I posted a while back about my overheating '98 Sable -- the engine would
operate at a normal temperature on the highway for about 20 or 25 miles,
then the temperature would suddenly climb. It did this with a new water
pump, new radiator, new thermostat, several flushes, replacement of the
reservoir cap, pulling of the freeze plugs to check for sludge buildup,
It had passed the compression test on the head gaskets, but since the
problem obviously was nowhere else, they went ahead and pulled the heads.
One head was warped by 7/1000. The other was warped by 9/1000.
They sent them to a machine shop to be redressed.
$838 later, my overheating problem is fixed, I have better engine
performance (more power), it runs even better than it had before when it
was running normally, which I thought was great, and that nagging
clattering problem I'd had for 50,000 miles is also fixed. It had been
clattering a little even burning premium. It sounded absolutely horrible
when burning regular. Now I'm burning regular gasoline and there is
absolutely no clattering at all.
So I'm very pleased and with the amount of gas I burn (about 230 gallons a
month) I'll now be saving about $69 a month on gas. :-D