Hi all

I am having a few strange things happening with the engine temp on my 2006 petrol vrs. Basically, its taking longer to be warm up than it used to and also dropping back from 90 to about 75/80 under light engine loads.

I am thinking thermostat but would appreciate any advice as its an expensive 2 hour job to change apparently.

Thanks

Matt

I bought one of those obd2 Bluetooth adaptors from eBay for £10 and hooked it up to Torque on my phone. Now I can see the actual temp and its worse than I thought.

After driving around for an hour this evening, the max I saw was 78 and it kept dropping down to 72. I could understand this on a diesel in cold weather but not a petrol.

I think this confirms my suspicion that the thermostat is stuck open. Dealers want over£300 to change it though.

Has anyone got any other suggestions or should I just go and get it changed?

Matt

Is your coolant/antifreeze mix ok, not too strong?

I would say its your thermostat mate.

Thermostat, mine did the same last year and slowly got worse during summer.

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Water pump?

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Thanks for all of your replies. The water pump was changed along with coolant about 12 months ago so I would hope its not either of those.

I guess I will take it to the dealer and see what they say although thermostat sounds most probable.

If it was water pump failure the temp would go up not down. As said thermostat is likely stuck open

If it was water pump failure the temp would go up not down. As said thermostat is likely stuck open

If the waterpump fails the usual symptom is a slow change downwards, sudden change upwards. Water stop flowing over the sensor, so it drops (as its not receiving a flow of hot water) and then rises (as the engine overheats and catches up with the sensor)

Yes but the op in this case hasnt stated there is any up surge in running temp, only that the engine has a low running temp and is unable to maintain even this lower temp.

In my experience if a water pump fails the temp will do nout but go up, this due to the sensor normally being in the thermostat housing, the pump pushes cold water in, so when it fails the hot water stays in the engine and upper radiator gets hotter and hotter.

If the thermostat is stuck open u get a constant flow of cold water from the radiator into the block, and as the thermostat cant close it cannot stop the flow causing low running temps.

Granted i havnt seen too many pump failures but in ten years as a mechanic i can honestly never recal a water temp going down when this happens.

Edited 20 February, 201313 yr by Craigt191