The Ford Barn

JanP · 09-16-2016, 04:14 PM

Hi guys,
I think of installing a radiator cap, that keep 7PSI of pressure, because I'm loosing water......
What do you think? Where can I get them from?
Please let me know, what you know about that?

petehoovie · 09-16-2016, 04:32 PM

What is the year of your car? Is the radiator original/stock?

G.M. · 09-17-2016, 09:09 AM

Quote:

Originally Posted by JanP

Hi guys,
I think of installing a radiator cap, that keep 7PSI of pressure, because I'm loosing water......
What do you think? Where can I get them from?
Please let me know, what you know about that?

If your loosing water with a 7 lb cap either the cap is no good
or not seating at the bottom or there is a compression leak. G.M.

V12Bill · 09-17-2016, 10:42 AM

Or you are overfilling the radiator. There should be only enough water to cover the rods by about 3/4"/ If too much water is in the top tank, it will come out the overflow as the water heats and expands.

Bluebell · 09-17-2016, 04:15 PM

Jan P. I have no idea what year radiator you are talking about, but here goes, with my thoughts on a mid 40's era radiator.

My guess is that it depends on what your radiator was built for. Here is a snippet on Canadian Ford military radiators.
Early in WWII they were not pressurised
With the introduction of a 3.5 lb pressure valve in (Bren carriers and likely trucks, brought on by the need for a closed system in the North African desert) they found that the seams in the tanks were letting go, so they modified the components in production to have wider laps (for the soldered seams)
Radiators of that era were well made of relative heavy materials, but the top tank design does not lend its self to high pressure, in my opinion.

I think that if you have a radiator that wasn't made for a pressure system, that you are going to split seams and crack top tanks etc. If you have a rad that was built to be pressurised, that it is probably still only good for a 4 lb system.

From an open system to a 4 pound pressure system raises the boiling point of the system about 3 1/2 degrees per lb, About 14 degrees F. at sea level, from 212 to 226 F. which is significant if you think about it.

G.M. · 09-18-2016, 08:25 AM

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4 lbs pressure is not going to hurt a radiator in reasonably good condition.
Skip has been selling a 3.5 lb pressure valve that is fitted to the bottom of
the over flow tube on early radiators that were not made for pressure caps.
Raising the boiling temperature has nothing to do with making the early
Ford radiators pressurized. The flow in these radiators is restricted by the
length and the 144 tubes causing the water to back up in the top tank and
then is lost out the overflow tube. The answer is not less water in the
radiator which causes the engine to run hotter. The solution is a pressure
cap with a low operating pressure that keeps ALL of the water in the
radiator AND also act a safety valve to release pressures over 3.5 in the
case of Skips valve or 4 lbs on the early Ford pressure caps. An engine
running under 212 degrees will have less than 3.5 lbs and no water will
be added for over a year. Another problem is most old Ford engines have
some slight internal water leak, a bottle of Barr's heavy duty stop leak
in almost all cases stop this leakage. One indication of a leak is water
out the exhaust at start up or air bubbles in the radiator. There may be
a little from condensation for a few minutes but if it continues it is a leak.
Even water pumps can have a pin hole casting leak or a slight crack on
the 32 to 36 pumps from a freeze up. These cracks are hairline and
usually on the curve right behind the pulley and can be welded. G.M.

09-16-2016, 04:14 PM	#1
JanP Member Join Date: Dec 2014 Location: Hamburg, Germany Posts: 30	radiator cap Hi guys, I think of installing a radiator cap, that keep 7PSI of pressure, because I'm loosing water...... What do you think? Where can I get them from? Please let me know, what you know about that?

09-16-2016, 04:32 PM	#2
petehoovie Senior Member Join Date: May 2015 Posts: 8,111	Re: radiator cap What is the year of your car? Is the radiator original/stock? __________________ The only thing nice about being imperfect is the joy it brings to others.... *"Silver rings, your butt! Them's washers!"* "We shot our way out of that town for a dollar's worth of steel holes!" - from 'The Wild Bunch' - 1969 https://www.youtube.com/watch?v=7NReUd2_0u0

09-17-2016, 10:42 AM	#4
V12Bill Senior Member Join Date: May 2010 Location: Mt. Holly,NJ Posts: 1,822	Re: radiator cap Or you are overfilling the radiator. There should be only enough water to cover the rods by about 3/4"/ If too much water is in the top tank, it will come out the overflow as the water heats and expands.

09-17-2016, 04:15 PM	#5
Bluebell Senior Member Join Date: Nov 2012 Location: Tauranga, New Zealand Posts: 726	Re: radiator cap Jan P. I have no idea what year radiator you are talking about, but here goes, with my thoughts on a mid 40's era radiator. My guess is that it depends on what your radiator was built for. Here is a snippet on Canadian Ford military radiators. Early in WWII they were not pressurised With the introduction of a 3.5 lb pressure valve in (Bren carriers and likely trucks, brought on by the need for a closed system in the North African desert) they found that the seams in the tanks were letting go, so they modified the components in production to have wider laps (for the soldered seams) Radiators of that era were well made of relative heavy materials, but the top tank design does not lend its self to high pressure, in my opinion. I think that if you have a radiator that wasn't made for a pressure system, that you are going to split seams and crack top tanks etc. If you have a rad that was built to be pressurised, that it is probably still only good for a 4 lb system. From an open system to a 4 pound pressure system raises the boiling point of the system about 3 1/2 degrees per lb, About 14 degrees F. at sea level, from 212 to 226 F. which is significant if you think about it.

09-18-2016, 08:25 AM	#6
G.M. Senior Member Join Date: May 2010 Location: Florida and Penna. Posts: 4,471	Re: radiator cap Sponsored Links (Register now to hide all advertisements) 4 lbs pressure is not going to hurt a radiator in reasonably good condition. Skip has been selling a 3.5 lb pressure valve that is fitted to the bottom of the over flow tube on early radiators that were not made for pressure caps. Raising the boiling temperature has nothing to do with making the early Ford radiators pressurized. The flow in these radiators is restricted by the length and the 144 tubes causing the water to back up in the top tank and then is lost out the overflow tube. The answer is not less water in the radiator which causes the engine to run hotter. The solution is a pressure cap with a low operating pressure that keeps ALL of the water in the radiator AND also act a safety valve to release pressures over 3.5 in the case of Skips valve or 4 lbs on the early Ford pressure caps. An engine running under 212 degrees will have less than 3.5 lbs and no water will be added for over a year. Another problem is most old Ford engines have some slight internal water leak, a bottle of Barr's heavy duty stop leak in almost all cases stop this leakage. One indication of a leak is water out the exhaust at start up or air bubbles in the radiator. There may be a little from condensation for a few minutes but if it continues it is a leak. Even water pumps can have a pin hole casting leak or a slight crack on the 32 to 36 pumps from a freeze up. These cracks are hairline and usually on the curve right behind the pulley and can be welded. G.M. __________________ www.fordcollector.com