I'm getting ready to flush the radiator on my 2000 XJ. Looks clean, but its been 2 years...and with the famous 0331 head, I figure I ought to be cautious...

Anyways, I was thinking back to years and years ago, when my dad used to run his '66 Dodge Coronet radiator with water in the summer and alcohol in the winter. He changed the fluid twice a year...Water and alcohol were pretty cheap...and water is a better thermal conductor than glycol.

Anyone know if that's a good idea or a dumb idea on my XJ?? Can I do that with the copper radiator that I have??

 

Straight water will corrode more than a proper mixture of antifreeze and water.

 

Seems like alcohol would kill water pump seals in no time. Use a name brand antifreeze/coolant.

 

Those were the bad old days, back when radiators lasted 2-3 years before rotting or clogging with sediment and the alcohol had to be replaced every so often because it would evaporate. Forget to do it and you'd freeze up. Antifreeze is a compromise solution, but it's a pretty good one.
Any particular reason you're considering plain water?

 

^^That's why we run 50/50....& dang Radi...that babbit is sure an improvement over pork rind eh?

 

Oh heck. Pork rind was an improvement over strips of oiled leather.

 

& darn, looks like there are plenty of wales left. Or were you runnen paraffin?

 

This. A 50-50 mix of coolant and distilled water is the best diet for your cooling system.

Conventional green antifreeze formulation (which is what I use and recommend for the XJ) contains a number of inorganic corrosion inhibitors that provide immediate corrosion protection because they maintain the pH of the solution (buffer it), but are consumed or transformed chemically as they perform their functions. As the coolant is heated and cooled, and exposed to air, the components of the conventional antifreeze additive package are depleted over time. This causes the pH to drop, and along with the coolant getting "dirty" with contaminants from the cooling system, is why the coolant should be changed on a regular interval; I generally do this every 30k or so.