Coolant loss

[3082a]

My 28 aa ar has a problem with coolant loss. I fill it up and after about 30 miles it starts to overheat from no coolant. I suspect the waterpump is over working. It is a restored original radiator and a rebuilt motor. What would you recommend for it? Would a thermostat slow that Dow ?

[pinball73]

There is a good video on utube about this very problem! it's not the water pump, it is the radiator! you need to have it rodded out! I had the one on my 29 boiled out & I still have the same problem as you do. watch that video & it will explain the problem.

[NCRebel]

The first question I have is, how much smoke does your car produce? Is it the typical white smoke that indicates water vapor in the exhaust? There may be a crack around the exhaust ports that the gasket is not sealing where the coolant is forced out rapidly.

My next focus would be on punctures on the radiator, hoses or pump. That can be found by the drips left when the car is running or sitting still. Good luck in finding and fixing the issue.

[1crosscut]

Hold off on all the fixing for a bit.

You may just be filling your radiator too full. A's will spit water out until they find a level they are happy with. Let it go for a while and keep an eye on the level. As long as the tubes are covered you will be fine.

Get a cheap dial or digital meat thermometer and pull the radiator cap often and check the temperature of the water. That way you will know for sure what the water temperature is. Quite common for folks to think they are overheating because of water being pushed out when the only problem is the radiator is too full.

[redmodelt]

Also coming into play is where you set the GVA and spark along with the fact it's a rebuilt engine, they will run hotter. If you are filling the radiator all the way to the top, don't do that. The T, A and even V8 want the water level just about to the bottom of the baffle to maybe a little above where it v's down. Over filled radiator will push the extra water out and find it's happy level.

[Licensed to kill]

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My new to me 31 sedan would puke water out resulting in a low level situation as well. In my case, it turned out the the rivet that holds the baffle in place had failed and the baffle dropped a bit. The pump was pumping the water over the baffle and straight out the overflow tube. Took the rad off, laid it on the bench and pryed the baffle back into place with a screwdriver through the inlet port, redrilled the rivet hole (to a larger rivet) and re-rivetedit with a washer on the inside for added support. Put a dab of silicone on the rivet head to ensure a seal and now I can fill with anti-freeze as it no longer pumps it out the overflow. In my case, I would fill the rad, start the car and it would start running out the overflow right away, long before any heat expansion and looking in the rad cap I could see the water flowing over the baffle.

[BILL WILLIAMSON]

A loose fitting, large head roofing nail in the top of the overflow tube, helps from "splash-over" coolant loss!--It's an OLD Time "fix"---
RUST FLAKES, in the top of the tubes is the most COMMON cause of overheating, back flush it, 1 or 2 times a year!
Bill Cool

[Bill G]

I agree with the advice to watch it and see. It might not be a problem at all. The Model A radiator does not behave entirely the same as a modern car. Mine did not lose a drop after I had the engine rebuilt and filled with water. All the way to the top. However, when I changed over to antifreeze for the winter, I lost a lot. Kept filling it to the top, and it kept spewing out. After reading all the advice here, I decided to just let it go. By golly, , sure enough, it does find its own level, just covering the tubes. I was mistaking the loss of water as over heating and boiling over. Not so. It actually runs as cool as a cucumber.

[steve s]

Originally Posted by BILL WILLIAMSON

A loose fitting, large head roofing nail in the top of the overflow tube, helps from "splash-over" coolant loss!--It's an OLD Time "fix"---
RUST FLAKES, in the top of the tubes is the most COMMON cause of overheating, back flush it, 1 or 2 times a year!
Bill Cool

Here's whereof Bill speaks:

[Houdini]

I had posted a similar problem I was having. I had used Prestone anitfreeze without any problem but then found my water pump needed replacement. After I replaced the water pump with a new one, I found the Prestone antifreeze was pushing out the overflow tube when the rpm was above idle and it got warmed up. Lots of foam. Some suggested I might have a leaking head gasket. But I didn't find that to be true.
So I went back to plain water and anti rust inhibitor and it ran fine, with the water level just above the baffles. I decided recently to put in Sierra Peak, as others have said where they had similar problem with Prestone and other anitfreeze, the Peak Sierra didn't bubble or foam. I haven't driven it much since i put in the new antifreeze, and so far, I don't see the foam problem. Runs cool, like it did with plain water, as well as when the old water pump was in it with Prestone. So as far as I'm concerned, my new water pump and Preston don't get along. I would loose significant water with it(way below the baffle). If you're using antifreeze, you might want to see if you have the same problem with just water, as a test.

[steve s]

Originally Posted by 3082a

My 28 aa ar has a problem with coolant loss. I fill it up and after about 30 miles it starts to overheat from no coolant. I suspect the waterpump is over working. It is a restored original radiator and a rebuilt motor. What would you recommend for it? Would a thermostat slow that Dow ?

Many possibilities, but we can say for sure that if you're overheating "from no coolant", it's not going to seek it's own level; something's wrong, and I seriously doubt if adding a thermostat is going to fix it--new Model A did not need one to avoid overheating.

One question is, which comes first: coolant loss or overheating?

The latter could be due to too-tight new motor (as suggested), retarded timing, dragging brakes, and probably many more things. Once overheating has happened once, the head can be warped, the gasket will then leak and/or blow, compression/combustion gases will then leak into the coolant system and further overheat and blow out the coolant, which will then cause terminal overheating. OR, the head and motor deck may not have been milled flat and the gasket not properly torqued down and sealed, so leaking compression would blow out the coolant without preliminary overheating. If leaking head gasket is the culprit, it often will show up as explosive coolant loss under load. NAPA sells a "block tester" to check for combustion gases in the coolant (be sure to buy also the "large motor" adapter to fit the Model A radiator filler opening).

OR, the radiator or somewhere in the block's coolant flow path is blocked. Did the "restoration" of the radiator include rodding out the tubes, and did the rebuilding of the motor include cleaning out the coolant path? If not, repair PROPERLY or replace. In my case, the motor rebuilder left a shop rag in the head!! Also, a repro radiator had too small of a hole cut out where the lower tank connected to the radiator outlet.

A quickie check for extremely blocked tubes is to run the flat palm of your hand across the front of the radiator: temperature should feel uniform horizontally and go from hot to not-so-hot from top to bottom (you can also use an IR temperature "gun"). Totally plugged tubes will be strangely cool from top to bottom, but this test may fail for partially plugged tubes. You would never expect the radiator of a modern car to last for 80-some years--just replace the thing and be done with it. Then, resolve not to plug it up again right away by pumping waterproof grease into it through the water pump grease fittings.

[Mike Peters]

Expanding on what Steve S says above, a friend rebuilt the engine and installed a new radiator in his coupe and immediately had the same overheating problems as 3082a. Long story short, the rebuilder never cleaned out the rusty water jacket in the engine, and upon starting the engine, proceeded to pump large rust flakes into the upper radiator tank, thereby plugging the radiator. The cure was a simple radiator backflush. Bill Williamson has stated the same thing. Rust in upper tank will drive sane men crazy!

[1crosscut]

One of the worst cases of over heating I encountered was cured by simply setting the timing correctly.