| tpls46ford | -- 06-25-2025 @ 1:13 PM |
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Have a 1946 Ford super deluxe convertible that seems to run hot. 155-160 degrees. Replaced both thermostats with new 160's. Drilled 2 holes in each one at 12 oclock and one at 6 on each thermostat. Still running hot. Waiting on a new radiator cap. 4lbs. When the car is running and the radiator cap is off I can't see any flow of water in the radiator. The radiator looks in good shape. No leaks or damaged coils. Was going to replace the water pumps next. Any thoughts or ideas out there? tom tom
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| nelsb01 | -- 06-25-2025 @ 1:24 PM |
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Guess we need to ask how you know you are running hot at 160? I would pray for 160. I just drove my 1949 Ford to Springfield for the 2025 Central National Meet and every time I stopped I opened the hood and used the thermal temp gun to check the head temps --- 203 drivers side, 204 passenger side, top of radiator 187. You need to increase your idle to see water flow in the radiator top tank. Using a cooking thermometer (dont tell the wife) in your radiator will give you a much better feel for your engine temperature.
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| tpls46ford | -- 06-25-2025 @ 1:41 PM |
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Didn't tell the wife I used her meat thermometer. LOL Put the probe on the block and got the 160 reading. Ill check the flow in the radiator while accelerating. tom
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| tpls46ford | -- 06-25-2025 @ 1:43 PM |
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used the wifes meat thermometer. Put the probe on the block and got 160. Ill check the flow in the radiator while accelerating the engine. thanks tom
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| carcrazy | -- 06-25-2025 @ 2:55 PM |
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Your Flathead Ford is not running hot! My rule of thumb for Flathead engine temperatures is that the water temperature will be about 100 degrees F hotter than the ambient air temperature. Applying this guide to the actual water temperatures, if the outside air temperature is 100 degrees, your coolant temperature will be about 200 degrees F. Of course the coolant temperatures will rise above this if you are accelerating or climbing a hill.
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| 40 Coupe | -- 06-26-2025 @ 4:02 AM |
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I agree with the above posts. The water in the radiator should just cover the core. Too much water and it will come out of the overflow. Pressure caps on the radiator will cause the upper tank to bulge over time. Since you do not appear to have a problem suggest keep the original style radiator cap.
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| juergen | -- 06-26-2025 @ 5:40 AM |
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On my car, the (pressure) cap does not cover the overflow tube. I used a 3 pound pressure tube cap made by Skips to "seal" it and added a 3 pound pressure cap. This eliminated the loss of coolant while traveling at speed as the radiator didn't flow as fast as the water pumps would supply. I was told not to use a larger pressure cap as it would cause the upper tank to flex.
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| 51woodie | -- 06-27-2025 @ 5:38 AM |
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When I bought my '46 Coupe, stock 59AB and rad, it had miss matched stats (160/180) and one was cocked 45deg in the hose. Reading posts about overheating , I installed new 160s, new style pumps, a 4psi cap, and had a rad shop "descale" and pressure test the rad. After a few trips, I replaced the 160s with 180s as the engine ran to cold for my liking. One thing that I believe helps with cooling is that it has a six blade fan, which may not be what came out of the factory. In talking with others, some causes of overheating, other than those listed in above responses, is missing top or bottom shrouds and or shroud seals. Recently did a three hour run in 80deg at 65-70 mph, and temp held at 180deg. with stock gauge sitting at mid point. City/town driving might get the temp to 185deg. Temp shows lower than actual reading due to camera angle. This message was edited by 51woodie on 6-27-25 @ 5:40 AM
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| tpls46ford | -- 07-03-2025 @ 2:15 PM |
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Well I replaced the thermostats, water pumps and a new radiator with a 4 lb cap on my 46 ford convertible flathead V8. Still running hot. 210 degrees. When the4 vehicle is running and I squeeze the hoses going into the radiator I really cant feel water in them. I can get a few air bubbles at the top of the radiator. The only thing i can think of is maybe the thermostats are in backwards? They are 160 and I drilled 2 small holes in them as shown on a diagram. Any thoughts? tom tom
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| tpls46ford | -- 07-03-2025 @ 3:00 PM |
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pulled 1 of the hoses that thermostat was in and they were in correctly. The new radiator had 1 1/4" outlet in the top. The original radiator had a 1 3/4" outlets on the top. I stepped the original 1 3/4" hose down to 1 1/4" using a metal sleeve to attach them together and attached to the top outlets of the new radiator. Could that be an issue? Any thoughts appreciated. thanks tom
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| pauls39coupe | -- 07-03-2025 @ 6:06 PM |
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Try taking the thermostats out, they may be bad. Are the lower hoses solid or do they collapse with the engine running. What is the temperature of the lower hoses compared to the temp of the water going through the upper hose? If you are getting air bubbles or exhaust bubbles in the radiator? Remove the fan belt and run the engine briefly. If you are seeing bubbles you may have a blown head gasket our a cracked block or head.
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| carcrazy | -- 07-03-2025 @ 8:36 PM |
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Tom, Here are several questions to answer in trying to find out why your coolant temperature is 210 degrees F. What is the outside ambient temperature when you measure coolant at 210? What radiator are you using? Is it made of the same material as the stock radiator? Does it have the same capacity? Has the radiator been painted with a thick coat of paint? Does it have the same number of tubes and fins per inch as stock? How are you measuring the coolant temperature?
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| tpls46ford | -- 07-04-2025 @ 6:55 AM |
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Went and purchased a infrared thermometer and will be checking the temps in several areas today. Including the sensor on the block. My radiator is a new Champion aluminum with 3 cores. I did not paint it. The new water pumps are not leaking at all and are turning when the engine is running. When I put the new thermostats in I put them in the hoses as far as where the hose goes from 1 3/4" to the smaller size. Was thinking maybe I might have them to far up the hose? Maybe I should have placed the thermostats on the block first and then push the hoses on to the thermostats? Really appreciate the feedback!!! Thanks tom tom
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| tpls46ford | -- 07-04-2025 @ 1:31 PM |
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removed the front shroud in front of the radiator and the car ran cooler. 180 degrees while running on the street. however heated up 220 when idling in a stationary position. Used an infrared temp gun. Was thinking perhaps of a electric fan. has anyone installed an electric fan in a 46 flat head? how difficult was this? tom
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| carcrazy | -- 07-04-2025 @ 5:14 PM |
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Hi Tom, I installed an electric fan on a 1937 Ford V8-60 radiator with the radiator out of the car. This was not too difficult of an installation. One place to obtain a good fan from is Fifth Avenue Internet Garage. https://www.fifthaveinternetgarage.com/
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| carcrazy | -- 07-04-2025 @ 8:02 PM |
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This is the 14" diameter fan that I installed on the V8-60 radiator. Electric fans from Fifth Avenue are available as either 6V or 12V units.
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| Drbrown | -- 07-08-2025 @ 7:42 AM |
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MY thoughts ...... RADIATOR: When cold, coolant level in neck of radiator should be about 2 inches below top of neck. Provided the radiator fins are clean and clear this should allow adequate space for expanded coolant. THERMOSTAT PLACEMENT: I bought a short piece of rubber radiator hose at NAPA that fits just inside the hose going from top of head to radiator. Cut two - one inch lengths, put inside both hoses, pressed onto head outlet to position it, then remove the whole and glued the inserts in place with rubber glue. This keeps the stats in position. Drilling smal hole in stats does encourage minimum flow so the stat functions sooner. TEMP: My '47 runs at about 160 deg without thermostates on a 70 deg day. Tried 185 stats but it would start to run hot if standing in traffic on a hot summer day. Presently have 165 deg stats and works fine and I avoid traffic jams. Note that right and left side of block do not generate same amount of heat due to block casting differences. If a heater hose is tapped off one side (usually passenger side) it will also present differences. STOCK FAN'S: Too much space between fan blades and opposing face of radiator encourages over-heating because the fan is not sucking enough air THRU the radiator i.e. when car standing still, the fan is just thrashing air AROUND in the engine compartment around. Shim as required but leave at least one inch clearance. Note that there are Truck fan blades that have six blades - but hard to find. ELEC FANS: I tried an electric fan once. Had to increase my alternator size to feed it. Was not satisfied with performance so removed it. This message was edited by Drbrown on 7-8-25 @ 7:59 AM
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| carcrazy | -- 07-08-2025 @ 8:00 AM |
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If you are willing to convert to a 12V electrical system and use an alternator that has an output of at least 60 amps, you shouldn't have any problem powering the cooling fan.
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| tpls46ford | -- 07-08-2025 @ 2:39 PM |
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got the fan and some mounting hdw. Got it from speedway motors. Its designed to mount either outside on inside of the radiator. My thought is to mount it outside of the radiator. When it is on it would be blowing air into the radiator core. I know it will need modify brackets to install. I should be able to figure out mounting it. Supposed to fit in 46-48's Should have by friday tom
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| tpls46ford | -- 07-08-2025 @ 2:42 PM |
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going to leave the existing 4 blade on as well tom
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| carcrazy | -- 07-08-2025 @ 3:56 PM |
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For maximum cooling efficiency the electric cooling fan should be mounted so it pulls the air through the radiator. Fans mounted in front of the radiator will block the airflow passing through the radiator. If your electric cooling fan is of adequate capacity and efficiency to cool the engine, you won't need to keep the engine mounted mechanically driven fan.
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| tpls46ford | -- 07-09-2025 @ 7:17 AM |
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Thanks for the information!!! tom
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| tpls46ford | -- 07-09-2025 @ 7:31 AM |
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did you add an additional shroud to the new fan assembly? tom
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| carcrazy | -- 07-09-2025 @ 12:04 PM |
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Hi Tom, I did not ad an additional shroud around the cooling fan assembly. My advice would be to install the the cooling fan on the upper third of the radiator where the coolant coming into the radiator is hottest. Once you have the fan installed and working, drive the car to determine if the engine is running cool and not overheating. If the engine still overheats, install cooling shroud(s) as required to force the air to flow through the radiator. Also you can install rubber seals (can be made from old inner tubes) around the outer edges of the front of the radiator to get the maximum amount of air to flow through it.
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| tpls46ford | -- 07-09-2025 @ 12:20 PM |
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Thanks! I'll proceed that way. tom
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| Drbrown | -- 07-12-2025 @ 7:24 AM |
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I have not used it but my '47 came with a home-made circular shroud made of sheet metal and rubber that gets mounted on the engine side of the radiator and forms a circle around the fan. Four bent steel angles attach it to the radiator frame. It has a rubber strip around the edge that seals the shroud against the radiator. The shroud forces the fan to suck air thru the radiator, greatly increasing the fan's effectiveness.
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