It's Summer time and many here won't want to drive their oldies because they run too hot or boil over .
The solution is dead easy and only takes a little bit of money and some time .
Find Citric Acid powder, often sold as "Sour Salt" in baking supply places, I buy it OnLine *very* cheaply as food quality Citric Acid powder .
Buy five pounds and you'll have some left over .
Get some clean jugs (rinsed out milk jugs are *perfect*) and a funnel that fits in the radiator's neck, (Dollar store) , mix one pound of the Citric Acid powder to three gallons of water , drain the cooling system (remember to turn the heater to hot) , fill it, run the engine a bit to flush out the remaining coolant and drain again then fill with the Citric Acid and water mix, allow to run until the thermostat is open and the mix is circulating, if it has a heater the heater will blow hot when the 'stat opens .
Now, GO DRIVE for at least 30 minutes ~ I like to drive it to work and home a few times, no matter how clogged the radiator and water jacket is, this mix will gently and slowly dissolve all the accumulated rust silt in the lower corners of the water jacket and those crusty things you see growing on the radiator tubes when you peer inside ~ that's called 'solder bloom' .
After a while the mix will turn red then black, don't worry and don't rush it, it cannot hurt anything, this can be used on that $500 Japanese car out back that needs a new radiator too .
After a long bit of running the engine drain it all out (mind you don't stain the clean concrete driveway) , refill with clean water and 1/2 box of baking soda , drive it at least 10 minutes, (DRIVE not idle !) to , drain it all again and run the hose in the radiator as the engine idles until the water running out the coolant drain is clear, then close the drain and mix about three gallons of good quality coolant @ 40% coolant and 60% water (I use & recommend GL5) and slowly fill the cooling system, run the engine until it's warmed up and the heater blows warm, take it for a drive and you're all done .
The main thing here is twofold : mind the 60/40 % mix and don't rush it nor think that allowing the engine to idle a long time will do the job because it won't ~ you need a high rate of coolant flow that only comes from driving the rig .
Be aware that older vehicles tend to seek their own coolant level and usually need 2" air space at minimum so if it's not overheating yet "uses coolant" you're probably overfilling it a little bit .
That's it ! .
As long as the coolant temperature remains below 230* F it's not overheating .
Save this as it will be useful sooner or later.
-Nate
