cdti 150 coolant temps, is this normal?

[IrishVectra]

The temp gauge on my cdti 150 is a bit of a strange one. Its my first diesel so not sure if its normal or not.
I can do a non-stop 5 hour motorway journey and the temp gauge will sit on 70degrees the entire way, ie not move from cold.
I have the heat set slap bang between hot and cold and the fan on setting 1 so the vents arent sucking much heat out of the coolant. Occasionally the temp needle might move up to 73ish degrees but thats only on a warm day. Now if i then hit city traffic, stop start the temp will suddenly rise to 90+degrees.

Is this normal on these engines? Just find it odd how the temp doesnt go up despite hours of use but will rocket in city traffic. It'll then go right down to nothing once the car is moving on the open road. Lol is this normal or have i just got a seriously effective radiator?

[Mission1979]

Mine did this from when I bought it until about five months ago when I changed the thermostat. Now it sits about 86 degrees after it gets to temperature after about ten minutes. Get one from dealer, cheaper than most most spares places.

[taffy bhoy]

just bought a new thermostat with housing and new sensor already fitted to it from vauxhall today for our 1.8 with identical problems, £44 all in with the discount i get from another site,

[keith150882]

Same here! I just put it down to when your do 65-70mph in 6th gear car is only doing 20-2500rpm so it's only just ticking over but if traveling on B roads with a bit of gas it sits at about 80

[IrishVectra]

righto i'll change the thermostat so, thanks for the replies guys. Been a while since i worked on a z19dth, its on the gearbox end of the head isnt it?

[AntSSSS]

Classic thermostat issue mate on the CDTI's - get a genuine VX only one.

A

[mike.]

I had this issue when I bought mine, fitted a thermostat and now sits around 80 degrees

[stevoxsi]

Me too! Get a thermostat in her!

[SlowCoach]

righto i'll change the thermostat so, thanks for the replies guys. Been a while since i worked on a z19dth, its on the gearbox end of the head isnt it?

Its next to battery. Stand on nearside and look, 4 hoses attached with plug.

[mrk]

would this effect mpg? i average 42 mpg and tp rarely goes above 75°