| Andy0812 | -- 10-21-2009 @ 2:52 PM |
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My 51 Flathead keeps overheating/running hot. It back fires once it starts to overheat. This happens when you let off the gas. Changed thermostats,checked radiator. Have electric fan which is running correctly. Running with distilled water and water pump lube. (helped a little) Other than that it runs perfectly. All of a sudden it just started overheating.
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| 47Fordor | -- 10-21-2009 @ 3:25 PM |
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Ok, I have a stupid question: is the radiator boiling over or are you going by the gauge? If it's boiling over, and you say you changed the thermostat, look in the radiator, with engine running, and see if the water is circulating. You may have a bad pump. If the gauge is reading hot but the radiator isn't blowing steam, you may have a bad gauge or sending unit. There certainly are a lot of guys on this site that know more about these old beasts than I but my limited experience says that if there's water in the cooling system and it's circulating, the engine should stay cool. The reason for my stupid question: my Dad bought a used '48 in 1955, to go to college. After a few years, he started having problems. He'd be driving along and, for no aparent reason, the oil pressure would drop to nothing. Well, after a new oil pump, new main seals and bearings and much frustration, he finally stuck it in a barn. About twenty years later, we pulled it out and cleaned it up but soon it was at it's old tricks. Dad took it to an old mechanic in town that was really good. It turns out that the problem was the oil pressure sending unit! Who'da thunk it??? Chris
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| ford38v8 | -- 10-21-2009 @ 9:16 PM |
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Andy, check your pump belt. It may be glazed, slipping on the pump pulleys. An electric fan on a flat Ford is seldom the answer to an overheating problem, and can actually contribute to the problem, as the 6V generator has to work harder to supply juice for it. Alan
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| Chevguy49Ford | -- 10-22-2009 @ 5:06 AM |
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When you say you are running distilled water and wp lube, are you not mixing that with antifreeze as well? Antifreeze will not only protect the engine from freezing but it has a higher boiling point and much better cooling properties than just water. If you are mixing it then disregard my bs, but if you are not it will likely cure or at least greatly improve your heating problem. Cheers, Scott. 1949 Custom Tudor. http://i36.photobucket.com/albums/e42/35thLE/49016.jpg
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| Andy0812 | -- 10-22-2009 @ 5:58 AM |
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Thanks for thhe info. Definitely not the gauge. It is boiling over. I'll check circulation
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| Andy0812 | -- 10-22-2009 @ 6:00 AM |
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If it helps I converted to a 6v alternator. But it was overheating before that. Nothing has changed and it just started boiling over or running hot.
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| Andy0812 | -- 10-22-2009 @ 6:06 AM |
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After I drained the antifreeze added only water it did run cooler. For what it is worth I was told that water is much better a disapating heat than anti-freeze and it did run somewhat cooler. At the time when it was explained to me it made sense.
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| trjford8 | -- 10-22-2009 @ 6:44 AM |
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Andy, how old is the coil and condensor? The backfiring may be a sign of a bad condensor. Had a similiar problem with a '38 I once owned. After installing a new coil and condensor it ran cooler. I would also recomend a set of Skip's water pumps.
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| Chevguy49Ford | -- 10-22-2009 @ 9:45 AM |
quote: I will agree with you that if the old coolant you drained out was past the end of its life, and full or rust, mud etc, then straight water will definitely work better. You also could be right that plain water will transfer heat better, I don't know that for sure. What I do know for sure though is that the coolant you mix into the water raises the boiling point of the water, along with adding anti-corrosion and lubricating properties. That being said, it is not at all abnormal for a cooling system running straight water (which boils at 100°C) to boil over, since the normal operating temp can range from about 180° to 220°. The fact that the system is under pressure will raise the boiling poiint of the water some, but not enough to keep it from boiling when it gets too hot. Even if you are in a climiate where you don't need the freeze protection from antifreeze you should still run it to keep the cooling system in good shape and to keep the water from boiling. I would not be surprised if this cures your problem. Always look for the simplest solution first. Cheers, Scott. 1949 Custom Tudor. http://i36.photobucket.com/albums/e42/35thLE/49016.jpg
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| supereal | -- 10-22-2009 @ 10:01 AM |
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Antifreeze does not cool better than plain water. In unpressurized systems, such as the Model A. it will usually result in loss of coolant around the radiator cap and/or the overflow. Thus, the addition of the pressure cap on later vehicles which raises the boiling point and contains the coolant. A sudden apparent rise in engine operating temperature can have many causes, ranging from a faulty sender, gauge, or thermostat, to a buildup of brake pressure due to a master cylinder fault which gradually applies the brakes as you drive. Carefully check potential causes before you start to change things, or it is likely you will mask the true cause.
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| TomO | -- 10-22-2009 @ 10:29 AM |
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Over heating is usually due to poor circulation of the coolant or insufficient coolant. Water transfers heat better than antifreeze-water mixture. Other causes are brakes binding or exhaust plugged. If the overheating only occurs at slow speeds, the fan is the problem. At speeds above 20mph the fan is unnecessary to cool the engine. Because the problem started suddenly, I would first suspect the thermostats then in order a bad water pump, leaky head gasket or plugged exhaust. If you can see signs of coolant circulating in the radiator, remove your thermostats and drive the car. If the temperature drops significantly, the thermostats are the problem. If the temperature drop is slight, then your radiator need to be flow checked and checked to make sure that the fins are attached and allowing air to cool the coolant. Tom
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| Grant | -- 10-22-2009 @ 11:50 AM |
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Hi Andy, Our '52 Ranch Wagon's 239 V8 started running hot after it was rebuilt. The problem turned out to have nothing to do with the cooling system. The metal vacuum line that runs from the diaphragm on the distributor to the carburetor was leaking. If you undo the nuts at each end which hold the line on, you will see that the ends of the line are flared ....... something like a brake line. Over the years the flared ends had worn enough to be sloppy. As soon as the flares were re-shaped to fit tightly and the line was re-installed, the overheating problem stopped. Before re-flaring the ends of this vacuum line, our TEMP guage was reading between the M and the P.....the needle had deflected 75% or 80% of the way over. Now that the line has been repaired and the vacuum leak has stopped, the needle isn't going any further than half-way between the T and the E. Perhaps this is your problem as well. One caveat ...... be very careful when doing up the threaded fittings: if you are not careful, you might strip the threads (especially at the carburetor). Hopefully your overheating issue will be as easy to correct as ours was. Best regards, Grant
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| 37RAGTOPMAN | -- 10-22-2009 @ 4:55 PM |
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does it overheat when idling ? or driving down the road, usually a back fire is from a leaking exhaust gasket, or maybe a leaking intake gasket ? if it overheats while driving, check the timing, it might be retarded, or not advancing when accelerating this will cause it to run hot in a hurry. is there any dragging like a sticking brake ? maybe the handbrake not releasing fully ? do a few check and lets hear how you made out, hope this helps 37RAGTOPMAN
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| ford38v8 | -- 10-22-2009 @ 7:57 PM |
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Scott, I'll side with the others here. We'll all gang up on you and put a flat motor in that brand x of yours. Your point that antifreeze boils at a higher temp than water is not at issue. We're talking about cooling system efficiency here: Plain old water transfers heat better than any other liquid. Alan
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| Steves46 | -- 10-22-2009 @ 10:27 PM |
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Hi Andy. Although I only have a few years of experience with owning a flathead, I would like to offer a couple of things you may want to check. With regards to the back fire, running too lean can lead to overheating. Did the overheating occur after you changed anything on the car? More times than not, problem(s) can be traced back to the last thing you did. Are the wires connected good and tight on your ignition? Good luck and hope you find the cause and by-the-way, if you do, please share it with us.
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| Pauls39 | -- 10-24-2009 @ 6:56 AM |
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Check your spark advance. The vacuum advance may have failed, the vacumm line may be cracked or plugged. Timeing that is retarded or too far advanced will cause your car to overheat. Set it per specs and be sure the vacumm advance works properly.
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| Andy0812 | -- 05-21-2010 @ 7:28 AM |
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Hi Guys, Thanks for all the info. Unfortunately, I put the truck away for the winter without solving my overheating problem. The truck is out of storage and I'm back on the problem.I am starting by having the timing checked. I'll move on to the others suggestions as I go along. As a novice my "gut" tells me this is tied into the backfiring issue. This is frustrating to say the least.
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| Stenny | -- 05-21-2010 @ 8:58 AM |
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The advice so far is spot on. If you determine that your timing is correct, pumps are working and thermostats are open, you may have a bad head gasket or worse, a cracked block. With the engine idling and warm (but not overheating), take a look into the radiator. You should see the coolant moving and this indicates that at least one of the pumps is doing its job.If you see bubbles, the exhaust is finding its way into the coolant and you will need to address this. Pull the heads and read the gasket if possible to determine if there is a breach somewhere. Clean up the block deck to try and locate a crack (visually or better, with a magnaflux kit). If the block checks out good, make sure the heads are true, replace the gaskets and torque to spec. Run the engine up to normal temp and re-torque the heads after cool down. If this does not cure your problem, you may need to pull the engine and tear into it
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