slow warm up times - thermostat or temp sensor problem?!

[audi-tone]

Hey guys, since getting colder my car's been taking longer to get to normal operating temp (90 degrees); eg. today drove for 20mins (about 18km's) and i only got to about 80ish degrees. didnt even get to 90 before having to turn it off. at one stage it went down in temp. Only two possiblities i have researched are the temp sensor or the thermostat.
which one is it more likely to be as i cant believe it should take this long to warm up. used to take about 6mins tops. (in hotter weather mind you, if this has any bearing on how fast it'll wamr up)

Thanks

[dylan8]

i found this was caused by the thermostat in my car. my thermostat is jamming and not 'closeing' im lead to believe. I wanted to get the old part to have a look at but forgot...
Could just replace both? temp sensor costs next to nothing, and from memory the thermostat wasnt a horrible pain to the hip pocket either.

[gareth_oau]

my thermostat went on my S3, which I suspect is the same on your Mk4.

it took forever to warm up, never hit 90 and would cool down on freeway runs.

The thermostat was about $18 plus an hour labour

[dubbed]

On a similar note - my car comfortably sits on 90 degrees, however, when I use the heater it never hits 90 (always remains about 80). Is this normal?

[gareth_oau]

the heater is an extra heat exhanger in addition to the radiator, so it makes sense that it would run cooler.

however, not sure if its supposed to. any views out there?

[audi-tone]

where are you getting the thermostat for $18 from?!?!?! called vw today and oem part is $72! bit rich i thought? can i use a standard replacement from a different auto shop??!?

[JustCruisn]

where are you getting the thermostat for $18 from?!?!?! called vw today

There's the problem right here.

The dealer is only good for getting the correct part number so you can start calling around.

GermanAutoParts.com

[Dyldo]

i'm not sure if what I have is a thermostat related problem - but it sure sounds like a temp sensor type problem to me. When i start my car, i used to see her idle for about 2 mins at about 1500rpm or so, and then settle right down to normal idle when she was a bit warm. Now, however, she doesn't idle high at all, she just starts up and goes right to normal idle speed.

trust me, its damn cold in the mornings at my place and I figured she'd need more of a warm up than normal, but there is none at all. Thoughts?

[Jmac]

Check the temp sensor activity with a scanner. Sounds like throttle body
Jmac

[audi-tone]

Hey fellas, had a look at repco today and found a generic thermostat (either 82 or 91degrees) and it was about $14.
Is it totally advisable not to use a generic product? any differences between genuine and generic?!

cheers