On Jun 17, 2011, at 4:30 PM, YES NOPE9 wrote:

circa 1990   same engine , replaced water pump 5 years ago.
gradually overheats on long drive.
no coolant is missing.
fan belt is quiet ... does not appear to be slipping.=20
turning on interior heater with fan brings temp down. =20
    flow diagram seems to indicate that heater bypasses thermostat. =20
radiator is brand new ( 6 months )

PROGRESS.....
I have installed a new thermostat.  The old one seemed to have lost the abi=
lity to warm the car up rapidly.  On Saturday 2011m06d18 I drove the Miata =
on a longish ( 30 minute ) uphill drive. The temperature briefly went above=
 normal position ( 50% ) during one climb ( to 60% ) and then returned to n=
ormal.  The Miata seems to warm up faster ( much like it did when it was ne=
w).  I had felt that maybe the thermostat was not closing properly which ha=
d caused the slower warmup to operating temperature. =20

2011m06d19
So I do not think the problem is corrected.  I will now look at the water p=
ump.  I will also flush the coolant system.


MISC.....
For those wondering about the engine being 5% shorter .......
See this video ............
http://www.youtube.com/watch?v=3DRap5NohGd7w
Also note I have used an alligator cable in place of the proper temperature=
 switch for the radiator fan.
( Yes the fan is spinning )   I am looking for a generic temperature switch=
..
99guspuppet







--=20
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