How hot can it get?



Unfortunately, it got hot enough this summer to keep me too busy to write a column last month. What I mean is, I was kept busy with heating problems on several cars I hadn’t previously cured. Although I have written about heating problems before, there have been several requests to cover these problems again—possibly in more detail.


            Therefore, I will divide the problems and cures into two categories, with one this month and one next month.


            As most of you know, I am primarily into 1948 and earlier flathead V-8’s, however, most of the basic principles will apply to some late models.


            There are only two basic causes for these old cars to overheat. The first is for the cooling system to fail to remove the heat generated by the powerplant. The second is for the engine to generate more heat than the cooling system can take out. Does this sound like the same to you? Well, believe me, there is a difference.


            Unfortunately, sometimes you have some of both. Hot weather is not really the cause of overheating, but an aggravating circumstance that compounds the other problems. This month we will cover the cooling system’s failure to remove the heat. We will explore the causes for overgeneration of heat next month.


            Let’s look at the cooling system components which are five basic areas—the radiator, the fan, the water pump, the water jacket and the exhaust.


            Everybody understands the radiator…if it gets plugged, it can’t do its job. This can be easily cured by a good radiator shop with cleaning and rodding and the core needs to be replaced. This is somewhat expensive, but if you have to do this, spend just a few more dollars and get a high-efficiency core. Cosmetically, you can’t tell the difference, but it will give you 20 percent to 30 percent more cooling. If you “overpaint” the radiator for good looks, it will partially insulate the core, causing it to keep in heat instead of dissipating it.


            The fan serves two purposes. First, it pulls the air through the radiator core, cooling the liquid. Secondly, it blows air over the engine, taking away the hottest of air. In reality, if you never drive over 45 mph into the wind, you could probably do without a fan. However, if your fan belt is slipping, your car will heat very quickly in city driving, idling, or in low gear.


            Many people put on a six-bladed fan that you can get across the counter at NAPA. This doesn’t help a lot at highway speeds, but helps immensely in the city with stoplights.


            Assuming your radiator and fan are doing their jobs, the next step is the water pump, whose job is to circulate the coolant through the engine and radiator. Again, if the belt is slipping, it can’t do its job. This is a good time to remind you that fan belt tension is very important. If it is too tight you can ruin a water pump, fan bearing, or generator bearing and bushings—do not overtighten! It should be just tight enough to keep from slipping.


            The water jacket is that area in the engine block with chambers that contain coolant that absorbs heat by direct contact with the cylinders. The water flows through the block in and out of many nooks and crannies, picks up the heat that goes to the radiator, where it is dissipated and blown away. If the coolant can’t flow freely through the water jacket, the best radiator in the world won’t cool your car.


            If you have the engine out of the car for overhaul, have the block and heads boiled and dipped in rust solvent for a few days before you have it rebuilt. If you don’t have the engine out of the car, you can do a fairly good job over a weekend with some simple labor and few simple tools.


            First of all, drain the cooling system completely, including the block. Then remove all radiator hoses and the water pump. The hoses are removed to keep from filling the radiator with the debris and the water pump is removed to let out the crud that you flush loose.


            Pick up a cleaning tool that attaches to your garden hose or preferably to compressed air. Make a piece of 1/4-inch copper tubing to attach to the business end and drill some holes around the end so the water or air comes out the end in all directions.


            Now you are ready to do the cleaning. Starting at the driver’s side rear, remove one head bolt and insert the end of the tool into its bolt hole, turn on the water or air, and work the tool up and down and around until the water running out of the water pump cavity comes out clean. This may take awhile on the first hole.


            When you finish this hole, replace the head bolt and torque it down at that time, then go to the next bolt, remove it and repeat the process. Follow this process all the way forward on the driver’s side in each bolt hole.


            It is important to do only one bolt at a time and re-torque it before going on to the next one; otherwise, you can damage the head gasket and/or get water and crud into the valve chambers and manifolds.


            After you do the driver’s side head, then do the same on the passenger side, starting at the rear and working forward. You won’t need to do the front four or five bolts on the passenger side because you can clean this area through the water pump cavity.


            When you get to this point, it is a good idea to go back and redo one of the bolts on the driver’s side. This will clear out any sediment that has settled. You will be surprised how much guck you get out. This process will give you a much better flow through the block and that “guck” greatly slows the heat transfer from the metal to the coolant.


            You are now ready to re-connect the radiator hoses, but I strongly urge you to install filters in the upper radiator hoses to keep the loosened but unflushed rust chips from getting into your good radiator. I have found that the Gano filters advertised in the trade publications work real well and are easily cleaned...a very good investment.


            Earlier I mentioned the exhaust as part of the cooling system. Actually, the exhaust pipe carries away ten times more heat than the coolant.


            We will talk more about that next month, but for now, while the water pump is out, it’s a good time to insulate the exhaust pipe from the porcelain manifold to a point well below the water pump.


            Originally, asbestos was used for this but is no longer legally available. There are substitutes available that cosmetically look original but are nontoxic. This insulation is very important, especially on these old flatheads.


            The exhaust pipe between the manifold and muffler will run at 500 and 1000 degrees and sometimes more. This pipe goes right next to the water pump and can reheat your radiator-cooled liquid before it gets a chance to cool your engine. The difference between an insulated or non-insulated exhaust pipe can mean 30 to 40 degrees difference in en-gine running temperature.


            You should now be ready to fill the radiator. Use a mixture of 50 percent quality antifreeze and 50 percent distilled water. It is foolish not to use distilled water at a cost of less than three dollars because tap water in most areas contains chlorine, fluorides and other chemicals that cause a lot of that crud in the first place.


            We didn’t talk about leaks because it is very obvious what happens when all your coolant leaks out. Next month we will talk about reasons the engine can generate more heat than the radiator can dissipate.


            As the old saying goes, “Some Like It Hot,” but that should only apply to love affairs, music and food—not your engine.


            See ya next month.