Disappearing water

[rcsteuer]

i recently completed a frame off restoration of a '49 - 3A.  Runs like a top and looks great but I've got a problem with water.  I've had to add a gallon of water twice now (in 500 miles).  There is no sign of a blown gasket (no bubbling in radiator), no water in the oil pan, and certainly no water on the floor.  My only guess is that it's going out an exhaust port and through the tailpipe.

When the engine was done, the block and head were both magnafluxed for cracks - neither indicating an issue.  Does anyone know if it's possible for the block to be cracked in an exhaust port that might cause the water to be pulled into the port, then pushed out the exhaust?  I pulled the head off after the first couple hundred miles, resealed all head studs and the same with all exhaust studs, just to be sure it wasn't a leak around any of those.

Any thoughts would be appreciated.

[Ron D]

I always thought water out the tailpipe produces steam (white "smoke")?
What do the spark plugs look like?

Stock 4-pound pressure cap on the radiator?

[rcsteuer]

No steam (that's noticeable) and used a new 4 lb cap. If it was a cap issue, I do believe I'd be seeing water all over the floor as it bypassed the cap.

[rcsteuer]

And plugs are a nice tan (or brownish) color.

[Ron D]

Maybe do a cooling system pressure test like this?
https://www.youtube.com/watch?v=UStbSubWwLA

Or maybe a cylinder leak down test like this?
https://www.youtube.com/watch?v=J9aKM4znvWU

Where are you located?
Desert southwest where the temperature this time of year sucks water out of everything?

I'm out of ideas.
Good luck!

[Rus Curtis]

So far all good steps to troubleshoot. 

What I read is you added water. 


Did you have antifreeze in the mix?  Did you see a rise in the oil level on the dipstick?

[rcsteuer]

Ron D: Thanks for the links.  Before posting, I did run a cooling system test with the 4 lb cap and I do lose pressure after a while (45 min.).  No signs of leakage an nothing ends up in the crankcase. No cylinder leak test equipment available, but previous compression tests all indicate solid and consistent numbers between cylinders. It's been a while since I did it, so don't recall for sure but seem to recall results ran around 125 psi. I live in VT which seems to be like the desert Southwest these days.

Rus: Yes, only added water. Took the antifreeze out of the system with the first sign of needing to add a gallon of water.  Running straight water until I figure out what's going on.  Definitely not getting into oil.  Level has not changed, and oil is nice and clean.

[Ron D]

Results of your cooling system pressure test seem normal to me (as does everything else you've described).
Cylinder leak down test kit isn't huge expensive (assume you already own an air compressor).

Instead, maybe try a coolant UV dye test kit like this one (watch entire 3 minute video):
https://www.youtube.com/watch?v=rDuGeQnMOzk

Put the dye in the radiator and take a long drive to get the motor up to temp then search carefully for leak.
What temp thermostat did you install?

Assuming you always drive long enough to get the motor hot, and I don't see how this would be possible without also showing white smoke (--- just spit-balling), but is your muffler full of water?
That much water has to be somewhere.

I also recall reading somewhere that an emissions test (probe in tailpipe) can detect water.

Do you have a cab heater core installed?

Good luck!

[SteveKfl]

I was wondering the same thing about the muffler-full, or not seeing steam.  It has to go somewhere.  Do you have a "catch can" on the radiator's overflow/pressure release tube?  Could it be blowing past the cap?  I'm thinking "new" is not always "good" these days.

[Rus Curtis]

 I like the idea of the UV die.  Perhaps wherever it's leaking out, there will be residue that can be seen - even after it's dried.

[rcsteuer]

Thanks for the feedback.

Ron: I'll give the dye test a try. Maybe, if it's coming out of the exhaust, it'll show up (that's being really optimistic, even if the water is being spit out the tailpipe). Don't know about the muffler being full without pulling exhaust apart - maybe someday, but not today.  I get what I would consider normal drips out of the tailpipe while cold but those dissipate after it warms up. I have a heater core, but it's sitting on the garage floor. Another rainy day project.

Steve: Water doesn't drip out of this thing anywhere. I'd have a flooded garage if it did.  I agree, it has to go somewhere.  Where is the rub.  I have the original cap on it (also 4lb) and no difference.

Rus: Keeping my fingers crossed.

[Chuck W.]

Just thinking out loud, are you sure you didn't just have an air bubble in the coolant system? Did you remember to drill a vent hole in the thermostat?

[binthere]

You do know that the water level in the rad is just about 1/2in. above the cores. If you fill it to the top, it will just boil out the overflow tube till it gets to the proper level.

[SteveKfl]

Just tapping on the muffler would suggest whether hollow or "sound subdued" by water in it, and at what level (if any).  I was thinking of the "blow by the cap" when on the road at speed, not necessarily parked to puddle.  A clear bottle on the tube would tell that story or not.  If the tube is below water level in the bottle, upon cooling off it could suck it back into the system.  I would just use the bottle to "catch the symptom" for "testing purposes".  If that is the issue, then you can leave the water level in as is, empty the bottle, and make another teat a later day to see if it repeats, or was just too full.
 
Maybe the "air bubble" was the problem"?  Filled with engine running and at operating temp? Good Luck!

[Ron D]

I agree with Steve and binthere.
Filling your radiator to the top (overflowing) is a little (not a gallons' worth) too much.
If you overfill it, the cooling system naturally "seeks" it's happy full level by expelling the excess out the overflow tube when driving, and a dye test kit should reveal that.

I believe drilling the small hole in the thermostat is a good idea, but I understand it's purpose is as a water-pump bypass that allows some coolant to flow before the thermostat opens, and this enables more even engine warm-up, a good thing.
I think it can also help prevent an air bubble in the system that could interfere with filling the system completely until the bubble breaks.
As much as you've been driving yours already, I can't imagine a bubble is the issue, but who knows?

On water sitting in the muffler, you could drill a small drain hole in the tin at the lowest point and see what happens.
And then seal it with a dab of JB Weld.