| jrbrks | -- 04-19-2026 @ 6:01 AM |
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I have recently purchased a 1941 Ford Super Deluxe. This is my first early Ford V8. The former owner recently had the engine completely rebuilt (approximate 300 miles, since the rebuild). The engine starts easily and quickly, when first starting in the morning. The engine runs smoothly. After running for a short or long period of time and shutting down, the engine will not restart. The engine cranks or turns over adequately, but does not try to fire or start. It just turns over. A second question would be related to the best service manual for this vehicle. I have purchased the "1932-1941 Ford & Mercury Shop Manual" reprint, but I am wondering if there is a more complete service manual option. Finally, the engine is filled with Evans Waterless Coolant. The engine overheats quite rapidly (based on the temperature gauge and use of an IR heat gun). Both sides of the engine record similar temperatures with the IR heat gun. Looking in the radiator, coolant is flowing at a cold start, and the coolant flow rapidly increases when the engine reaches mid temperature on the temperature gauge. I assume the thermostats are opening, but I have not yet pulled the hoses to check their opening temperature. The previous owner had the radiator completely rebuilt/restored. I do plan to flush the waterless coolant and replace with antifreeze/water, but I do not yet know that will fully correct the problem. I do know the waterless coolant has a much lower capacity for heat exchange. I would appreciate any thoughts or advice. Thanks, Jim
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| carcrazy | -- 04-19-2026 @ 7:54 AM |
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The best, most efficient, coolant for you to use depends upon where you live and if your car will experience freezing temperatures! The ideal coolant, provided the temperatures don't dip too low, is distilled water. You will want to use a very small amount "water pump lube" or similar product to prevent cooling system rust and corrosion from occurring. If you have to use any anti-freeze, use the minimum amount to prevent freeze up in the areas where the car will be driven. Check your thermostats to make sure they are functioning correctly. My recommendation would be to use 160 degree thermostats to provide a little more of a "cushion" to keep the temperature of the coolant lower. You never have to worry about Flatheads running to cold! If you have a laser thermometer, you can use it to determine if the radiator is functioning correctly by measuring the temperatures at the top and the bottom of the radiator. A radiator that is working properly will show a difference in temperature between the top and the bottom of 15 degrees F. Hope this helps and that you are able to solve your overheating problem. Remember that it is normal for Flathead fully warmed up running coolant temperature to be about 100 degrees warmer than ambient air temperature.
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| 52flatv8 | -- 04-19-2026 @ 8:50 AM |
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As to the hot restart or not starting, flatheads tend to percolate today's fuels with a negative affect on the carburetor. In some cases causing what some call vapor lock. An electric fuel pump installed near the gas tank can usually help restore fuel & fuel flow. Once running you can turn the elect pump off. You may also have a coil getting too hot and failing. Others here have lots more knowledge on this issue. Make sure your radiator is not over full, you only want coolant just above tubes not up to the top of the tank. Hope this helps. Welcome aboard !
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| carcrazy | -- 04-19-2026 @ 9:33 AM |
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One of the best shop manuals is available from Obsolete Ford Parts. It covers all 1939-48 Ford and Mercury vehicles. The part number is BK-379 https://ford.obsoleteandclassicautoparts.com/catalog/early-ford-v8?qad=44r2qJgN29p3M2yPt3i328v22z3m4Z#page/13
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| pauls39coupe | -- 04-19-2026 @ 7:08 PM |
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Check for a good hot blue/white spark. If you have a fail to start situation after a 5 min to ten minute drive, it is probably the condenser. If it fails after 15 minutes look at the coil. 90% of "vapor Lock " problems are electrical. My bet would be to replace the condenser. They are cheap and easy to change.
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| jrbrks | -- 04-20-2026 @ 4:06 AM |
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Thank you, everyone. I will give these suggestions a try. I appreciate the advice. Jim
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| juergen | -- 04-20-2026 @ 6:50 AM |
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To check for a fuel problem, take off the air cleaner, look down the throat and use the throttle to see if the accelerator pump squirts gas. If not you have a fuel problem.
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| carcrazy | -- 04-20-2026 @ 9:12 AM |
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If the engine cranks over normally after a hot soak but the engine refuses to start, spray some starting fluid into the air cleaner to see if you can get the engine to start and run. If the engine won't even try to start with the starting fluid, the ignition system is not working and you have no spark. The most likely cause is a bad coil that fails when hot. Is the ignition system on your engine completely stock? Does it still have the coil that is mounted to the top of the distributor? This coil uses a resistor that is mounted on the passenger compartment side of the firewall under the driver's side of the instrument panel. This resistor may be failing when hot.
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| kevinshea | -- 04-20-2026 @ 1:00 PM |
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I agree with Pauls39... check your spark, disconnect a spark plug wire and drape it near the block.. DO NOT HOLD IT. .. look to see if you have a nice blue spark jumping a 1/4 gap.. if it is white and weak, it is likely electrical .. check your charging system to see that you are getting full charge out of the generator, then look into your distributor (points/coil/condenser)... also, check your plugs to see of any are fouled as that may point to bad spark also. how long had the car sat after the 300 miles? if these old cars sit for a while, weird things can happen.. corrosion, rust, things get stuck, etc
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| jrbrks | -- 04-24-2026 @ 1:49 PM |
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Another question: Is it possible to drain the coolant from the block of the 1941 Ford V8 by removing the radiator hoses on both sides at the water pump?? The pipe plugs in the block seem very tight, and I do not want to bust off the head. Will the water pump prevent the block from draining? Thank you Jim
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| pauls39coupe | -- 04-24-2026 @ 5:35 PM |
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Yes you can drain the block by removing the lower radiator hoses. Not a fun job if they are old and hard.
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| nelsb01 | -- 04-24-2026 @ 7:44 PM |
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If you have replacement hoses --- a hacksaw can be your friend.
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| marko39 | -- 04-25-2026 @ 4:56 AM |
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is there something wrong with your radiator petcock?
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| RAK402A | -- 04-25-2026 @ 8:34 AM |
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I fought the hard starting when warmed up thing for years. I learned what was causing it from this Skip Haney and this forum. It was a combination of things... 1) Voltage drop from dirty connections-especially the ground straps to the firewall and starter cables. 2) Repro coils-even when brand new, when combined with the voltage drop from the bad connections these had trouble providing enough voltage for a good, blue spark when the car was fully warmed up. Once these items were corrected, the car cranks briskly and will start when fully warmed up with no problem. I live in Southern California, where it gets very hot and it is still not a problem. I take a Dremel tool with a soft wire brush to all the battery connections and grounds every two to three years now. I will only use re-built coils from Skip Haney-no more repros! As others have mentioned, a bad condenser can cause problems too (repro condensers can be bad even when brand new). This message was edited by RAK402A on 4-25-26 @ 8:36 AM
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