.
i wasted 5 hours diagnosing a problem that was nothing more than owner stupidity.