Replace thermostat to fix temp / mpg problems?

[lighters]

GOLF MK4 2000 1.8 gti W REG AGU.

Lambda sensor fine
Fuses are fine.
Blowers push warm air but not as hot as they used to. (seem to get hotter as temp guage rises)
Plenty of water in coolant.
Cambelt and waterpump just been replaced

Temp used to hover around 90c but now it barely moves. It never reaches 90c anymore and stays near the botton, it does climb up when revved and stuck in traffic but not 90c.

Based on the faq I need to replace the thermostat? ECP anygood?

I used to get 40mpg at best and average of around 36 but recently the best I can get is 32/33 on long motorway journeys as it was 30mpg before a recent service.
My car also fails to start sometimes as it will stall (read this can also be due to thermostat)

I have also seen people mention the temperature sensor and temp sender (Correct spelling), are these all the same things under different names or can someone give me a clear concise answer of each different part and what they do? Reading online just gives conflicting information.

P.S - Where is the best place to get thermostat? VW? or ECP?

[mcgee9t2]

thermostat is a mechanical part that opens and closes depending on temperature of coolant etc. common symptoms are that your car wownt hit 90 unless stationary, and will drop again once you start moving.

temp sender /temp sensor is an electrical part that measures the temperature. common symptoms are again car wownt hit 90, however temp sender is normally more eratic i.e one min you can be driving and it wownt hit 80 the next minuite it will be reading 120 etc.

both will reduce your mpg as the car will over fuel slightly.

temp senders have a tendancy to make your idle fluctuate on start up (however my t/stat did this).

i have heard in the past of peoples cars not turning over streight away, then once temp sender is replaced its fine so temp senders can have this symptom though not always.

i believe temp senders will bring up a fault code in some cases.

t/stat will not as it is not a electronic part.


IMO best place for sensors and thermostats is VW, then you know you are getting good build quality.

people however have used ecp and the likes for sensors and thermostats and got away with it, however others have not been so lucky and have been replacing them again a few days later.


locations are as follows.
thermostat - located at the front of the engine, left hand side (as your looking at the engine), around half way down, there is a pipe coming out of the engine, this is the thermostat housing, the thermostat is in there.

temp sender - located at the front of the engine, at the top, right hand side of the block as your looking at the engine

[Luke1981]

As above, I would get it from VW mate. My money is on your thermostat being faulty.

[mcgee9t2]

FYI. tstat from vw is around £27 inc VAT.

unsure on temp sender. think that may be around £15 ish, but dont hold me to that.

[northeast_gti-t]

Sounds like a thermostat will need replaced,best to really given the time of year etc,yes ecp and gsf etc etc are okay for a stat i would sooner pay the bit extra and get a o.e.m one from vw i had a non genuine one in mine and ended up changing it for a vw one in the end.

[Bellend]

Please avoid cheap thermostats from anywhere. ECP do a good OEM quality sensor though, never had any trouble and one car was on it's second year the other week (I do a full VAGCOM flick thru with a service) and spot on.

Most points good here, thermostats CAN cause fault codes though. Not in themselves but their symptoms sometimes ping up a code.

I'd change both for piece of mind anyway but if you can get it on VAGCOM you can check the temp sensor as they don't always stick a fault light on but live data will show you.

Your thermostat is definitely faulty though matey.

[boneybradley]

I sell BGA thermostat kits for £12.50 (p&p £3) and I have used them in all my vw's for years (with no issues)

I can do o.e at £27 (p&p £3)