Is your radiator overflow tank level dynamic? (2 Viewers)

[Bambusiero]

Is your radiator overflow tank level dynamic?
Does your coolant system push coolant out every time you drive?
(And pull it back on every cool down?)

Asking any willing observers to report back how your truck behaves.

Here is the procedure (it's quick and easy):

From a fully cold start - engine at ambient temperature.
1) Pop the hood and check your overflow tank level.
2) Start up and drive about 3-4 miles.
(My coolant temp is barely getting to 186F at this point)
3) Pull over, pop the hood, and check coolant overflow tank level again.

Is it up from starting level?
How much? [inches, cm]

Mine is up 1/2" every time.
Much more as the trip progresses. Up 2 1/8" on an hour long 70mph freeway run.

 

[Tools R Us]

That is how it should work, sometimes called an expansion tank. If it didn't do that, there is a problem, leak, etc.

 

[Red Merle]

yes

 

[Red Merle]

There is probably a good science class lesson here, but the bottom line is that it is normal. As long as it is barfing out clean coolant, you just don't need to do anything.

 

[sunrk]

The level in the tank is meant to change. Water expands/contracts as it heats/cools. One interesting property of water is when it freezes it expands, but that's why 'coolant' is often called, or has as part of it's chemisty, 'anti-freeze'.

 

[Qball]

The level in the tank is meant to change. Water expands/contracts as it heats/cools. One interesting property of water is when it freezes it expands, but that's why 'coolant' is often called, or has as part of it's chemisty, 'anti-freeze'.

Actually water or most liquid expands and contracts very little when heated or cooled. However it does change volume when it changes state. When frozen water molecules lines up and creates crystals which will take up 10% more space/volume. This is why your water pimple will burst if frozen. When water starts to boil and becomes gas/steam at sea level, steam will have 1600 times the volume compared to when it was water.

So the reason for the overflow tank level goes up is because your coolant boiled over a little and pushed some coolant out. After the engine cools down then the coolant system will suck coolant back in because steam becomes water again and loses volume and create a vacuum.

 

[sunrk]

It's not 'boiling over' as it's a pressurised system which, combined with the chemicals added to the water, prevent boiling at temperatures well over 100 C. If the cooling system looses it's pressurisation, then it actually does boil.

You're correct that when water changes state from liquid to the first gaseous state, it expands up to 1700 times it's volume. That's another reason you do not want engine coolant to actually boil.

 

[Desert Dino]

yes the same here

the only thin is there is evaporation during time from the expantion tank and you get there a viscus oily liquid i add distilled water

 

[Qball]

It's not 'boiling over' as it's a pressurised system which, combined with the chemicals added to the water, prevent boiling at temperatures well over 100 C. If the cooling system looses it's pressurisation, then it actually does boil.

You're correct that when water changes state from liquid to the first gaseous state, it expands up to 1700 times it's volume. That's another reason you do not want engine coolant to actually boil.

If your look under the Oem cap the pressure should 18 psi which is 1.1 bar or aptomstphere pressure. That’s enough to raise boiling point of 50/50 coolant from 223 to 271 degrees. However if you have straight water in an emergency 18 psi cap will raise boiling point from 212 to 260.

Normally yes we should not have coolant boil or have temp of 271 but if you over heat a little at 220-230 degrees at temp sensor then it’s entirely possible to have 271 degree coolant temp in your engine. Remember your temp is coolant temp at the sensor which is AFTER the radiator.


For the most part you should not have much coolant get pushed out, in fact your over flow tank level should be quite steady with slow decrease during summer time due to a little coolant lost in form of steam.

 

[Desert Dino]

If your look under the Oem cap the pressure should 18 psi which is 1.1 bar or aptomstphere pressure. That’s enough to raise boiling point of 50/50 coolant from 223 to 271 degrees. However if you have straight water in an emergency 18 psi cap will raise boiling point from 212 to 260.

Normally yes we should not have coolant boil or have temp of 271 but if you over heat a little at 220-230 degrees at temp sensor then it’s entirely possible to have 271 degree coolant temp in your engine. Remember your temp is coolant temp at the sensor which is AFTER the radiator.


For the most part you should not have much coolant get pushed out, in fact your over flow tank level should be quite steady with slow decrease during summer time due to a little coolant lost in form of steam.

IIRC the sensor is not after the Rad but before it goes to it from the engine, i have dry sensor and the readings are the same vs OBD1 sensor reading

 

[Qball]

IIRC the sensor is not after the Rad but before it goes to it from the engine, i have dry sensor and the readings are the same vs OBD1 sensor reading

Ah I could be wrong on that, I still haven't had to replace my temp sensor yet. Somehow I heard it's after some where here on mud.

 

[Tools R Us]

If your look under the Oem cap the pressure should 18 psi which is 1.1 bar or aptomstphere pressure. ...

The cap should be .9 or ~13psi.

 

[Tools R Us]

Ah I could be wrong on that, I still haven't had to replace my temp sensor yet. Somehow I heard it's after some where here on mud.

The OBD2 sensor is in the lower edge of the head, at about cylinder #2.

 

[Qball]

The cap should be .9 or ~13psi.

Really? I swear my new(2 years agao) OEM cap says 18psi, gonna have to open it to validate.

If that's the case then the boiling point for coolant goes down to 223 at sea level and lower with higher elevation.....which seems a little low.

 

[ZackR]

Yes. When cold I leave my expansion tank at the "low" mark so that it has room to expand when hot, which it does. The next morning it will be back to the "low" mark.

Totally normal operation.

 

[Tools R Us]

Actually water or most liquid expands and contracts very little when heated or cooled. ...

True, but it's slightly more complicated, the liquid is contained in a vessel, made of a variety of materials, that all change with temp. The end result is; the level in the coolant tank is higher when hot and lower when cool.

 

[Tools R Us]

Really? I swear my new(2 years agao) OEM cap says 18psi, gonna have to open it to validate.

If that's the case then the boiling point for coolant goes down to 223 at sea level and lower with higher elevation.....which seems a little low.

They make more than one cap, you wouldn't be the first who was given the wrong cap.

 

[Qball]

They make more than one cap, you wouldn't be the first who was given the wrong cap.

True, but it's slightly more complicated, the liquid is contained in a vessel, made of a variety of materials, that all change with temp. The end result is; the level in the coolant tank is higher when hot and lower when cool.

My overflow tank level doesn't really change much every time I checked however a higher PSI cap could explain this.

 

[Rifleman]

Yes. When cold I leave my expansion tank at the "low" mark so that it has room to expand when hot, which it does. The next morning it will be back to the "low" mark.

Totally normal operation.

Mine operates like Zacks does, before starting the motor for the first time in the morning it's level with the low/cold mark, during operation it's level with the full/hot mark. The following morning when the motor's cold again it's back level with the low/cold mark.

 

[mudgudgeon]

It's not 'boiling over' as it's a pressurised system which, combined with the chemicals added to the water, prevent boiling at temperatures well over 100 C. If the cooling system looses it's pressurisation, then it actually does boil.

If your cooling system is in good condition, you can run it without a radiator cap, without it boiling. I currently have a split top tank on my radiator, so it's not pressurised. Coolant has leveled out at the split, about 1" below the top of the tank.
Having it pressurised gives you more of a safety margin to prevent boiling over, adding a higher pressure rated cap can increase that margin.
Water begins to vaporize well before it boils. Having a pressurised system prevents vapour escaping and keeps the vapour trapped.

Really? I swear my new(2 years agao) OEM cap says 18psi, gonna have to open it to validate.

If that's the case then the boiling point for coolant goes down to 223 at sea level and lower with higher elevation.....which seems a little low.

I'm confident mine has its original cap on it, it's stamped .9