Never an issue with my 52.  Don't drive it all that much but have on some pretty hot days.

Hallo all!
My P 23 had got a new radiator core 20 years ago.
Only once in Italy, 60 mph allowed on a highway into the Appenine Mountains,
temperature around 32 deg. C / 95 F, but in the numerous and long Tunnels temperature
rose to over 40 C / 110 F !
The water went up to max (ca. 98 deg. C / 208 F), so I preferred to put in a stop letting the engine idle a while.
Temp immediately dropped to normal.
Later, I put a hefty (12 V driven) fan on the radiator.
Only 2 or three times I was very happy to have it on hand!
In the 17 km ( 10,5 mls) long St. Gotthard -Tunnel I sometimes had this situation too.
Always in the southern half of Gotthard (btw.: my full name, Godehard, comes from this mountains titular saint:
St. Gotthard!), the temp is much higher than in the northern half.
It is 1- lane only for each direction, restricted speed and very intensive traffic.
Even in these extreme situations, the cooling did not fail.
The water tube was new than and I had 4 additional temp. gauges in the car:
air temp, water temp, double ice box innerand outer box temp.
The inner ice box  ( a thermos bottle) was needed to keep a medicine for my late first wife
without fail under 8 deg. C / 46 F point. The outer was a Coke cooler.

[attachment id=0 msg=18971]

Starting with minus 18 deg. C  / 0 F ice fillings in Düsseldorf, the inner held that with
ease 24 hrs!
  I had to keep an eye on all these parameters in those years!

Greetings from Düsseldorf!
Go

My 55 Plymouth has never overheated, I've owned it since 1978. I did have a problem when I drove it at hight speeds for awhile the temp guage went up but never ovrheated. Problem solved I had the radiator recored. Now the temp guage goes up to around  1/4 and stays there. I live in Florida so the car knows what HOT is.

I drove my 30-U daily from 1962 until 1972 and it never overheated.  In fact, I often needed to block off a part of the radiator to get it up to operating temperature in cooler weather as it usually ran around 160 degrees.  I am talking about stop and go traffic in the heat of the summer and I don't even have a water pump.  I also have a number of Model T Fords and they also run cool even in Florida heat.  Same is true of the flat head Ford V8.  If they overheat it's because the radiator is no longer performing as intended and/or the water pumps have not been been serviced.  I worked on those flat head V8's when I was a kid and owners who knew their cars had the radiator flushed and water pumps taken down and serviced every spring.  I hated doing it but they never overheated.  It is true that Ford engineered their cooling systems without a lot of extra cooling ability but it was certainly adequate for a properly maintained system.

I have heard about the water distribution tube made our of thin steel (inside the block) getting rusty and collapsing or plugging causing over-heating.

http://www.plymouthcarclub.com/2015/10/coolantdistribution/

http://p15-d24.com/topic/32716-the-sword-in-the-stone-a-water-distribution-tube-adventure/

https://www.robertsmotorparts.com/water-distribution-tube-short-6-cyl-engine-works-with-201-218-230-1

I've had our '32 cabriolet for 20 years. I run it all summer and have had it on may tours including 5 Glidden tours. It's four banger has never overheated and has been a very reliable car.

It was mentioned this morning on the FB POC page that the old flat heads were noted for overheating or running hot.  I know that Henry's flat head had that problem darn near up the end in 1953, but I have to ask about the Plymouth flat heads.  I have had my car for thirty years this fall, the engine that was in it was a P11, which eventually gave up the ghost about ten years ago, but she never overheated once, then I put in a stop gap 1936 Plymouth engine that was worn out also, but worked for me for three or four years until I could find a good rebuilt engine, which I did, and I want to also so that the '36 engine didn't overheat either.  Just wondering if I was lucky and what others think that are older than me (70) and remember these cars when they were in everyday use.  I do drive my car approx. 2500 miles each year and I live in the Catskill Mts of NY for there is some steep climbing that is done