Really hot after shut off?

[83kid]

Hi,
So irecently replaced the heater core in my truck, and just before that the intake manifold gasket as it was leaking coolant.
So, now no coolant leaks.
But, Whenever i stop and shut the truck off, the temp with go up to around 210-215
Temp is 160-190 driving around town, perfectly normal
Why would it do this?

 

[DoubleDingo]

Maybe a tad low on coolant and when it's turned off the water settles and steam rises up the sending unit. Steam is hotter than boiling water. Just a thought.

 

[MadOgre]

You should do a good flush and see if it persists?

 

[Driver4r]

That's normal. When the engine is running the water pump is circulating the water throughout the block. And cooling it thrue the radiator. When you shut it off the cooling factor goes away and it's still water. So the heat will collect. Then when you start it back up you circulate and add the cooling factor.

 

[Georgeb]

2X what Driver4r said

 

[83kid]

That's normal. When the engine is running the water pump is circulating the water throughout the block. And cooling it thrue the radiator. When you shut it off the cooling factor goes away and it's still water. So the heat will collect. Then when you start it back up you circulate and add the cooling factor.

Just the issue i have with this, is before i did anything thatd affect the coolant, it would only hit around 200 or so off, and i didnt fill the coolant while running it since i did the heater core, so its probably a tad low im thinking

 

[350runner]

norm...

Sent from the dust in front of you!

 

[firebane]

Just the issue i have with this, is before i did anything thatd affect the coolant, it would only hit around 200 or so off, and i didnt fill the coolant while running it since i did the heater core, so its probably a tad low im thinking

Cooling system are a closed and pressurized system. When you change one component other areas can become weak or work properly.

When no swapped the radiator and thermostat in my truck the next thing I knew my heater core failed.

Once I change that I should be good but I have 2 heater hoses and a water pump which could give me grief.

 

[MadOgre]

Cooling system are a closed and pressurized system. When you change one component other areas can become weak or work properly.

When no swapped the radiator and thermostat in my truck the next thing I knew my heater core failed.

Once I change that I should be good but I have 2 heater hoses and a water pump which could give me grief.

Canadian Tire has those heater hoses for cheap. They come in a package with 5ft of both sizes.

 

[rich weyand]

The core of the engine (pistons, bores) is hot when running, and that heat is conducting away through the water jacket, which is being circulated through the radiator. So in the steady state while running, the engine core is much hotter than the water jacket.

When you shut the engine off, that heat in the engine core conducts out to the water jacket as before, but there is no circulation now to take the heat away. There is also no new heat being generated in the core, so it averages out pretty quickly, but that is what you are seeing.

My electric fans hardly ever run. Mostly just when I am idling at a light on a hot day. But about 10 seconds after I stop the truck and turn the key off, the fans kick on for about ten seconds.

 

[350runner]

This^^^

Sent from the dust in front of you!

 

[Driver4r]

The core of the engine (pistons, bores) is hot when running, and that heat is conducting away through the water jacket, which is being circulated through the radiator. So in the steady state while running, the engine core is much hotter than the water jacket.

When you shut the engine off, that heat in the engine core conducts out to the water jacket as before, but there is no circulation now to take the heat away. There is also no new heat being generated in the core, so it averages out pretty quickly, but that is what you are seeing.

My electric fans hardly ever run. Mostly just when I am idling at a light on a hot day. But about 10 seconds after I stop the truck and turn the key off, the fans kick on for about ten seconds.

Pretty much what I said

 

[rich weyand]

Pretty much what I said

Understood. We are both describing the same reality, which we both understand. I just phrased it a little differently, in the way I think about it. I thought an additional explanation might help the OP because he indicated he couldn't understand why it would happen.

 

[Driver4r]

Understood. We are both describing the same reality, which we both understand. I just phrased it a little differently, in the way I think about it. I thought an additional explanation might help the OP because he indicated he couldn't understand why it would happen.

True true