I need to replace the anti-freeze in my '90 Cougar LS and have been reading the past threads and sticky regarding the same. The one thing that I have been unable to determine is if there is a way to purge the block of the coolant mixture. Sure, I can drain the radiator of one gallon of coolant, but according my owners manual, my car's coolant capacity is 11.6 quarts, which means that there still is close to two gallons of old,dirty coolant in the block.
A few members have posted that they just drain the radiator, add water to the rad, run the car for a while until everything mixes up and then repeat the process a few more times until the original coolant mixture becomes diluted down to a reasonable level. Then they fill the radiator with straight antifreeze.
Ok, yeah, I see how this works as far as flushing the cooling system of it's old mixture and ending up with a mostly water/minimal anti-freeze mixture. But, you still end up only draining the radiator of it's one gallon capacity and when you finally decide to add a jug of 100% antifreeze to your freshly rinsed out cooling system, you can only add one gallon. In other words, your new fresh mixture is roughly 1/3 antifreeze and 2/3 water. Not exactly what is recommended.
So, has anyone figured out how to purge their engine block of old coolant after draining the radiator?
What about compressed air through the vent plug?
Just a couple of other things. Yes, I did disconnect the lower radiator hose after I drained the radiator - hardly any more coolant drained out. And I even tried what the counter man at a local parts store suggested. He said that if I pulled the coil wire off and turned the engine over with the drain cock open that the engine would pump the coolant mixture out of the block.
What about the thermostat being closed I said and that the coolant was only being pumped through the engine when the car was cold. He said something about the water pump circulating coolant through the radiator until the car warms up and then when the thermostat opens up does it circulate the coolant throughout the entire system. Have I just learned something new?
Have I had the function of a water pump all backwards all these years? Wouldn't be the first time for sure. So I tried his tip anyway - nodda drop came out the radiator drain cock. No duh...
Also do our 3.8's have any of the cylinder drain plugs that are mentioned in the Cooling System Draining/Filling/Bleeding Procedure tech article?
Please if you can give me a few ideas on this, I would sure appreciate it.