Losing Coolant

[ryanheacox]

Losing coolant has been an ongoing problem in my Fordor and it's time to finally take some bigger steps to fix it. I switched back to antifreeze yesterday and in a 20 mile drive it lost a gallon. Based on the way the pistons and valves looked when I did the head gasket in May, I don't think it's eating water but it also isn't leaking out.

Also, I added that gallon of water at the bottom of about a 2 mile hill before my house and by the time I got home there was no water in the top tank of the radiator.

My only other thought is that things could be plugged up and water is just getting pushed out the overflow? The engine was running great, plenty of power and very smooth yesterday. I figured it would run badly if it had to burn a gallon of antifreeze over 20 miles? I would very much appreciate your input.

[Marshall V. Daut]

The #1 question that should first be asked in such cases is: Did you fill the top radiator tank to the neck? If so, that's the problem. The coolant should just barely cover the top of the fins inside the top tank, i.e., just above the bottom of the top tank. Hot water needs to expand and will do so according to Boyle's Law (?). That's why you need a lot of expansion room in the top of the radiator tank. If there's too much water, not only will the excess water force its way out, but also more water beyond that. It's like a puking action that once it gets started, doesn't stop until it has reached its natural level. Try putting only 2 1/2 gallons of coolant instead of three after draining the system. Then try the hill again.
I also assume that like about 98% of the Model A's in restorers' hands these days, there's a fancy Flying Quail or Motometer radiator cap in place, right? The two-piece design of these split caps almost invites hot water to find the easiest path out. If you're concerned about the radiator not doing its job because of plugged tubes or loose fins, replace that fancy cap with a plain slightly-domed one that came from the factory. Then test drive with 2 1/2 gallons of coolant. If you don't lose any coolant, then the higher level and/or the split cap is at fault. If with the flat cap the water still rushes out, the radiator is clogged. Possibly the water pump is operating too efficiently via its impeller blades and is pushing more water through the upper neck than the radiator can handle. In such a case, insert a 160 degree thermostat in the upper radiator hose. That will slow down the flow if it is too much for radiator.
Let us know what you find out.
Marshall

[Bob C]

Do you have a baffle in your tank?

Bob

[BILL WILLIAMSON]

Put a ROOFING NAIL in your overflow tube!
Bill W.

[Synchro909]

Guys, the OP says that the pistons etc look as though water is finding its way into the cylinders. That pretty much eliminates top tank, overflow etc.
If you replaced the head gasket as recently as May, have you retensioned the nuts to 55 ft pounds and did you do it several times?. Is water getting into only one cylinder? If so, it's around there that you should start looking. The only other way water can get into the cylinders that I can think of at short notice is through a crack in a casting - head or block or maybe rust has eaten a hole though the cast iron, allowing water to enter.

[jthomas6]

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Originally Posted by Synchro909

Guys, the OP says that the pistons etc look as though water is finding its way into the cylinders. That pretty much eliminates top tank, overflow etc.

Actually, he said it wasn't getting into the cylinders - -
"Based on the way the pistons and valves looked when I did the head gasket in May, I don't think it's eating water but it also isn't leaking out."

I had a similar situation, found that sometime in it's previous life - someone had broken the overflow tube right where it comes through the baffle. I tried to patch the break, only made it worse - ended up putting in a modern overflow tank. All's well, when running hard, it fills the tank, then when shut down it flows back into the radiator.

[ryanheacox]

Marshal, I have a thermostat somewhere, I'll give that a shot if I can find it.

Bob, yes, the rad has that baffle in the top tank

Bill, I really like the roofing nail idea, simple and it'll tell me exactly what I need to know

Synchro, I probably could have said that better. It did not look like water was getting into any of the cylinders but it's also not leaking externally when it just sits. I'm going to re-torque the head again either way. I check it periodically, maybe once every month

[Mitch//pa]

You never mentioned how high your filling the top tank.>..

[ryanheacox]

I've filled it up to the neck, and I've filled it to just over the top of the tubes. But, last night it took a gallon to come just over the top of the baffle.

[springerpete]

Marshall: In case you are interested, it is Charles' Law. Boyle's Law deals with pressure and volume. I think it is Murphy's Law that applies in most other instances. Bill

[Greg Jones]

I just went through this and my conclusion: I was overfilling the radiator. The correct water level is just covering the top of the tubes just as Marshall says. So...it will unnerve you when you open your radiator cap and it will look too low. Since I have learned the proper coolant level, I have not lost any coolant and no more spitting and slobbering all over the hood and the windshield. I agree with Marshall on the "split cap" explanation-they are more difficult to seal and easier to leak than the stock radiator cap. I would recommend you drain the system and carefully measure the coolant going back in (2 1/2 gallons per Marshall) and DO NOT ADD MORE. In my case, if I can actually see coolant in the radiator, it is overfilled.

[Mitch//pa]

Test for combustion gases in the radiator.. If that passes I would seriously look into a radiator issue.
You shouldn't be losing a gallon on a twenty mile ride with it filled at the baffle level

[H. L. Chauvin]

Hi Ryan,

Had "similar" Model A radiator coolant loss problem with no noticeable coolant leaking into crankcase, no coolant leaking on garage floor at night when parked and no coolant leaks when engine was idling.

When Model A water pump impellers rotate faster at higher engine rpms, the coolant flows faster through Model A water pumps; hence, coolant levels can slightly "rise" upwards in the upper radiator tank.

My Town Sedan's original radiator came with the baffle about 75% rusted out.

Next my overflow tube was much shorter that the correctly positioned & indicated overflow tube in above Reply No. 4.

One vintage "fix' was to slip a rubber hose extension over your overflow tube if it is short ..... then for double protection, Mr. Bill's reply no. 4 above with the roofing nail usually helps to decrease coolant exiting the overflow tube.

I installed "both" a rubber hose extension upwards on my short metal overflow tube, and provided a brass wood screw in the top of my rubber hose ....... have no thermostat ... fill radiator to cover radiator tubes with about 3/4" of coolant, and no more loss of coolant on even 200 mile trips in one day.

[Jim/GA]

Originally Posted by ryanheacox

Losing coolant has been an ongoing problem in my Fordor and it's time to finally take some bigger steps to fix it. I switched back to antifreeze yesterday and in a 20 mile drive it lost a gallon. Based on the way the pistons and valves looked when I did the head gasket in May, I don't think it's eating water but it also isn't leaking out.

Also, I added that gallon of water at the bottom of about a 2 mile hill before my house and by the time I got home there was no water in the top tank of the radiator.

My only other thought is that things could be plugged up and water is just getting pushed out the overflow? The engine was running great, plenty of power and very smooth yesterday. I figured it would run badly if it had to burn a gallon of antifreeze over 20 miles? I would very much appreciate your input.

Ryan-
Roughly how fast were you driving today when you lost the gallon of coolant?

Especially on that downhill run.

I have seen many Model A's that do not lose a drop of coolant for weeks and months, unless the vehicle speed gets above about 35 to 40 MPH.

[Tom Wesenberg]

I would retorqued the head, then add a clear plastic line to the overflow pipe, and run it into a gallon jug. This will let you know if you are loosing the coolant out the overflow.

[Marshall V. Daut]

"Springerpete " -
That's for the correction. Now you know why I didn't major in physics.
Marshall

[ryanheacox]

I noticed the motometer begin to spike in town but before that I was driving between 45-50MPH. It made it almost the entire trip running normally, only started heating way up in the last 3 miles.

I did a quick and dirty sniff test for combustion gasses but I really should take it to a shop

I'll drain the coolant that's in it when I get back home on Friday and measure it

[ryanheacox]

Will do Tom, I'll try that Friday as well

[eagle]

Your radiator cap should NOT leak. Any coolant pushed out should be from the overflow tube. Check that the cap seals properly first. Then do like Tom says, push a rubber hose on the overflow tube and run it to a jug tied to the radiator support rods. Don't plan on this being permanent, this is simply for testing and troubleshooting.

[Mitch//pa]

It should be very obvious if it's coming out of the cap versus the overflow pipe at the bottom..