Had a weird thing happen while checking out a customer's van today.  Ran the
van up to temperature and let it idle.  It went slowly up to around 3/4 of
the gauge before the fan came on.  I put in a new switch that now comes on
right after the needle passes the LED (better).  However the van did
something weird when I was trying to warm it up after replacing the switch.
The needle was at the middle (LED) and I wanted it to heat up faster so I
revved the motor up to around 2500 rpms and held it there.  As I watched the
needle it actually went down in temp 1/8 of the gauge and then started back
up again!  I had never seen this before (usually they hold steady and slowly
climb).  Any ideas on this one?  Just normal operation and I never noticed it
before (possible)?
The old fan switch might have been good but the part of it that sticks into
the rad was covered with goop (Bar's Leak?) and this could have had an
insulating effect on the sender.
I was wondering if the inside of the radiator is coated with goop if this
could be messing up its heat transfer properties?  Any ideas?

Thanks,
Ken Wilford
http://www.vanagain.com
John 3:16
Phone: (856)-765-1583
Shop:   (856)-327-0027
Fax:     (856)-327-2242