Overheating, water pump, etc. Problem Found!!!!!!

[Jake Spoon]

Hi,

I'm choosing this way to respond to those that offered suggestions rather
than reply to each one.

I did this morning what I should have done about $250 and 2 weeks ago.  I
went to Radiator Specialties, the radiator shop that rodded out the used
radiator I installed, and got their wrench to diagnose the overheating
problem.  Result:  Cooling is normal;  problem is in the gauge.

I suspected the gauge at first but thought I eliminated it as a problem
early on.  I rigged the instrument cluster with some jumpers so I could
measure the supply voltage and reference voltage with the car running.  The
TCA700Y that I put in there recently was providing about 20% too much
voltage.  I found the lowest voltage TCA700Y that I had in my parts stash
and put it in.  I got 10V reference voltage, the spec is 9.5 - 10.5 V.  At
first blush that solved the problem.

Lesson learned.  Go to a wrench familiar with cooling systems that has a
laser temp gun;  they can do wonders toward deciding what's awry.

Thanks again for the help.

Cheers!

Jim Jordan