19-04-2018, 08:15 AM
more thoughts whilst trying to sleep.
please bear with me on this.
what's the history of the lump? is the original or sourced elsewhere?
has it been flushed/descaled?
if it's not mechanical, could it be electrical? ie, engine/dash earths? my gauge pod is powered with a cigarette plug. if I jiggle the plug, the readings change.
do the sender and gauge match? ie a 0-50 psi gauge would need a 0-50 psi sender. the sender itself is just a variable resistor.
is the sender one or two wire? 1-wire feeds to earth, 2-wire feeds "through".
finally,
consider getting a meat thermometer (a skewer with a gauge attached) and some self-amalgamating tape, stab it carefully into the top hose when the car is up to temp, and read the coolant temp directly. the tape is to seal the hole afterwards, (you need to stretch it slightly to self stick).
Oh, and are you using waterless coolant? I gather it doesn't suit all cars.
please bear with me on this.
what's the history of the lump? is the original or sourced elsewhere?
has it been flushed/descaled?
if it's not mechanical, could it be electrical? ie, engine/dash earths? my gauge pod is powered with a cigarette plug. if I jiggle the plug, the readings change.
do the sender and gauge match? ie a 0-50 psi gauge would need a 0-50 psi sender. the sender itself is just a variable resistor.
is the sender one or two wire? 1-wire feeds to earth, 2-wire feeds "through".
finally,
consider getting a meat thermometer (a skewer with a gauge attached) and some self-amalgamating tape, stab it carefully into the top hose when the car is up to temp, and read the coolant temp directly. the tape is to seal the hole afterwards, (you need to stretch it slightly to self stick).
Oh, and are you using waterless coolant? I gather it doesn't suit all cars.
It goes, it stops (as reqd). 
Hate Housework!
Hate Housework!