Water pump stealth failure?

[Jim Jordan]

Hi,

I still have indicated overheating on my 5KT.  I've replaced virtually
everything in the cooling system except the water pump.  It was replaced
about 20K miles ago along with the TB.  I suspect that the garage that was
supposed to replace it didn't or used a junk one.  The one that was in there
prior to that "work" was a lifetime warrantied Graf which doesn't have a
good rep in some quarters.

Does anyone know a way to check the water pump short of removing it and
inspecting it?  Obviously, if I remove it, I might as well do the TB in the
process, which I don't want to do now.  

I drove the car on the freeway today about 50 miles total, ambient temp was
90+ F, and the temp gauge sat just under the top mark when driving at
highway speeds.  I measured the coolant temp in the expansion tank just
before shutting down at ~180 deg F.  The fan came on during driving and shut
down shortly after I shut the engine down.

Thanks for your ideas. 

Cheers!

Jim Jordan