Belching Radiator

[psimet]

This year has been the cooling system issues year.

I am now running a replacement radiator which is believed to be an older Re-cored radiator. I have a leakless pump I installed this spring. I flushed the block during the radiator change.

Changed radiator because other was overheating. Could hear water gurgling and possibly boiling after shut down, etc and it was an old repro radiator.

I slowly have gotten this car running and I drive it in short rides around the neighborhood when I run it.

Since swapping the radiator I will pull it in to the garage, shut off the gas valve, and let it mostly run the gas out of the carb. When it starts to speed up - running lean- then stutter a bit I shut off the ignition. After I shut it off and everything comes to a halt I’ll start getting some water out of the overflow.

First time it was a couple drops/ small amount. Last time I took it on a longer trip - longest it’s been on but still only like a mile or two. I got maybe a cup or so of water out.

I’m running water with water wetter. After the first time I looked and the water was just barely over the baffle in the radiator. I know A’s will sort of seek their own level in the radiator. I haven’t checked where the water is now but after that last bit I’d guess it’s just below the baffle or even with it.

Almost seems like when I shut it off there’s a rush of water up the radiator, it hits the cap and then comes out the overflow.

System still runs hot but seems much better than it was. I don’t get the bubbling and gurgling sounds I did with the old radiator.

Do I let it go and see if it continues? Normal? Any possible causes I should look at?

System took about 2.5-2.75 gallons of water. No water in oil that I can see. There was an external crack in the water jacket that I re-repaired with JB Weld that has been there for decades.

[ronn]

well you could still have some blockage in your engine. I always run vinegar in my engines for a few weeks, to clean everything out.
In your case, you could pull your hoses, run a garden hose through the top and see what comes out of your engine at the bottom......... I do that as I run the engine, to get the gunk out.

[psimet]

I ran vinegar through it/ let it sit while I was doing the radiator swap. When I flush it I do it with a hose setup I have that plumbs into the system. While it’s never blocked off to allow the pressure to rise it’s full bore open at the top and restricted to the size of the water outlet on the bottom.

Again the water out the overflow only happens when I stop the engine. It happens immediately when I stop and seems almost like it’s a part of stopping the engine. Almost like the pump stopping causes the current in the water to back up momentarily in the top of the radiator and overflow.

[mcgarrett]

Make sure you don't overfill it above the baffle in the top tank. If you don't have a baffle, keep the level in the tank about half way to the top. Model A's will purge themselves of excess coolant until it's where it should be.

[Rob Doe]

Are you using an infra red temperature gun to estimate the temps you're running at?

The water on our coupe gets 20 degrees hotter after shutdown then starts cooling down. This may be contributing to your problem, but it is normal.

If you have no baffle, you might want the level to be just above the core.

Have you tried a roofing nail in the overflow? I've seen this said to be successful in other posts.

[Jim/GA]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by psimet

<snip>

I’m running water with water wetter. After the first time I looked and the water was just barely over the baffle in the radiator. I know A’s will sort of seek their own level in the radiator. I haven’t checked where the water is now but after that last bit I’d guess it’s just below the baffle or even with it.

<snip>

You may be over filling it. You mention various water positions, relative to the baffle, but not if those are when the engine is hot or cold.

The water should be about 1/2 inch above the bottom of the upper tank (where all the tubes come in) when cold. I use a wooden coffee stir stick as a dip stick to see where the coolant level is when cold because I cannot see it around the baffle.

When hot, the coolant should be right at the baffle with the engine running. Not too much above it.

Having the coolant get really hot and puke out coolant does happen. It's probably a hot spot in the block. A small amount of water turning to steam takes up a lot more space (the steam does) and that makes the coolant level rise. It will go back down.

Let it spit out water on shut down and don't add any more. See where the coolant level is when cold. If there is anything in the upper tank at all, it's good enough. See if the spitting out does not stop then.

[Ernie Vitucci]

Jim...When would you begin to consider a bad head gasket or a crack in the block deck? Ernie in Arizona

[ronn]

well I had to repeat the step of flushing my engine on 3 diff occasions. The last time the mud coming out was horrible!


engine runs cool as a cucumber now.......

[psimet]

Originally Posted by Jim/GA

You may be over filling it. You mention various water positions, relative to the baffle, but not if those are when the engine is hot or cold.

The water should be about 1/2 inch above the bottom of the upper tank (where all the tubes come in) when cold. I use a wooden coffee stir stick as a dip stick to see where the coolant level is when cold because I cannot see it around the baffle.

When hot, the coolant should be right at the baffle with the engine running. Not too much above it.

Having the coolant get really hot and puke out coolant does happen. It's probably a hot spot in the block. A small amount of water turning to steam takes up a lot more space (the steam does) and that makes the coolant level rise. It will go back down.

Let it spit out water on shut down and don't add any more. See where the coolant level is when cold. If there is anything in the upper tank at all, it's good enough. See if the spitting out does not stop then.

Makes sense. Visual levels were when cold. I just checked it when I got home. First time I haven’t been able to see the water - just the baffle. Used your idea for a dipstick and used a twist tie. Using that it looks like the cold level is below the baffle but, As you put it, about 1/2” in to the top tank.

I’ll keep running it and see how it goes from here. Thanks.

[Jim/GA]

Originally Posted by Ernie Vitucci

Jim...When would you begin to consider a bad head gasket or a crack in the block deck? Ernie in Arizona

A bad head gasket or a cracked block will blow coolant out all while driving, plus make the engine overheat, until you are so low on coolant that you are boiling over.

The situation described here sounded more like a lot of coolant expansion on shutdown, possibly some boiling, that will only go so far, then cool down enough to go back down. The coolant puking only goes so far and then settles down to a long-term coolant level that works.