GPZList Digest, Vol 137, Issue 2

[Jeff Walker]

   RE: Running hot and electric fan kicking on quickly and more often and
   running longer. I suspect that your radiator is starting to foul the
   surfaces inside. Corrosion products build up and contaminants and
   dissolved solids start to plate out, all of which insulates more and
   more and impedes heat transfer out. You could try doing a citric acid
   flush to see if it improves, and that is part of my normal annual
   maintenance routine now. When it comes to radiator fouling, it only
   ever gets worse over time. Good quality coolants designed for aluminum
   with a higher initial concentration of corrosion inhibitors added helps
   too. But it's generally a time dependent condition, not milage
   dependent.
   The next thing to check is the coolant pump. Just as the radiator gets
   fouled, those dissolved corrosion products and contaminants errode the
   pump impellor over time...less discharge pressure and lower flowrate
   results. Lower mass flow rate of coolant = lower heat transfer rate out
   of the radiator.
   I'm sitting at nearly 140,000 miles on my 1996 now. The largest
   maintenance headache I've had the last couple of years is bad gas
   gunking up the pilot jets, and the absolute pain of getting the carb
   bank in and out with slightly hardened and worn out carb boots. Other
   than that, it's just been tires, oil, coolant flushes, chain and
   sprockets, brakes, valve clearances, steering head bearings and wheel
   bearings. I did have to rebuild the rear brake master once when it
   started sticking and the fuel petcock...but that's it. Over 140K
   trouble free miles.
   Jeff in WA