The Stovebolt Site Forums The Shop Area Engine Shop LOSING COOLANT

I have a 1941 chevrolet pick up with a 216 engine. Thermostat is a 160. New about 1 year ago. Radiator new 1 year ago.
I am adding antifreeze about every 3 months. I drive only on week ends no more than about 40 miles total.
There are no external leaks, and the truck does not smoke.
Temperature normal runs around 160-170 by installed gage.

Have yet to put temp gun on it to check accuracy.
Any thoughts or ideas appreciated.

do you have an overflow tank? How much are you losing? Correct me if i am wrong guys..... it is possible that you have it too full and when you are getting to operating temp, you are blowing out a little in warmer weather. I had this issue with a newer vehicle and it would dump it down to a certain level and never go lower then that.

This is a zero pressure system with no overflow tank.

yes, the question is how "full" are you trying to keep it? needs to be at least a couple inches down, and as long as the level in the tank is above the fins it's good .... also do check over the system with a laser thermometer to establish what the gauge is telling you

Bill

Boy, if we want to get a real debate goin on this one Bill,
see if my calculations are correct or where they are flawed.
The water in the radiator isn't gonna be 180°F but let’s just
simplify things for the purpose of discussion and say that
the 'system' average is a uniform 180°F. Using this high of
an average, would present a worst case scenario.
Water expansion, when heated and cooled is not a linier rate,
but again since we are not really concerned with extremely
small numbers we can use .00023% per degree F for an expansion
rate.
Now lets fill our cooling system with 60°F water and heat it to
180°F giving us a temperature difference of 120°F.
.00023 x 120 = .0276% expansion.
I’ll round off the system to hold 2 gallons or 128 ounces of
coolant.
.0276% of 128 ounces is 3.5328 ounces.
So…..filling our radiator with 60°F water and warming up our 216
to 180°F should add a little less than 4 ounces of volume to
the system.
Now we all know that, just above the cooling tubes in the
radiator to the top of the filler neck is a bunch more than
just under 4 ounces. And I’m sure, like me, you’ve all topped
off your radiator and let it seek its own level by letting the
access puke out the overflow. When mine cools down it ends up
just above the cooing tubes. In other words, the tank is 80%
empty and the tank is roughly 100 sq. inches which should hold
roughly 50 fluid ounces or a quart and a half.
So my question is, where is all this extra expansion coming from
if it should only expand by 4 ounces???

Denny Graham
All heated up in Sandwich, IL

Temperature of combustion for gas is about 477–536 °F.. therefore one would expect the coolant temperature in the areas adjacent to the combustion chambers is a lot hotter than your 180 F. figure.

kind of pointless to 2nd guess the designers and physicists Denny, but part of the flaw is in not taking account of the variation of the coefficient of thermal expansion with temperature & pressure, the 5-10* drop in temp across the rad, or the volume changes from pump agitation, as well as assuming the tank is right full when hot .... as you say, let it find its own level, it will always be well below "full" [cold] but above the tubes when the system is working properly, the mistake folks make is filling it right full when cold

and some related trivia: when pasteurizing juice in my large gas-fired kettle, I have to fill to a lower level when the ambient barometric pressure is rising or it will foam over ... a demonstration of pressure affecting expansion of a heated liquid

Bill

Just solve the problem by installing a puke can and pouring the overflow back into the radiator periodically. If the overflow tube is below the level of the liquid in the catch can, it should siphon the coolant back into the radiator every time it cools down.

Or- - - - - -keep beating a dead horse with intellectual exercises about physics!
Jerry

better to understand that the "problem" is being created by not understanding the system, just don't overfill the rad I've never found a need for an overflow setup, although most years GM offered them as an option - but I believe every year owners glovebox manual points out the level should not be "full", especially with an antifreeze solution - it may be that eyell saying "I am adding antifreeze about every 3 months" means there's a stronger then needed or useful concentration of antifreeze adding to the "problem" of overfilling

Bill

I am using a 50/50 solution. Just above the top row of tubes.

What ever the case, the level should stabilize in the radiator at some point, unless it is leaking somewhere, either externally or internally. It certainly won't stay completely full.

How about using a low pressure radiator cap?

At least put another 1 in front of those numbers, as in 1500F. And if the coolant got too hot, you would have steam pockets...not good!

Have you looked at your spark plugs. One or more of them will tell you if you are burning water.
Carl

I had a similar concern on my 49 216. In troubleshooting I added an overflow tank and haven't had to add fluid since. When cold the radiator is filled to the top. When it gets up to operating temp (180) it'll spit anti freeze into the overflow tank until it gets about 1.5"-2" lower in the radiator resevoir and stay there. It'll suck the fluid back in as it cools.
I've not had any over heating problems either.

I plan on adding a nice stainless or polished overflow tank one of these days but my temporary tank is doing a great job....
Dave

If your running it cold just above the tubes and there ain't any
dripin' on the floor and your still loosing it then I'd say you
either got a cracked head (very common) or a bad head gasket. A
small leak probably wouldn't show up in the exhaust. Many
people go thru a quart of oil every 100-200 miles and you never
see it in the exhaust in the day light.
Gez Jerry, just tryin' to have a little fun and put a little
life into the thread. Lot's of variables of course, thought
I pointed that out by saying that the numbers were average ball
park figures just for the sake of discussion.
I myself get kind of bored with curt one line answers without
any discussion or imagination slipped in every once in a while.
Be one hell of a boring bunch of forums if all we ever posted to
them was what was already printed in the service manuals.

Denny G
Sandwich, IL

Denny,

Despite Jerry being a stick in the mud (j/k), the rest of us got a little grin on our faces when reading it... ok at least I did! I even started to think wow, what a auto geek!

I think what you were trying to state was Charle's Law: which is defined as when at a constant pressure the volume is directly proportional to the temperature. ie as the temp increases the volume increases causing a radiator to vomit its green bile.

Have a great day wrenching guys/gals,

Chris

Doesn't Charles's law apply to gases, not liquids?
Jerry

You got me! Yes it does.

Don't know what laws apply guys, I'm just trying to put some
common sense to work, to explain where the additional expansion
is coming from.
Ran a test with the radiator topped off in order to better see
just how much expansion was taking place. Topping off the
radiator is a mistake which a lot of people make when they
first acquire a Stovebolt, which leads them to think that
they have a coolant leak.
The results are that an open container of water expands at the
rated which I calculated.
The expansion in a closed cooling system is about 4x the
calculated amount in free air.
I can't see where pump agitation would have anything to do with
the increase in volume. But as John brought up, the temperatures
in the head and surrounding the cylinders would be quite high
compared to the system average. So it appears that is where
the in crease in volume comes from.
Here are a few pictures from this afternoons activity:
http://www.pbase.com/dennygraham/coolant_expansion_experiment
Fun test for me and what I learned from it is exactly how much
the volume increases due to the thermal expansion with a
standard 180° stat installed.
Denny Graham
Sandwich, IL

Cool test Denny. Which btw matches my experience on a 49 216

Altho ducttape is world renowned for it's usefulness, my hillbilly temporary water bottle was a little better rigged, which is unusual for a hillbilly rigup but non-the-less, mine has somehow managed to stay somewhat permanent

The reason for my addition of an overflow bottle was to determine whether the coolant was being exhailed via the overflow port or if I had an internal coolant leak. It was winter and my 216 had a serious case of valve cover condensation around the oil filler port. Ends up the coolant was expelled via the overflow port until it reached it's happy spot when warmed up (just above the tubes) and not an internal leak. Condensation in my 216's valve cover during cold weather is SOP apparantly..

Anyways back to our regularly scheduled thread
Dave
Dang night shift gives me too much time on my hands...

As the Engine and Radiator warm up, they both expand also and increase the volume of Coolant they hold.

So as the Coolant expands, so do it's Hosts.


Otherwise, I too would lean toward a 'hairline' Crack in the Head or a very small seepage via a bad spot in the Head Gasket, allowing Coolant into one of the Cylinders.

Although, I would kind of think that would also mean, that at least some Exhaust would be going into the Cooling System, also, if that were so.

Have you had it running with the Radiator Cap "off", and got your Nose right down in to the opening there to see if any exhaust smells were coming out of the Radiator Cap Socket?


As 52Carl relays a few posts above - Have a look at your Spark Plugs and see if any of them look a little off deposits/color wise.

Since yours is a 'Free Breathing' ( non pressurized and is vented to the Atmosphere ) Cooling System, there will be some evaporation of course.

And, changing to a low figure Pressurized Radiator Cap will change nothing ( and or the Cap would not even fit anyway ).

Mine puke tank was just for the afternoon Dave. My
curiosity weren't worth spending the day to make up
a mount for a pop bottle, i.e., Duct tape. And you
apparently found, as we all did in the beginning,
before reading the manual, that old Stovebolt
will find that sweet spot for the water volume
all by her self. She's just like a horse, you can
lead him to water, but you can't make him drink. She
knows when she's full so stop trying to shove more
down her throat.

Think we've lost the one who initiated the thread Phi
Kappa Phi. Maybe that coolant loss ended when he stopped
topping off the radiator in the morning?

Denny G

Might as well try a simple, quick, cheap, easy, and "natural" solution first.
I think the 1941 Shop Manual manual says (in one place) to fill to 3" below the overflow pipe.?