V8 Flathead Overheating
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V8 Flathead Overheating
I have restored a '48 F-1 and still have a lingering problem with engine overheating. I had the radiator recored a few years ago, however the truck doesn't get much running time. Can anyone tell me how long it takes for the radiator to go to rust when dormant. Any ideas on cooling would be appreciated.
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Joined: Jun 1999
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V8 Flathead Overheating
For the radiator, if you did recore,not just rod out,you can rule out the radiator if the problem has existed since then.For long term storage,if the mixture still tests good,that shouldn't be a problem either.You will want to the check basics before you tear in to it.What about the radiator cap? Have it checked for leakage and proper engagement on the neck.Look at the fan blade and make sure it is pulling air through the radiator,not pushing,which you may find a blade mounted upside down(boy,wouldn't that be easy).Next you'll want to check the thermostat(s) in a pot of water as you bring it to a boil and noticeing the thermometer readings when the t-stat begins to open & no longer opens further(if it ever gets there).Next,verify the gauge reading(if any) and location.A mechanical gauge pellet that is inserted in a position that will allow near contact with engine metal will show higher than coolant temps.Now the water pumps, i don't think you can mix the left & right pumps,but what if one of the impellers is rotted away?post more info as you have it.
Phillip
Phillip
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Joined: Aug 2001
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V8 Flathead Overheating
Replace the thermostats rebuild the water pumps and flush the block with the pumps off ( the original casting sand may still be in the block as they really had no way to get it all out ( heard of a block being dripped in a tank for cleaning and they got a quart of sand out )) good luck and I see that it has been a while since this post so I hope that you already solved the problem
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Joined: Nov 2001
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V8 Flathead Overheating
I had a 50 that over heated do I put on a 6 bladed flex fan. I also pulled the heads and found foundry wires inside the water passages in the block. They are used to hold the cores together when the iron is poured. It never did run cool, always at 3/4 on the gage.If you put on a shroud it will really help.)
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Joined: Sep 2001
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V8 Flathead Overheating
I don't know anything about the flathead V8, but I do have a 49 COE with a flathead. If anyone is in need let me know. The truck running gear is complete, motor runs and tranny and 2-speed rear axel work. I bought it just for the cab. I am in southwestern Missouri. 67stang@centurytel.net 
Mountain Pass
Joined: Aug 2000
Posts: 139
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From: Marshall TX
V8 Flathead Overheating
This may sound crazy... but I discussed overheating with a flathead guru of over 50 years experience. He said lots of "flatheaders" have sawed off every other tooth on the water pump impellers. He claims if the pumps are really effective, they will pump the water through the radiator faster than it has time to be cooled in the radiator. He claims that every time that has been done it works.
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Lead Driver
Joined: Oct 1999
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From: Kalispell, MT
V8 Flathead Overheating
I've heard about guys removing waterpump vanes also, but only on the early V8's that are open systems without thermostats or other restrictors. On 48 and up truck motors it shouldn't be necessary - that's what thermostats do.
I had an overheating problem that developed recently. I couldn't keep coolant in the system. Pulling the thermostats allowed me to get home, but I kept having to add coolant. I pulled the heads and found a cracked block on cylinder #6 into the intake valve. A compression check showed that cylinder to have zero to 10 psi.
I'd check compression first to see if something major is going on inside the engine.
Then check timing, fuel settings, etc.
These trucks were built with oversize radiators and should be more than adequate for the type of driving you're doing. Keep looking for something else that's causing you to overheat. Think about the symptoms you have and a pattern will develop. There has to be a reason. Good luck. Tim
I had an overheating problem that developed recently. I couldn't keep coolant in the system. Pulling the thermostats allowed me to get home, but I kept having to add coolant. I pulled the heads and found a cracked block on cylinder #6 into the intake valve. A compression check showed that cylinder to have zero to 10 psi.
I'd check compression first to see if something major is going on inside the engine.
Then check timing, fuel settings, etc.
These trucks were built with oversize radiators and should be more than adequate for the type of driving you're doing. Keep looking for something else that's causing you to overheat. Think about the symptoms you have and a pattern will develop. There has to be a reason. Good luck. Tim
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From: Walla Walla USA
V8 Flathead Overheating
I have a 48 flathead 6 that overheated. Not too sure on the 8 flathead but the exhaust manifold has a butterfly that opens and closes. It was designed to stay close while the engine was warming up (Detroit winters) and then open once the engine warmed. My butterfly was stuck / broken etc. I just had to do away with it and my overheating problems went away. I also did all the usual things but to no avail until I looked into this. Check out my 48 site
http://www.48f-1.com
jim
http://www.48f-1.com
jim
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V8 Flathead Overheating
>I have a 48 flathead 6 that overheated. Not too sure on the
>8 flathead but the exhaust manifold has a butterfly that
>opens and closes. It was designed to stay close while the
>engine was warming up (Detroit winters) and then open once
>the engine warmed. My butterfly was stuck / broken etc. I
>just had to do away with it and my overheating problems went
>away. I also did all the usual things but to no avail until
>I looked into this. Check out my 48 site
>http://www.48f-1.com
>jim
>8 flathead but the exhaust manifold has a butterfly that
>opens and closes. It was designed to stay close while the
>engine was warming up (Detroit winters) and then open once
>the engine warmed. My butterfly was stuck / broken etc. I
>just had to do away with it and my overheating problems went
>away. I also did all the usual things but to no avail until
>I looked into this. Check out my 48 site
>http://www.48f-1.com
>jim
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