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Tech Tip: Overheating

Originally written: 1981 for Brickline Vol.6 #2

by Duane West

Many of you have experienced overheating problems. Before I give you the cures, I'd like to explain the theory of overheating.

A bricklin with a 15 pound radiator cap will not boil the water in the radiator until the coolant reaches approximately 250 degrees temperature. With anti-freeze, the boiling point is 250 to 260 degrees. You can run your car at 240 or 250 degrees without hurting anything, as long as the water in the radiator doesn't boil. Once the water boils, it will immediately push water out the overflow, lower the coolant level in the radiator, and give you air bubbles circulating through the cooling system. Air bubbles do not cool an engine, so the engine temperature will immediately skyrocket. Your main concern should be to keep your engine below the boiling point of your coolant. If your radiator cap is no good, it will lower the boiling point of your coolant to 212 dgrees. A leak of any type anywhere in your cooling system will have the same effect. That is why you must have a good radiator cap on your car.

Many people get worried if their car gets up to 220 degrees. On a hot day, going up a hill with your air conditioner on, that is a normal temperature, and is nothing to worry about, as long as you aren't losing coolant. You can safely operate to 240. Above 240 you are nearing the boiling point of your coolant, so start being concerned. If you reach a point that your coolant boils, the radiator cap will immediately release the pressure on the radiator, and the coolant will immediately boil out the overflow. Now get worried!! stop the car and cool it off. If you continue to drive past this point, the engine temperature will skyrocket. The gauge will not show how hot it really gets, because the gauge will only read water temperature. Once the water boils, there is steam in the cooling system, and the gauge doesn't read steam pressure. The gauge can read 220 after overheating and boiling, but in actuality, it is closer to 300. Once the water boils, the gauge is useless. If you don't stop the car and cool it off at this point, you will cause engine damage, such as blown head gaskets, cracked heads and blocks, etc. Not good!!

Now, let’s get down to your car. If you are experiencing overheating problems on your bricklin, here is what to do:

  1. Check your fan belt. If it is loose, tighten or replace it.
  2. Change your thermostat. Install a 160 thermostat, a new thermostat gasket, and add at least 2 gallons of a good grade of anti-freeze/ coolant.
  3. Check the engine timing. Advanced or retarded timing will add to engine heat.
  4. Install a new radiator cap. You should use the cap that has the lever on the top because it makes it easier to check the water when the radiator has pressure in it.
  5. Check the fan clutch. There should be no side movement when moving the fan blade back and forth. If in doubt about the fan clutch, replace it.
  6. If overheating still persists, the radiator should be checked to be sure that it isn't partially blocked. If it is, have it rodded out. Don't just have it boiled out.
  7. If you haven't corrected the problem by now, i'd suggest installing a 7 blade stainless steel fan blade, and taking off the fan clutch that came on the car. This requires installing a 2' spacer to take up the room the fan clutch took.

The heavy duty stainless steel fan will pull a lot more air through the radiator than the stock fan, however, it will give you a little more noise because of the tremendous amount of air that it moves. The above should correct all heating problems unless you have engine problems such as a blown head gasket, cracked head, cracked block, etc. These tips apply to all cars and not just to your bricklin. If ever you have to replace your radiator, always buy a heavy duty one and not just a standard replacement one. The difference in cost is worth it.

A word about anti-freeze. Cheap anti-freeze is watered down. Always use "prestone" or the equivalent. If you use cheap anti-freeze, be sure to run 100% anti-freeze without any water added, because they already have some water added when you buy it. With "prestone" you can run 1/2 antifreeze and 1/2 water, or 100% anti freeze if you prefer. Fifty percent "prestone" and fifty percent water is a good mixture to run.

ENGINE HEAT - Originally noted in Bricklin Vol.1 #6

A helpful hint to aid both engine cooling and help eliminate some body curling resulting from inadequate engine compartment cooling is to remove the rubber strip that runs along the heater plenum in all 1974 and early 1975 cars. It is not necessary to remove the partial rubber in later equipped SV-ls.