Consequences of not replacing thermostat?

iaind

iaind

iaind

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A few months ago a friend of mine bought his gold digger/sponge of a girlfriend a car - a 308 1.8 Meridian (against my advice to get a Focus or Golf :rolleyes:)

The first time I was a passenger in it, I noticed the thermostat was stuck open - it warmed up very quickly and cooled down when on the motorway. I told her that it needed replacing but the warranty would cover it. It had a 3 month warranty and she never bothered getting it fixed, apparently she likes it because the heater works quickly. She also doesnt believe me that its not meant to be like that because it sits on the 1/4 mark on the motorway and the 3/4 mark around town...

I know it's going to have an effect on mpg, which I dont really care about if she's paying for fuel. My concern is if there is a risk of any long term damage from not having it replaced as no doubt my friend will need to stump up to have it fixed. So is there anything more serious that can happen by not replacing it?
 
well itll be running hot around town. water flanges can warp, could kill the head gasket (it is french after all). its just not ideal for the engine

im not sure how the management on that engine works, but on the motorway it could end up drinking more if the ecu thinks the engine is cold, as itll chuck more fuel in

a stat costs a few quid...
 
If the thermostat was stuck open then surely it would heat up very slowly? It would cool down on the motorway as you suggest, but I see no reason why a stuck open thermostat would cause the car to run hot in town.

Similarly if you are mistaken and the thermostat was fixed shut, it would heat up quick, (as all cars should) and would then over heat.

It sounds to me like there's another issue hear. Perhaps a faulty sensor.
 
It starts to get warm very quickly but takes ages to get to a proper temperature if at all.

I dont know if it is overheating around town, the way he described it is that it was sitting on one of 2 marks on the guage - I assumed he meant the 1/4 and 3/4 but it could well be the 1/4 and 1/2 marks
 
iaind said:
It starts to get warm very quickly but takes ages to get to a proper temperature if at all.

I dont know if it is overheating around town, the way he described it is that it was sitting on one of 2 marks on the guage - I assumed he meant the 1/4 and 3/4 but it could well be the 1/4 and 1/2 marks
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Ah right, yes that makes sense.
A cold engine will run rich as has already been said, this could no doubt damage the cat and affect performance and mpg. Also the oil won't be working as well as it can below the correct temperatures.
Anyway it's something that needs sorting and whether in the long term or the short someone's going to be crying in the end.
 
Depending on how it is that might be normal.

My 306 which is admitedly a gti-6 warms up very quickly due to the exhaust manifold being towards the cabin, so you get warm air almost instantly.

The gauge will go up and down a lot, right up to the top of the gauge before the fans kick in at high speed, then it falls quickly down to 90C.

On the motorway it will sit at just under 80C.
 
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Berger said:
Depending on how it is that might be normal.

My 306 which is admitedly a gti-6 warms up very quickly due to the exhaust manifold being towards the cabin, so you get warm air almost instantly.

The gauge will go up and down a lot, right up to the top of the gauge before the fans kick in at high speed, then it falls quickly down to 90C.

On the motorway it will sit at just under 80C.
Click to expand...

Just because it does that doesn't mean it's normal behaviour... Unless of course you've spoken with others who have cars which do the same?

If that's the case then; ..... French cars...:rolleyes:
 
( |-| |2 ][ $;14080686 said:
Just because it does that doesn't mean it's normal behaviour... Unless of course you've spoken with others who have cars which do the same?

If that's the case then; ..... French cars...:rolleyes:
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Its completely normal, the gauge works properly, all of them do it.

I have a new alloy radiator, new thermostat and new coolant temperature sensor as well before you question that.

Most cars have a dead zone of 15-20C that the needle will never move out of unless something is wrong (ie you have no coolant) to stop people from panicing.

The difference being that the GTI-6 one tells the truth all of the time, so you will know exactly what temperature the engine is at, weather this is the case for the lower spec models or not I dont know, but im suggesting it as a reason for the above "problem" the OP is asking about.
 
( |-| |2 ][ $;14080686 said:
Just because it does that doesn't mean it's normal behaviour... Unless of course you've spoken with others who have cars which do the same?

If that's the case then; ..... French cars...:rolleyes:
Click to expand...

Its completely normal, the gauge works properly, all of them do it.

I have a new alloy radiator, new thermostat and new coolant temperature sensor as well before you question that.

Most cars have a dead zone of 15-20C that the needle will never move out of unless something is wrong (ie you have no coolant) to stop people from panicing.

The difference being that the GTI-6 one tells the truth all of the time, so you will know exactly what temperature the coolant is at, weather this is the case for the lower spec models or not I dont know, but im suggesting it as a reason for the above "problem" the OP is asking about.
 
Berger said:
Most cars have a dead zone of 15-20C that the needle will never move out of unless something is wrong (ie you have no coolant) to stop people from panicing.
Click to expand...

I can safely say that my 1992 clio doesnt have a gauge like that. Mine gets up to temp in a few minutes and the needle will then sit bang on the half way mark all the time, not rising and falling.

the only time it rises is if its a hot day and the car is stationary for a while. even then it will only rise a few notches before the fan brings it back down to normal temp again
 
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