Throwing coolant from top of radiator.

[KMeredith87]

So it's a beautiful morning and decided to take the A out for a ride. Fairly recent rebuild (under 1000 miles) so I decided to check the torque on the head. Maybe about half the nuts or so we're a little loose so no big deal torqued everything up to spec and off we went. Stopped for coffee and then got back in to drive off... Maybe two miles down the road at about 40 mph she started throwing coolant out of the radiator cap, the engine was barely warm and the coolant no where near hot or boiling. I'm at a loss here...when I built the engine I put the smaller pulley on the crank to slow the water flow from the water pump and took all other precautions to make sure (to the best of my knowledge anyway) this wouldn't happen. Any ideas??

[JOHN CT]

Are you over filling the radiator ? Water level should be below the baffle. The water can be getting hot and expanding.

[H. L. Chauvin]

Hi K,

Reply no. 2 good point.

Happens very very very very very very very (like Trump), often "if" one fills the radiator to the very top, or near the top.

Try just this first:

1. Drain coolant from radiator until coolant just barely covers tops of tubes.

2. Start engine.

3. Watch coolant flow over tubes ....... which means radiator is doing its job.

4. Drive off and report back your findings.

[Seth Swoboda]

I think John has it correct. Let your radiator find it's proper level of fill.

[Big hammer]

Over filled, over flow tube clogged? That's yucky looking coolant time for back flushing? Bad gasket on your cap? Hope you cleaned up that coolant from you paint!

[KMeredith87]

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I don't believe the radiator is overfilled as I haven't added water to it in quiet some time as I am aware of them finding their own water level but who knows, I did fill it to the same level that I would have with my old engine in the truck so it may be still high, I'll drain some and try again.

As for back flushing the block, I am up for doing it but not sure how with the A's....both my old engine and this one hay I built have given me that nasty coolant color so I don't know if I'm doing something wrong...

[Tom Wesenberg]

If you are using plain water, it will rust within minutes.
I would only use 50% antifreeze, even if it never got below 80*.

[H. L. Chauvin]

When you report:

"I did fill it to the "same" level that I would have with my old engine in the truck."

Please forget about your truck, and look at it this way:

You have (2) cups.

Cup A has a 2" hole in the bottom.

Cup B "had" a 2" hole but now it is partially plugged and it has a 1/8" hole.

You pour equal amounts into each cup at the exact same rate.

Water gets close to the top rim in Cup A, but never overflows.

What happens with Cup B with a clogged opening causing reduced flow?

[1931 flamingo]

If the rad cap gasket was good that wouldn't have happened, although if you're throwing water it would have gone out the overflow tube. Does your rad have a baffle?? Is the o/flow tube "formed" to the rear??
Do you have "Bill's" nail inserted??
Let us know please.

Paul in CT

[Doug Linden]

Paul is correct, the radiator cap gasket is supposed to provide a seal between the cap and neck that will not leak. Coolant level just below the baffle will probably be the best place for normal operation and eliminate any coolant blowing out the overflow tube.

[mshmodela]

I had the same problem.. I replaced cap to radiator gasket and the quail gasket I had to make my own from a large rubber washer to get a seal, but not too thick to put extra stress on the quail hinge... Not a drop coming out since.,

[KMeredith87]

I will have to drain and flush the system for sure but I did also notice some water seepage from around the head after I shut it down. As for the water level I generally keep it just below the baffle and I do have the large head nail in the overflow tube as suggested, one of the best things I did years ago....additionally I do not have the red gasket under the top half of my cap because it never sealed but had a rubber one made for it that has alas at sealed well.

[captndan]

If the engine and radiator are completely empty and then filled there will probably be an air bubble somewhere. You think it is full but it's part air. When the radiator burps it will appear low. This is where over filling comes in. Burp your baby or it will spit up on your shoulder.

[Zener424]

My radiator was missing the baffle. I soldered in my own baffle. Does yours have the baffle installed?

[BILL WILLIAMSON]

Sometimes mysterious leaks at the cap area is caused by a crack, where the neck is SOLDERED to the top tank. I fixed Minervas' with my handy propane torch.
Bill Blueflame

[H. L. Chauvin]

Hi Bill,

Would be interesting to hear what Buster-T Propane thought about Mr. Bill Blueflame's soldering job?

[Chuck Sea/Tac]

"Water leaking around the head?" Where exactly? Do you see bubbles in the radiator when you run it at say half speed.( full over baffle, and looking into radiator).

[H. L. Chauvin]

The Model A was designed as a non-pressurized cooling system.

FWIW:

A "clean", "full flowing" radiator, with water just covering the tops of "clean" full flowing tubes can run a good Model A engine for months with "No" radiator cap, no thick seal, and never lose water "if" the overflow tube is just below the top of the radiator opening.

I saw quite a few Model A's and vintage tractors with non-pressurized systems running around comfortably with no radiator caps at all years ago.

Per reply no. 8, your radiator, like Cup B. is plugged, obstructing coolant flow, needs cleaning and will continue to over flow until it is cleaned.

[BILL WILLIAMSON]

Originally Posted by H. L. Chauvin

Hi Bill,

Would be interesting to hear what Buster-T Propane thought about Mr. Bill Blueflame's soldering job?

H.L,
After gettin' used to the hissing flame he looked at me, as if to "say"--"Ur you gonna use thet HIGH TONED Silver Solder, sumbody on the BARN sed it's STRONGER"?
Bill Blueflame

[31 Model A]

Originally Posted by BILL WILLIAMSON

Sometimes mysterious leaks at the cap area is caused by a crack, where the neck is SOLDERED to the top tank. I fixed Minervas' with my handy propane torch.
Bill Blueflame

That might be what's wrong with Sarah.....last winter Larry put in a new Rad and everything was just fine afterwards for awhile. I started getting seepage down the passenger side and the fan would blow the coolant back. I replaced the rad cap and base, didn't help, reset it, didn't help, made sure the water level was below the baffle, didn't help. When Larry came for her this winter, she went on his trailer. While on the ferry crossing the Mississippi, there was coolant dripping on the trailer and onto the ferry....might very well be a crack like you said showing it to be from the road trip, engine off. Larry hasn't got back with me yet on the cause.