Car Temperature Advice

[DiamondGeezer]

Uncle's got a 1989 1.4 polo

After the car warms up the needle goes to the halfway point and has always stayed there no matter if he was driving in town or motorways

More recently on motorway driving only the needle now falls back to a quater (running a lot cooler) and once back in town stop/starting etc it goes back to the halfway mark

Any reasons why it is now behaing differently

cheers

 

[thebigman]

thermostat prob sticking open. replace it.

thebigman

 

[dogtoffee]

As said more than likely the thermostat if not it could be a faulty temperature switch.

 

[thebigyin]

most likely problem is the thermostat or the thermostat housing mate but as long its not going by half way as over heating could mean more expensive problem

 

[DiamondGeezer]

Thanks for the quick replies guys... I'll pass this on to my uncle

just a couple of questions though (what I know about cars is not worth knowing)

As said more than likely the thermostat if not it could be a faulty temperature switch.

If it was faulty wouldn't it just be stuck quater off the way all the time?

thermostat prob sticking open. replace it.

thebigman

Again why would it show normal in traffic but change on the motorway

 

[DiamondGeezer]

most likely problem is the thermostat or the thermostat housing mate but as long its not going by half way as over heating could mean more expensive problem

dosen't go over half way so that a relief

cheers

 

[thebigyin]

dosen't go over half way so that a relief

cheers

also mate its a long shot but make sure the radiator fan is not stuck on when you start the car make sure the radiator fan is not comeing on straight away. it shoud only come on when the car heats up

 

[MikeS]

car sounds fine to me

most car now have a coolant temp sensor that controls fueling. timing, air

so that sensor gets the car up to operating temps and tries to keep it there for optimal running

it drops on motorway due to the amount of cold air hitting your rad

 

[thebigman]

Thermostat opens to allow water to circulate through radiator. At idle as there is no air being forced through radiator the car will reach normal temp, while driving air is passing over radiator cooling the water as it flows round the system. Normally the thermostat closes to maintain temp. Its a pretty simple thing to test the thermostat(kettle and a thermometer) and they are not usually expensive. Stuck open doesn't cause any real problems except heater blowing cold air while driving, stuck closed causes overheating and engine damage as a result.

thebigman

 

[thebigman]

car sounds fine to me

most car now have a coolant temp sensor that controls fueling. timing, air

so that sensor gets the car up to operating temps and tries to keep it there for optimal running

it drops on motorway due to the amount of cold air hitting your rad

The coolant temp sensor monitors engine temp, the engine control module uses that reading to control control fuel/air mix but it is the thermostat which controls the the actual engine temperature.

thebigman

 

[DiamondGeezer]

car sounds fine to me

most car now have a coolant temp sensor that controls fueling. timing, air

so that sensor gets the car up to operating temps and tries to keep it there for optimal running

it drops on motorway due to the amount of cold air hitting your rad

His had this car for 10 years and it always been on the halfway mark until recently

 

[IANB]

new thermostat will sort it out. Inexpensive and quick to fit.
Its worth getting done as the engine is more fuel efficient at the correct temp.