I can give you cheap advice, ... Ahh, ... I mean advice to keep the fix cheap.
Lack of antifreeze didn't cause the engine to overheat. Too much antifreeze can promote overheating because it doesn't hold many BTUs of heat so it has a hard time moving the heat to the radiator where it can be given up to the air. Water holds a lot of BTUs and does a real good job of moving heat to the radiator. That's why we include some in the coolant.
The bigger problem is acids form in the coolant due to combustion gases that naturally sneak into the cooling system. Antifreeze contains additives that include corrosion inhibitors to fight those acids, water pump lubricant, and seal conditioners. The lack of corrosion inhibitors in water could accelerate the formation of a leak in the cylinder head gasket, and that will lead to overheating. The combustion air that gets into the cooling system can pool under the thermostat and prevent it from opening and allowing the hot coolant to flow to the radiator. Thermostats open in response to being hit with hot liquid, not hot air.
For your needs, antifreeze has a higher boiling point than water, but that is irrelevant in the case of a leak. You'll see that your radiator cap will hold the system under about 15 pounds of pressure when it's hot. That raises the boiling point of water by 45 degrees to 257 degrees. That's why if a hose suddenly ruptures, pressure is lost and the water in the coolant turns to steam instantly.
The mud you're seeing could be the result of poor maintenance or oil leakage from the previous leaking head gasket that never got fully cleaned out. Other than an electrical problem and some staining from a previous issue, you haven't indicated whether the heater is working or if there's a problem. To tell if the heater core is plugged, feel the hoses after the engine is warmed up. The upper radiator hose should be too hot to hold onto for very long. The heater hoses should be just as hot.
You don't need any special tools to flush the system. Remove one heater hose from the engine. You can remove it from the heater core too, but without knowing how each one is designed, I don't like to twist the hoses on the heater core nipples because it's possible to put enough force on some to break the soldered connections and cause a leak. I'm not a fan of opening radiator petcocks either because it's pretty common on some to end up with a drip about once every five seconds that can only be fixed by replacing the radiator. Disconnect the lower radiator hose from one end instead. Also disconnect the reservoir hose from the radiator end and let it hang down.
Remove the radiator cap, then run water from a garden hose through the openings for a few minutes. Spray water into the reservoir, then let it fill up and run over to float the debris out. Next, hold your hand over the opening while filling it so some pressure builds up. That will force some water out through the rubber hose, and that will siphon the reservoir empty. Leave it empty for now when you refill the system.
Drain as much water as possible through the lower radiator hose, but understand you'll never get it all out. There's going to be about a half gallon stuck in places where it won't drain from. That becomes important to know when you're adding antifreeze later.
Reconnect all the hoses, then add a gallon of the correct antifreeze for your car. There's a lot of different formulations now so be sure to ask what's right for your car. A typical engine the size of yours takes about four gallons of coolant. We never go by the charts that show the capacities because we don't know how much water is already in there when we start filling. Next, add up to a gallon of water. You likely won't get it all in at first. Once the radiator is full, you'll likely need to burp the air pocket out from under the thermostat. Many engines have a bleeder screw on the thermostat housing at the end of the upper radiator hose. If there isn't one, you can remove a threaded plug or a sensor in that area, but that's best done with the ignition switch turned off. If it's on, an unplugged sensor will set a diagnostic fault code and could turn on the Check Engine light.
Start the engine and let it warm up. Keep an eye on the temperature gauge on the dash or for any hard gurgling near the thermostat. Those indicate the need to bleed the system some more. If the upper radiator hose gets hot, coolant is circulating and there's no more need to bleed the system.
It only takes a few minutes for the antifreeze and water to mix thoroughly, then you can test its freeze point. If you don't have an inexpensive tester, many mechanics will do that for you on their lunch break, or, if you bought the antifreeze from an auto parts store, they will be happy to do that for you too if they have tools to borrow or rent. Most of them do borrow tools now.
Once you know the freeze point, you'll know if you need to add water or antifreeze to adjust it, and up to now, the reservoir has been empty. That gives you a place to add what you need. It is going to take a few warm-up / cool-down cycles to draw in whatever is in the reservoir, so you'll want to wait a week or two to check the freeze point again. The goal is to reach minus 35 degrees. That is achieved with a 50/50 mix of water and antifreeze. Too much water will obviously raise the freeze point but so will too much antifreeze. The two have to be combined to achieve a lower freeze point than either one by itself. Too much antifreeze will give the illusion of a lower freeze point but it can promote overheating for the reason I mentioned earlier. Freeze point testers compare the weight of the coolant to the weight of straight water, so the coldest reading will come from straight antifreeze with no water, but most antifreeze actually freezes at around minus 10 degrees. It's the chemical reaction from mixing the two that the lowest freeze point is achieved, which is close to minus 50 degrees. The inexpensive testers are pretty accurate down to that point. For more accuracy including for much lower freeze points you need a "refractometer", but those are expensive and not convenient to use. Freeze point is not so critical in Florida. If you ever get down to minus 20 or 30, you might as well move up here to Wisconsin! For your climate, a freeze point of 0 to minus 10 degrees will still include enough antifreeze to provide sufficient additives, but those additives wear out in about two years so you'll still want to replace the coolant that often.
Friday, October 24th, 2014 AT 12:43 AM