Why so hot??

[SPR1NK]

So the new engine my dad and i put together for his truck is running hot, crazy hot

220 cruising empty flat ground, saw 250 the other day goin up a slight hill and had to pull over to let her cool

Tried replacing the thermostat and water pump, no change still averages 220

Yesterday he took out the thermostat, now its averaging 180 degrees

What would make it run so hot?

 

[Selahdoor]

So the new engine my dad and i put together for his truck is running hot, crazy hot

220 cruising empty flat ground, saw 250 the other day goin up a slight hill and had to pull over to let her cool

Tried replacing the thermostat and water pump, no change still averages 220

Yesterday he took out the thermostat, now its averaging 180 degrees

What would make it run so hot?

You answered your own question. Wrong/bad thermostat.

You can buy a brand new tstat, and it can be bad. Or you may be buying the wrong tstat.

 

[dgr]

.....
You can buy a brand new tstat, and it can be bad. Or you may be buying the wrong tstat.

Or you could be buying a parts store thermostat which is not a motocraft thermostat.....

 

[SPR1NK]

Both thermostats have been motorcraft thermostats that we picked up at the dealership, they look exactly the same as the one thats in my truck and mine doesnt have a heat problem

I wouldnt let him buy a cheapo thermostat from the partshouse after the issues i had in my old 6.9 running a cheap thermostat

 

[SPR1NK]

Also when its running that hot if we hop out and use the no contact thermos on the rad, its usually 190ish at the inlet and 80-100 at the outlet, thermo says 220 when we point it at the block, changed gauges to make sure we didnt have a bad gauge and still says same temps

 

[dgr]

Sounds like you're doing everything correctly. Any chance the t stat is in backwards?

Where is the temp sensor? Mine is above the oil cooler and consistently reads 5 to 10 degrees above t stat opening temp

What about the radiator being plugged or the bottom hose collapsing? With the numbers you have, it sure seems like a water flow issue. I the think removing the stat eliminates the plugged rad... Hose spring in place?

 

[dgr]

One last idea. Air in the system

 

[saburai]

Both thermostats have been motorcraft thermostats that we picked up at the dealership, they look exactly the same as the one thats in my truck and mine doesnt have a heat problem

I wouldnt let him buy a cheapo thermostat from the partshouse after the issues i had in my old 6.9 running a cheap thermostat

Swap the thermostat. Then swap it back. That would give me a pretty definitive way of ruling out the thermostat.

 

[SPR1NK]

Temp sensor is where the factory temp sensor was, hoses arent collapsing, spring is in hose

What would swapping thermostat then swapping back tell me if there was already no change in temps when we swapped it out the first time

 

[SPR1NK]

How much of an effect on temps does timing have on these? It is super hard starting when cold after dad had someone else adjust the timing, maybe i need to get my timing meter on it again?

 

[The_Josh_Bear]

Also when its running that hot if we hop out and use the no contact thermos on the rad, its usually 190ish at the inlet and 80-100 at the outlet, thermo says 220 when we point it at the block, changed gauges to make sure we didnt have a bad gauge and still says same temps

That is a huge temp swing for a rad, is the radiator plugged up?

If that's not it then maybe the water pump is somehow not spinning or something. Do you have flow through the rad when you take the cap off and watch as the engine idles?

It's far easier to boil a tstat than to swap them all over the place...just verify it does its job and then you'll know for sure. Should open about 1/2" at 212* IIRC.

Good man running only motorcraft t-stats!

 

[The_Josh_Bear]

How much of an effect on temps does timing have on these? It is super hard starting when cold after dad had someone else adjust the timing, maybe i need to get my timing meter on it again?

Retarded timing makes them run hot but unloaded you'd really never notice.

 

[saburai]

That is a huge temp swing for a rad, is the radiator plugged up?

If that's not it then maybe the water pump is somehow not spinning or something. Do you have flow through the rad when you take the cap off and watch as the engine idles?

It's far easier to boil a tstat than to swap them all over the place...just verify it does its job and then you'll know for sure. Should open about 1/2" at 212* IIRC.

Good man running only motorcraft t-stats!

That would be easier. I guess I need to tie my thinking cap tighter. Or maybe loosen it

 

[Selahdoor]

That would be easier. I guess I need to tie my thinking cap tighter. Or maybe loosen it

I had to pry a bunch of tinfoil out of mine. I wonder who put that there?

 

[SPR1NK]

When we opened tye cap and started it all we could see was the antifreeze slowly rising up the filler neck until it started spilling out

It isnt factory rad, its a champion aluminum one if that matters