The temperature gauge on my MK 1V is giving wildly variable readings, which make driving a tense experience.
Some background facts;-
The car is not losing water.
The std top hose filler has been replaced by an inner wing mounted header tank linked to both top and bottom hoses.
I have put an electric fan 182 deg water temp sensor in the bottom of the top hose near the radiator joint.
I have put tell tale strips on top of the top hose near the thermostat housing, on the bottom of the top hose near its entry point to the radiator, and on the radiator next to the temp sender. The one by the thermostat housing shows the highest temp at 87 deg. 84 deg at the top hose near rad.
The water seems to be circulating properly with top and bottom hoses getting hot and warm respectively.
However, the gauge seems to have a life of its own, which is very disconcerting.
Sometimes it settles down for a while around 82 deg sometimes in the 90’s. Quite often it will quickly move from mid 80’s up to around 100, and back, sometimes settling back to a different temp than its start point.
The fan cuts in, I have to assume at around the correct temp, because of what the tell tales suggest.
Has anybody out there suffered similar issues, and if so what is the fix?
I am currently leaning towards replacing the gauge, but as it is inaccessible behind the centre console, is not something I look forward to attempting.
Please let me know your suggestions.