39 Deluxe Coupe Stock Motor Losing Water

[Rooster in a Coupe]

39 Deluxe Ford Coupe Stock Motor Losing Water (Non pressure system)


With a full radiator, there is water loss each time the car is used. Some of the water is blown out due to expansion, however, without topping up, each run thereafter results in more water being blown out. Trips are approx 30mins long and temps range from 100 degrees with full radiator, to 130/140 degrees after 3 or 4 trips and water level is somewhere below the top of the tubes. Have not taken it on any further trips without topping up, as I don't believe that the level should be that low.


There is little or no leaks in the cooling system
Compression and leak down tests OK
No evidence of oil in water
Motor not getting hot, max 140 degrees with water below top of tubes
No Tstats at this stage


Suspect partially blocked radiator. Restricted return through radiator means water pumps building pressure in top tank, causing water to blow out overflow


Intend to remove and clean radiator, flush block and install new hoses and Tstats
Thinking, clean radiator will improve flow, and Tstats will increase operating temp


I could be completely wrong about all of this, so if anyone out there could suggest any reason/cure
your help would be appreciated


Rooster in a Coupe

[40ford]

Level can not be full.It has to get to a "happy" point.Put your tstats in.You need a restriction because your pumping water to fast and it is probably going out the overflow slowly.I have had the same problem before!

[oldskool]

try keeping the level 1 inch above tubes to allow for expansion ,if filled to top it will gust dump it out ,I would also replace the rad cap,you need to run stats also

[Lawrie]

Save your self the worry and pull the radiator,take the top tank off and clean it out,
I put this job off on my 33 for years ,then after taking it out ond cleaning it it now runs as cool as and NO coolant pumping out.
Lawrie

[flatjack9]

Are you running anti-freeze?

[Rooster in a Coupe]

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Yes to the anti Freeze

[Jembow]

I have a similar problem. Motor fully rebuilt, including block flush, new radiator, no stats, runs cool but uses up to half gallon on a 50 mile run. I believe you can get a low-pressure cap for the overflow to stop pumping out and loss by evaporation. Is this the solution?

[Rooster in a Coupe]

I know I need Tstats to increase temperature and slow the flow rate as suggested above.
I'm thinking 77yrs of crud build up causing restriction of flow in radiator and no Tstats to restrict water return to radiator, between these two I'm getting a head of water building in the top tank and what can't get through the radiator takes the next way out which is the overflow
Still open to suggestion, but at this stage going to pull the radiator, install Tstats and new hoses when parts and time permit

Rooster
PS. Its a very original car

[G.M.]

You will never keep the FULL amount of water required for proper
cooling with an open over flow tube. You can modify your filler
neck to take a 4 lb pressure cap or get Skip Haney's 3 lb pressure
valve that go's on the bottom of the over flow tube. With either of
these you can fill the top tank up to the filler neck and it will stay
there for a year as long as the temperature don't get over 200.
More coolant in the system equals better cooling. G.M.

[flatjack9]

Originally Posted by Rooster in a Coupe

39 Deluxe Ford Coupe Stock Motor Losing Water (Non pressure system)


With a full radiator, there is water loss each time the car is used. Some of the water is blown out due to expansion, however, without topping up, each run thereafter results in more water being blown out. Trips are approx 30mins long and temps range from 100 degrees with full radiator, to 130/140 degrees after 3 or 4 trips and water level is somewhere below the top of the tubes. Have not taken it on any further trips without topping up, as I don't believe that the level should be that low.


There is little or no leaks in the cooling system
Compression and leak down tests OK
No evidence of oil in water
Motor not getting hot, max 140 degrees with water below top of tubes
No Tstats at this stage


Suspect partially blocked radiator. Restricted return through radiator means water pumps building pressure in top tank, causing water to blow out overflow


Intend to remove and clean radiator, flush block and install new hoses and Tstats
Thinking, clean radiator will improve flow, and Tstats will increase operating temp


I could be completely wrong about all of this, so if anyone out there could suggest any reason/cure
your help would be appreciated


Rooster in a Coupe

I had that problem with my 39 years ago. I got rid of the anti-freeze and run water with an anti rust additive and have never had a problem in 20 years. Try it.

[G.M.]

I use 2 gallons of full strength Preston perminate anti freeze
in 6 cars in Florida operating in 90 temperature and with 180
Bob Shewman stats they stay at 178 to 182 all the time except
long periods of idle and then gets to 200. At 200 you have to
get moving so the air from forward motion cools the radiator
coolant. It takes about a mile at 30 plus MPH and the temp
starts coming down. Shewman's stats mount up at the radiator
top inlet tubes, have large flow opens allowing more flow. G.M.