temp guage problem

**sri-case** · 13th July 2010, 21:51

Hi, ive just bought a 1.8 sri veccy on a 52 plate, the problem is the temp guage drops to zero whilst driving (especially whilst on motorways) but then goes back to normall when stopped or going round town. any ideas?

**barney490** · 13th July 2010, 22:07

possibly thermostat stuck in the open position. Time for a new one me thinks,

**sri-case** · 13th July 2010, 22:13

nice one anythings worth a try, dosent seem much of a problem just annoying not having something work properly. cheers

**leebutcher2.8** · 13th July 2010, 23:16

one thing to try:

be careful and fully read and understand before carrying out this !!

Take off rad cap and start engine, let it warm up and watch the fluid in the tank, once engine has run 4 -5 mins the fluid should start to flow ( seeing move within the tank ) temp reading below normal just. Once you see this you can be happy your thermostat is opening and re-place the rad cap.

if no movement in the water give it a few more mins but be ready to replace the cap if bubbles start to be visible in the tank, a good tip is to have a dish towel wrapped around your hand and a bowl of cold water at the ready.

dont want to get burnt by the boiling water in the system, if you get it all wrong and water boils from the tank ( Leave along ) Dont try to refit cap and turn off engine and let become cold and top up as needed.

be-careful but sure fire way of see if thermostat working.

**ROCKATANSKY** · 13th July 2010, 23:18

I would have thought it was the sender for the guage rather than the thermostat coz then the thermosat opens it'll still be hot enough for it to register on the guage. That what it was on mine.

**Exclusive BV** · 14th July 2010, 11:23

There was a similar thread a while back, a lot of 1.8's are doing this (mine included).

My previous astra did the same.

A vx mechanic once told me it was normal but I dont know how true this is

**Jezzy** · 14th July 2010, 11:36

I had it happen on a Rover years ago - when driving on the motorway the temp guage would drop to the lowest point (less that 70 IIRC) - the thermostat was stuck open and letting coolant through to the radiator even when it wasn't hot enough, and the airflow at high speed was cooling the water even further.

**CLOMP** · 14th July 2010, 17:04

Originally Posted by Exclusive BV

There was a similar thread a while back, a lot of 1.8's are doing this (mine included).

My previous astra did the same.

A vx mechanic once told me it was normal but I dont know how true this is

the vx mechanic who told you this is a ****, its not normal, mine stays between 87 and 92, the fault with the OPs car is the stat/ temp sender.

**Das** · 14th July 2010, 17:07

Yea my 1.8 does this too. Where is the stat/ temp sender located?

**barney490** · 14th July 2010, 17:17

not sure where it is on the 1.8 petrol, but i would guess right hand side of the engine, held on by two or three bolts. The stat is usually supplied with the housing and temp sender included, although you can buy the sender seperately. Change the assembly.