My guess is you might have a resistance issue with the sender and
gauge.  Maybe an electronics guru like DB could cook up a resistor
value to get you in the ball park.They do need to be matched.  If you
still have the metal T stat housing, I would stick the sending unit
for the new gauge in that hole and rig up some sort of adapter.  If
the new sending unit doesn't have a real long probe on it, it might
no be getting to the warmest part of the coolant flowing by
either.  I installed my water temp sender by having a bung welded on
the big black pipe that comes out of the water pump, but that one
reads low too, likely from all the radiational cooling going on with
the air flow back there.  I'd try to get the sender as close to the
water jacket as possible.  You didn't mention what brand of gauge he
installed or part numbers for sender and gauge.  That might be
helpful.  Mr. Beirel has a better answer than mine, so listen to him....

At least you're getting a needle with "parameters" which is more than
you had before.  Gene Berg once wrote that any temperature measuring
device that doesn't cost at least $900(this was in 1970's dollars)
won't tell you the correct temperature.  Car owners are usually okay
with and can usually afford "close".

DAVID????????

DM&FS

At 09:53 AM 4/20/2011, Anthony Egeln wrote:
>Volks,
>Since he can't cure my ailing stock temperature gauge, my tech has
>installed an after-market gauge.
>If you have done this already, or if you would do this, where would
>you install the sender?
>He currently has it on a line near the thermostat, but the
>temperature has only reached as high as 140, and normally just gets
>to about 100.  So he will look for another spot.
>I will add that his thermal gun reads right at 195 at the thermostat
>when warmed up, so we know the engine is getting to the correct
>operating temperature, despite what the gauge reads.
>All ideas are appreciated. Thanks, Anthony'89 Syncro GL (Hidalgo)