Lately I've noticed a noise coming from the heater core. Best I can describe it is a low gurgling/rumbling type noise... hard to say. It's not the fan motor, did the same thing with the motor unplugged. It doesn''t seem to change with engine rpm. It stops maybe a second after switching the motor off.

Both hoses are burn yourself hot to the touch after running up to operating temp. When it cools off, the (smaller?) hose going to the head is hotter. I would think this is normal since this is the higher hose in the engine and hot water rises....

Any thoughts? could the core be plugged enough to make a noise but not enough to stop all flow? The engine comes up to temp normally and I don't notice any crud rust etc in the radiator when pulling the cap. Looks as clean as the day I filled it.

How many leafs and other debris is blocking flow in the heater box?

Sounds like could have some air in the line and some steam trapped in the heater core. Check your over flow hose and cap to make sure the radiator is full to the top when cooled down. Before you start it up from an over night cooling off period the radiator should be completely full the next morning. If it is not full, check the over flow hose and tighten the clamps. Tighten all the other hoses and make sure both gaskets on the radiator cap are good.

The system can act up when living in a warm climate, running a 195 degree stat and a old 16 lb cap with a few cracked or leaky hoses. I make sure my coolant recovery system is working spot on and everything is good and tight.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Wow, didn't realize this was over a month old already.

I don't have any crud in the heater box - years back I took a piece of stainless steel window screen and weaved it through the cowell grill. I got tired of having to clean out the drains.

I have a catch can but I run the radiator with about 1/2 of the top tank full, can't remember exactly why I justified that last time I fussed with the coolant. That was some time ago, so I decided to do a mini overhaul of the cooling system. Got a new cap (stant, 16lb), new thermostat (stant superstat 195) and change out the coolant (Zerex G-05 50/50) to the top. So far no more strange noise, but it was an on again off again thing.

Been chasing a few leaks that sprung up. Seems they have been exposed since there is more pressure in the system because there is no expansion room in the top tank. At this point I'm stuck at the filler neck. The upper seal in the cap isn't sealing. The neck on my rad is thin and easy to tweak, but I still couldn't get it perfect. What do you think about running a bead of silver solder around the neck and filing it flat?

I'm suspecting the cap itself as well. The upper seal doesn't contact the main body of the cap, so its relatively easily pushed back by a finger. I thought of putting an o-ring behind it so it doesn't get pushed up. Or is there a better brand/style cap that has a firmer upper seal?

Or maybe when the neck is fixed I won't have to worry about the cap. You would figure since there is no pressure in the overflow tube that it should be sufficient enough... hmm. Perhaps 16lb is too much for that skinny a tube. The neck seems pretty fragile and thin, I wonder if the cap distorted the neck to begin with.

I had that problem on my new radiator.....not being flat but I was able to square it up with several different bent needle nose pliers. It too was very soft copper.
That is a good idea to soldier it and file it flat. That should help stiffen it a little.
I had tried many new caps and they all leaked so once I got the surface flat, all was well.
It holds fine with a 16lb. cap.

Good luck on yours!

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

My 72 Duster always made that gurgling noise in the heater core. It never presented a problem. It was weird, I suppose, but it never leaked. And, it always provided good heat, for 13 years.

SAm

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