Hi all,

After help from other users under tuning i now have a technical question.

Can a faulty thermostat cause higher fuel consumption and loss of power?

Im guessing yes due to the fact the car is always trying to get up to temp hence using more fuel and when i boot it im adding more fuel which in turn is slightly flooding then engine so getting less power and slight bogging down.

does anyone agree or am i just talking B*ll*cks?

Thanks

on my current jtd 1.9 an past 1.9/2.4. it uses more fuel cold and is not best to boot it till it warms up, when warmed up it will burn fuel more efficient. i might be wrong but thats what i have always found?

which in turn as you say would affect the power, but i wouldnt of thought it would effect it alot. might depend on engine size Petrol/Diesel. could it be sticking?

Hi,

Should really have specified the engine lol.

its the 1.8. The problem is, it never gets up to temp (according to the gauge)

Yes a faulty thermostat can cause high fuel consumption. If the thermostat has failed in the open position then the engine will take longer to warm up and the ECU will add a little more fuel as it thinks it's still in a cold start mode.

How far up the gauge does the needle go?

id start it outside your house leave it for a bit with a few rev in between? are the distances you do short?

i dont have the 1.8 but im sure they all work the same! the 1.8 stilo gang would have the bet idea. id leave it on tickover for abit see if it does anything

Hi all,

Needle only reaches first line and stays there even if its a short 5min run or a 2hr run.

But if i leave it sitting on the drive for about an hour it will go up to the middle but as soon as you start driving it it will drop to the first line

yup, as above, it will cause issues, though some may argue otherwise


I had a similar issue on my jtd, needle never reached operating temp, which is half way on a jtd and probably the same on the 1.8. Its a simple fact that the engine has an operating temperature that it works best at, and if the engine cant get to that temp easily, then all sorts of very minor issues can occur such as fuel consumption increase, fast idle, poor response and so on (all quiet minor though).


I did my thermostat a short while back, arse of a job, but the result is a nice warm engine within minutes, stable half way needle no matter what the mileage and fuel consumption back to normal.

Yeah I agree it's a classic case of a duff thermostat. It's stuck open hence why it instantly cools down as you drive because the cool air rushes through the rad and cools it down.

I have the 2.4 and I believe the 1.8 is of a similar design just narrower and when I changed mine I didn't find it too bad a job. The bottom bolt was the only difficult one but after that it was a job in the town

I had a faulty thermostat on my 2.4 which was stuck open, but it I wouldn't say it caused higher fuel consumption. . . The most annoying part of it is the lack of heat inside - mine's a climate control so it diverts what it thinks is heat from the engine . . it was a cold winter!

Yours is definitely stuck open. With the engine running and static, the car gets up to temp and the fully open thermostat cools it to the optimum middle mark - if it's really hot the fan kicks in the help. Problem is when you drive the car the air rushing in the engine cools the it as well . . - normally the thermostat would close (it's a wax that solidifies) - but if your fully open the engine is getting doubly cooled - hence the cold.

I wouldn't worry about it in the short term - just don't gun it until you get a new one. they're cheap and easy to replace.