Topic: Radiator Cap


louganser    -- 10-25-2011 @ 10:59 AM
  Living in the mtns. of western NC my
'47 runs hot when the weather is hot and driving in the mtns. The engine doesn't overheat but I was loosing coolant. Rad has been redone, installed 2 new water pumps and timing is OK. I installed a coolant recovery tank on the OS of the fender well under the RF fender. When hot, coolant goes into the tank but does not return. I've been told I need a pressurized cap to allow the coolant to return to the rad. Where can I find same? Thanks!

Lou G


alanwoodieman    -- 10-25-2011 @ 1:11 PM
  Lou, does your radiator still have the vent on the top of the tank? If so you can buy a 3 lb pressure releif valve to go on the bottom of this tubing, if yours has the service replacement type of radiator you can purchase the 4 lb cap from just about any auto parts store-Carquest has one #33018 which may be a 7 lb cap but they can work back to a 4 lb from that number. Get your flatty out and come to Greenville Nov 4th to the hot dog lunch at Earley Ford Parts
Alan G


supereal    -- 10-25-2011 @ 3:15 PM
  Lou: When the radiator loses coolant, does it only go out until the core is just covered? If the radiator is filled to the top, it is normal for coolant to be forced out by expansion as it gets hot. My '47 has always been that way, even with a 4# cap. Sierra antifreeze helps, as does just running with water and some anti rust stuff. Mountain driving is tough, given the need for power, and a lower atmospheric pressure.


Old Henry    -- 10-25-2011 @ 10:35 PM
  I live in Utah and do a lot of mountain driving. Even drove to the top of Pike's Peak this summer. (Story here: http://www.fordbarn.com/forum/showthread.php?t=19141&highlight=pike%27s+peak)

What I learned long ago is that the stock cooling system is not designed to be completely full of water. If you completely fill it, then when it heats up and the water expands, it's got to blow out of the cap. That's OK. It doesn't need to be clear full. Mine never is. It has naturally got to have an "air cushion" of 2 inches at the top of the radiator to allow for the water to expand. Doesn't hurt anything. That's how it's made to work. So, if you don't try to keep the system completely full (like modern systems do with a coolant recovery tank) but just let the water blow out after you completely fill it and not worry about refilling it back up to the top, you should be just fine.

If you do want to try the modern "recovery tank" method of keeping it clear full, you have to have a special cap that lets the water go both ways - in and out - to get the cooling system to suck the water back in after it's blown some past the cap into the recovery tank when expanded. Here are some gadgets that claim to work. I've not tried them so don't know. You might want to check them out.
http://macsautoparts.com/search.asp?sb=0&ls=y&camid=F30&year=1947&make=Ford&ss=radiator+overflow+tank&x=12&y=13

Old Henry
(The older I get, the better old looks.)


37RAGTOPMAN    -- 10-26-2011 @ 5:38 AM
  try adding coolant at operating temp or close to it,
watch you gauge and feel the temp,
this way the system is filled,then install the rad cap,
this is what you supposed to do.not cold,
it will always spill out if you do it cold,,,,
I have used Skips valve,[ here we go again] with great success, going over the NH, VERMONT, and NY, STATE montains, with no coolant loss,and hold pressure for months,
you might want to try one of these,
what do you have to loose ???
my 3 cents 37RAGTOPMAN

This message was edited by 37RAGTOPMAN on 10-27-11 @ 6:01 PM


supereal    -- 10-26-2011 @ 7:17 AM
  Coolant recovery bottles must be open to the atmosphere. They require a radiator cap designed for the purpose to allow the coolant to be drawn back into the radiator as it cools. Generally, if you lose coolant regularly, you are overfilling the system, or have some other problem, such as a leaky head gasket or block crack. I've owned my '47convertible for twenty years, and never needed a recovery bottle set up. A partially blocked radiator will allow the water pumps to crowd the top tank, pushing out coolant as heat and speed rises.


EFV-8 Club Forum : https://www.earlyfordv8.org/forum
Topic: https://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=3887