1.80 20V Temp gauge issues but not related to temp sender unit.

[Degudodger]

I have a long running issue with the temp gauge on my 1999 1.8 20v which needs resolving some time soon. Basically, at speeds of 70mph+ the temp gauge hovers between 65-70dgs but at lower speeds, for instance if I am driving round town, reports a temperature of between 80-90dgs. If I leave the car to idle it will reach 90dgs and go no further.

My thoughts are

Faulty Thermostat?
The heating works and both pipes to the radiator feel hot to the touch after 5 minutes of driving

Temp sender?
This has been replaced about four times over 3 years and I have made sure that each are from different batches.

Faulty instrument cluster
It's possible but I have no way of testing the cluster.

I have noticed a drop in fuel economy over the past 12 months which I initially put down to my style of driving, however if I drive the car conservatively I only average 31mpg. My drive in to work is no more than 7 miles, 3 of which are in 40mph limit and the rest in open limit where, depending on tractors and weather conditions I sit at 55-60mph.

What are your thoughts gents.

 

[Haggistech]

Mines does this i also have a 1.8 20v

i put it down to when sitting at higher speeds was alot more and cooler air hitting it so cooled it down

but am dumb when it comes to cars lol

my fuel ecomnomy is also pretty crap

sometimes as low as 27mpg

i also put it down to my driving

or needing a service

 

[Degudodger]

Glad it's not just me then!

I know my aircon works ok and the fan works ok - i.e comes on when it should.

 

[car_guy143]

My v5 doesn't fluctuate in temperature at all! I know it's not the same engine, but it is the same car so should expect similar behavior in temperatures. Once warm, it simply sits at 90 when moving at town speeds (30) and 90 when driving on the motorway and 90 at everything else in between.

 

[Haggistech]

mine did that until i had to get crank sensor replaced