Why do you mention muriatic acid? Is that a component of Mr. Clean?

Unfortunately, the '37 Super Eight has an elbow, so you can not see the tubes. In the next couple days I will be able to remove the thermostat from the top tank and inspect those tubes that I can see with a mirror.

Both our '37 Super Eights are manifesting the same problem!
Neither overheats. I have tested the water with thermometers,
but if I drive over 40mph for more than a few minutes, the water bubbles out from under the cap and sprays all over the car.
1. The overflow tubes are clear
2. I have removed the water jacket cover from the block and there is no sediment (on the convertible sedan)
3. I have removed the lower radiator hose...no sediment in the hose or in the bottom of the tank.
4. I have had the water pump on the convertible sedan professionally rebuilt with a ss shaft and permanent seals.(I thought the pump was cavitating and sucking air into the system.

When I restored the LeBaron 20 years ago I had a radiator shop 'process' the radiator....but did not watch to see if they really removed the tanks and cleaned the tubes.

....so now I am looking for relatively easy solution to a very annoying problem.

Pulling a radiator is no easy afternoon job!

I have gotten recommendations to run the engine with
a, vinegar
b, washing soda
c, Mr. Clean

Am open to other recommendations.

I have back flushed the system with 100psi and that does get a lot of gunk out.

Aren't these old cars fun!!!!...but then we can count our blessings that we don't have to be concerned about air bags blowing up in our face!!!!!!

All suggestions are appreciated.

Many thanks for the prompt reply!

Very interesting that Packard had issued that solution!
When was that published?

Guess I will have to fabricate a tub to catch all that water so it doesn't make a mess in the shop.

It is not a trivial job to pull the radiator on a '37 Super Eight (or other similar late '30s Packard.

The 1937 shop manual specifies a 30 gallon per minute gravity flow and the 1937-38 Manual changes the flow to 36 to 41 gallons per minute.

I am curious to know if any reader has devised a creative way to run the test without pulling the radiator.

I have this radiator and don't know what it goes to.
Many years ago I parted out a 1938 Packard 120 hearse.
Would this fit most 120s????

The label says 'McCord B5-88"

Thanks for looking...

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Thanks, everyone, for all the input.
I appreciated it.

Bob

Thanks for all the great input!!!!

Now the $64,000 question......

Why are the base/thread sizes in mm and the gaps in inches???

Bob

The 1937-38 Super Eight Shop Manual specifies using the AC 103S or the Champion Y-4

In my inventory I found an AC 103 but it looks more like one that would be used in a Crosley.

The middle plug is the recommended AC 103S.

Also in the picture is an AC 106, which is a hotter plug and more readily available on the internet, and I

Yes, the local auto parts stores can get Champion 10mm UY6...

Does anyone know if the UY6 has the same characteristics as the 103S or even the 106????

Any answers, comments or suggestions are appreciated.

Thanks.

Bob

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Thanks for all the prompt responses and ideas.
Engine was built 20 years ago.
Since we are retired and travel a lot, our cars sit for extended periods sometime....hard to avoid that situation.

I have heard a lot of folks swear by MMO...and some claim it is just transmission fluid....who knows for sure?!?!...but will heed your advice and report back on results...

Thanks

Bob