Coolant always cold - but normal temperature

[bodomalo]

Hi

I am more than confused with my engine coolant level, it seems to me the engine does not use/need coolant at all.
Even after driving trough death valley (117 degrees outside temp.) the engine showed a normal temperature on the display (centered between H and C), but the engine coolant is cold and at FULL level COLD (low). It never uses the coolant anyway??
Can anyone explain that?

When starting the engine it first shows Cold, and after 1-2 minutes driving it shows normal temperature. When driving a very steep road the extra fan starts to cool the machine, sounds okay, temperature normal.

Shouldnt the coolant boil in that reservoir?

Bodo

[wolfe10]

Yes.

Check coolant level by removing radiator cap with engine COLD. It should be right at the very top.

[bodomalo]

JFreitas wrote:
Technical Report No. 2


* If reservoir level does NOT CHANGE between hot and cold, radiator level is low.

Recommendations
* Radiator level should be checked (by removing cap) at every oil change (Caution: Open only when cold. Contents under pressure.)
* Reservoir level should be checked for HOT and COLD level at every fueling. (Cold level should be checked before starting a day's trip before start up.)
* Radiator level (as well as all fluid levels) should be checked before and after storage of one month or more.

So radiator level in the system might be low and I should open the pressure cap and fill in some more... thats what I understand.

[JFreitas]

Technical Report No. 2

Note: This is the second in a series of Workhorse Technical Reports with information that Workhorse considers most important in helping motor home owners avoid potential problems and maximize the economy, safety and enjoyment of their driving experience.
Key maintenance check: How the motor home
coolant overflow reservoir works

Coolant overflow reservoirs were added to vehicles to make cross flow radiators more efficient. This is done by assuring that the radiator is full to the fill cap at all times during operation. To ensure the most efficient radiator operation and prevent any potential cooling problems, the operator should understand how the system works and see that it is regularly checked. Here is a brief explanation of the radiator-reservoir system and what to look for in checking proper fluid levels.

Coolant movement from radiator to reservoir
Coolant flow from the radiator to reservoir occurs when the coolant expands from heat. The expanding fluid opens the radiator spring loaded cap and flow occurs in a tube from radiator to reservoir. (The overflow tank is often called an EXPANSION tank.) This fluid movement occurs due to a pressure build up from expanding coolant. The pressure is NOT the result of boiling coolant.

If the radiator is low, the expanding coolant will build pressure in the radiator, but often insufficient pressure to lift the pressure cap. (Air is compressible—coolant is not.) If pressure exceeds the 15 psi cap, only air and not coolant will escape to the reservoir. Thus, the recovery system will not work when radiator level is low enough such that expanding coolant does not empty the trapped air from the radiator.

Coolant movement from the reservoir to radiator
When the coolant in the radiator cools, it shrinks in volume and creates a vacuum in the radiator. This vacuum pulls coolant from the reservoir back into the radiator through a one-way check valve in the cap.

If the radiator level is low, the normal pressure produced from normal engine operation will decrease and a sufficient vacuum will not be produced to pull the coolant from the reservoir.

Conclusions
* Coolant recovery system is inoperative when radiator is sufficiently low on coolant.
* Coolant tank can be at full mark at the same time that radiator is low enough to cause overheating.
* If an operator fills an empty reservoir, he must check radiator level to assure that it is full.
* If reservoir level does NOT CHANGE between hot and cold, radiator level is low.

Recommendations
* Radiator level should be checked (by removing cap) at every oil change (Caution: Open only when cold. Contents under pressure.)
* Reservoir level should be checked for HOT and COLD level at every fueling. (Cold level should be checked before starting a day's trip before start up.)
* Radiator level (as well as all fluid levels) should be checked before and after storage of one month or more.

[pointrow]

I've had several engines that the overflow tank never changes. If your temp gage reads normal and there is no other signs of overheating or coolant loss enjoy your RV.
Sounds to me that someone actually designed a coolant system that is large enough to do the job.

[chuckftboy]

The coolant in the overflow bottle really never should feel very warm. What is in the bottle is generally cool and the little over flow from expansion quickly mixes and won't feel very warn to the touch. Sounds like your coach is just fine.

[bodomalo]

wolfe10 wrote:
Yes, you have a problem if the level in the overflow does not change between cold and hot.

As suggested, air in your radiator can absorb the expansion as coolant heats (the most likely reason). But, if removing the radiator cap with the coolant cold shows coolant in the neck (no air) that is not the probable cause.

You can pull the hose out of the overflow reservoir and off the radiator neck, suck on one end with your finger over the other end to verify that the hose is OK.

you mean to check if there is a hole in that system? but wouldn the coolant then just spill out somewhere under the RV?


I will try a longer drive tomorrow and see if the level changes. At least today we recognized a change of lets say 1/2 inch after the motor cooled down again.
But - the coolant in the overflow should be warm I guess, but it isn't.


So anyway, do I have a problem of overheating the engine now at this point? I would have never recognized that problem so far, normal temperature, AC works, heating works. Just as I began to think I should one day check that coolant level I thought: Shouldnt that be warm after driving...

[wolfe10]

Yes, you have a problem if the level in the overflow does not change between cold and hot.

As suggested, air in your radiator can absorb the expansion as coolant heats (the most likely reason). But, if removing the radiator cap with the coolant cold shows coolant in the neck (no air) that is not the probable cause.

You can pull the hose out of the overflow reservoir and off the radiator neck, suck on one end with your finger over the other end to verify that the hose is OK.

[jplante4]

I'm gonna go with a hole in the pickup tube that is stuck down into the overflow tank.

[rgatijnet1]

You may have an air bubble in the radiator that is taking care of the expansion of the coolant.
The plastic tank is an overflow tank and is used to take excess coolant out of the radiator when the coolant is hot and allow it to suck back in to the radiator as the coolant cools down.
If there is any air in the radiator, it will not function as designed.
The normal operating temp of your coolant is around 200 degrees so driving through 117 degree heat should have a negligible affect on a properly operating cooling system.
You have an electrical cooling fan in the front of your radiator that comes on with the AC unit when the temperature increases in your cooling system.
There is also a fan clutch that will lock up your engine driven radiator fan when your coolant temperature reaches 107-110 degrees. This may only happen during a steep climb.
You should have been able to take off the radiator cap with the engine cool. You may have to press on it while turning it. It is probably a 15 pound pressure cap.

[bodomalo]

BTW: I also opened the pressure cap when the motor was cold (or I tried, as I wasnt able to open it completely) and some liquid came out there (very slowly). I closed it then.
I never see any liquid under the RV, its not loosing anything.

[bodomalo]

wolfe10 wrote:
Bodo,

Please share with us what coach/chassis you have.

Is the reservoir you are checking an integral part of the cooling system or an overflow reservoir?

Does the level in the reservoir change between cold (before engine started) and just after you shut it down (engine hot)?

And, with a pressure cap, coolant should NEVER boil. The function of the pressure cap is to raise the boiling point. Same for coolant-- the correct 50/50 mixture boils at a higher temperature than plain water.

It is a Fleetwood Fiesta 2006 - Workhorse Chassis W16
It is an overflow reservoir as I understand.
Orange Dexto Cool is inside, was always at level COLD, now after 3 months parking the level was a little bit under COLD (just a few millimeters). Beside the coolant there was also some black dirt inside that tank, some mixture of oil/grease/sand I guess. I opened that reservoir today, cleaned it and have add new coolant (50/50) into it.
I filled it to about 1/2 inch above the COLD mark.

Still, when I start the engine and bring it to normal temperature (takes about 2 minutes), the level in that overflow tank is always the same. It never rises to HOT.
But the manual says, that the level should be HOT when the engine is warm.

[wolfe10]

Bodo,

Please share with us what coach/chassis you have.

Is the reservoir you are checking an integral part of the cooling system or an overflow reservoir?

Does the level in the reservoir change between cold (before engine started) and just after you shut it down (engine hot)?

And, with a pressure cap, coolant should NEVER boil. The function of the pressure cap is to raise the boiling point. Same for coolant-- the correct 50/50 mixture boils at a higher temperature than plain water.

[jplante4]

Take the radiator overflow tank out of the rig and wash it out. Most likely what you're seeing is not coolant but crud/rust in the tank.

If that's not the case, then the radiator is not sucking the overflow coolant back in when you cool down. This can be caused by a bad rad cap or a plugged or leaking pickup tube.

[WyoTraveler]

It depends on the vehicle. Many gas use a 193 thermostat. It would be nice to see numbers.