Engine not getting up to temperature

[Brad.]

It gets to near the middle (90), then if I turn the heater etc on it goes down to 70. It's been Drinking fuel too.
Not sure, but I'm taking a stab at the engine temperature sensor? Still pulls fine, no noises etc...

Engine is a 1.4 8v

[alexperkins]

sounds like a good guess there mate. Get it changed

[Brad.]

Before i change the temperature, could it be the Thermostat?

Any idea where it is so i can check it?

[Bepe]

get the car running for 10mins or so, then feel the top and bottom pipes going to the radiator, if one is cold then its a stuck thermostat, if there both warm then its fine, id have my money on temp sensor though, especially if its drinking fuel

[alexperkins]

The thermostat opens at 84C - watch the dash temp and check it after its gone past that mark.

[Brad.]

Ok, will check the Thermostat tomorrow.
If it's not that, i'll replace the temp sensor. Hopefully it'll sort it.

[alexperkins]

The fact it drops so rapidly suggests something is wrong with the thermostat, but we will see

[Brad.]

Had it running, with the heater etc off so it got up to temperature.
Got out and felt both the radiator pipes, turns out the bottom on is cold, so that means I have a stuck thermostat i take it?

Any idea how to get it out to check, or even where it is, getting it out won't be a problem.

[alexperkins]

Its where the bottom rad pipe connects to in the thermostat housing - you can check it by removing it and putting it in a basin of boiling water and seeing if it opens or not. They arent that expensive to replace, so its worthwhile just getting a new one tbf!

[Brad.]

Taking it out and then putting it back though, don't i need to reseal the gasket with gasket sealant?

[alexperkins]

It should be fine mate

[Mart!n-GTI-DK]

Taking it out and then putting it back though, don't i need to reseal the gasket with gasket sealant?

No. It has an O-ring to seal it.

[Brad.]

Right, changed the engine temp sensor this morning. All went Dandy.

Was leaving it to Idle after I'd finished etc to see if it was going to make a difference. The engine will reach normal temp (middle of the dial) when the fans are OFF. If I turn them on, even to 1, the temp drops. If I turn it to 4, and the heat to max, the temperature gauge will visually drop.
I'm stumped, I think the thermostat is opening. Haven't had it out to check properly. If its worse case scenario, I'll get it out and put it in hot water, but draining the coolant is something I really don't want to have to do.
Any help appreciated.

[Brad.]

Ended up going to chat to a mechanic, its the thermostat.

[Tim_GTi]

It's definitely the thermostat mate, dead cheap fix, and doesn't take long.

You should receive a seal with the thermostat also.

All you do is remove the bottom pipe connected to the rad and drain the coolant.

disconnect all relavant pipes to the thermo housing, and unscrew housing.

Take the thermostat out, replace with new one, and seal (if supplied)

re-attach all screws and pipes to housing.

pour some water into your coolant tank and let it run out of the pipe at the bottom (the one you removed from the radiator), and repeat until water coming out is clear.

Refit pipe at bottom and fill coolant tank with 60% water, 40% G12 anti-freeze (the pink stuff)

when filled run car up to 90°C, squeezing all pipes.

run heaters on full heat and squeeze all pipes.

Top up coolant with water if necessary, then refit coolant tank lid.

Jobs a good one, takes half hour?

Then I've just realise how old this thread is, and you may well have sorted it by now!