I Posted a while back about my 95 f350 460 overheating. Lately I have been tinkering with it trying to get to the bottom of the problem. The problem is it heats up when idling if you put in neutral and rev it to about 2500 it will cool back down but slowly creep back up.yesterday I pulled thee radiator and had a shop clean it out they said it was at least half clogged so I thou that's it . Came back put It back I filled and let it run with cap off for about a hour . I had no problems then took off down the road got on hard and the temp shot up to about the m in normal and started coming back down . Got back and let the truck sit idling and the temp climbed up to about 212 before I revved it to cool it off . I'm Stuck the cap is a new16 lb I flushed the block the thermostat is a new 195 and I can watch the gauge go up to in between r and m then comes back to the o which buy a laser thermometer on the water neck is about 190 . The fan clutch comes on and sounds like a 747 so sorry for the long post but I'm stuck and don't really like throwing parts at something thanks

 

Try removing the thermostat and run without it and see if it helps

 

So, your gauge never gets out of the normal range? Because, that's normal.

 

200-210 is normal operating range. If it gets up over 220 that's when u gotta start worrying. Use a good guage to verify the actual temp. I had a 78 460 that would get up over 260 on the highway but run normal on the city streets. I replaced EVERYTHING with no luck. I finally took the heads off to find out the back half of the motors water jackets were clogged off with stop leak material. The back 4 cylinders had muddy brown water and the front four had clean, green antifreeze. Craziest thing I've ever seen. Well almost. Cleaned them out real good, and it ran 200-210 even hauling heavy loads.

Sometimes the thermostat trick helps if it flows slowly, but it can also hurt. The thermostats job is to stop flow to allow the antifreeze time to cool properly in the radiator. If it flows to fast it won't be able to displace the heat enough.

 

Guess I'm going to try taking out the thermostat. Idling in gear this morning it got to 220 before I revved it to cool it off . Almost makes me think it is a air flow problem ifthe hood is open it never heats up past about 195. But It has a shroud and all the rubber pieces are in place aroun the radiator. The only other thing is the 95 powerstroke I had way back had holes in the bumper I've wondered if that would work

 

I too would try removing tstat and see what happens. You may have to put it back in in the winter if you want a decent heater.

 

Let us know if that helps

 

Sorry it took so long to answer ended up taking the pulley off the pump. I found that I had a loose bearing so I replaced it. As it stands right now just idling with a/c on slowly just got to the r in normal when I put it in gear it climbed on up slowly so it is tolerable ,just can't leave it in gear idling in traffic for a long amount of time on a hot summer day. Still haven't gotten the thermostat out may try that later but at the moment I can live with what I have .

 

its not an airflow problem if your shroud is in tact and your radiator fins are not caked or destroyed. the "added airflow" or increased ability to bleed off heat via leaving the hood open is just enough to make the slight difference it needs to stay within temp.


if your radiator was truly 1/2 filled with gunk, then other parts of your engine are filled with gunk also. howd you flush the block?


can also confirm that your radiator isn't still filled with crud....its not easy to flush anything in the cooling system effectively.

 

your t-stat only restricts flow at tab bit, it will not stop the motor from over heating. the only function it preforms is, when it hits 195 it opens, after that it is the rad fan and flow that has anything to do with the temp, unless it is bad, (i.e. if it wants to run at 220 it will, the t-stat has nothing to do with that)

 

We are trying to figure out if the tstat is bad.ie by removing it to see if its not opening when it should. That would mean a faulty tstat

 

If th T-stat is stuck shut it will overheat quickly and will keep getting hotter until a hose or gasket pops. Like I said before, the sole purpose of a Tstat is to stop flow so the antifreeze has time to cool off in the radiator. The cooling system works by two main steps, coolant flow and heat transfer. If either of these is restricted, the motor will over heat. The more they are restricted, the more it will over heat.

 

Clutch fan is bad pretty common on this vintage ford truck

 

I'm still lost on this one. From what he's described his truck isn't overheating. It's acting completely normal. Even in his first topic about this he described perfectly normal operating conditions.

When I bought my truck the water pump impeller was completely rusted away. The only flow the coolant got was from convection; with the hot water rising to the top, and out the thermostat then to the radiator. I drove it like this for two months before I replaced everything in the coolant system. It would routinely go past the H on the gauge. That is overheating. The only thing that kept my motor from seizing was the cold weather in October, and November last year. Now that I've replaced everything the gauge never goes past the M in NORMAL.

 

No it has not completely overheated I have always stopped it before it got there . About the a in normal is as high as I have been willing to go which by a laser thermometer is 220 . I can watch the gauge and see when the thermostat opens was going to take it out because it was suggested. When I flushed the motor only used water so it probably wouldn't hurt to do some type of chemical flush . One thing that hurts the truck is it sat for a year or two only getting drove to pull a trailer here and there