advise please

[passat tdi130]

g'day chap's i changed my thermostat about 12 to 18 months ish ago i bought a gates one from good old ebay today while on a very long journey to london and back i noticed the temp gauge up and down between 90deg and 80+/- a couple of degrees

the bottom hose to the stat is pretty cool after a 500mile round trip at a healthy ( ahem ) 80+mph i plugged car into vcds and coolant temp showed about 72deg left ticking over for 10 mins struggled to reach 80.6 degrees heater blower off put heater on hot blower on and temp dropped down to 70+ish

im assuming the stat is buggered already i thought these gates stats were supposed to be a quality one..?? any view's on that

also i changed the maf sensor on wednesday the maf wouldnt cause this would it..?

the average mpg seems miles better with the new maf around 48mpg at around a constant 80mph all motorway but as mentioned temp up and down..!

also i noticed the timing is between .6 and 1.1 is this ok as i have read in some places it should be 0.0 or as near as..?

any help really before i go buying a genuine stat tomoro / friday

cheers all..... :biglaugh:

oh and the cts was changed for a genuine if i remember rightly one not to long ago green top..

[smithy602179]

it could be your coolant temp sensor £35ish main dealer don't do ebay for it they not worth the plastic they made from ( experience of them myself) . its located back left of engine as you look at engine from front under the big air pipe from the air cleaner box . old ones were black but new ones are green.
good luck

[passat tdi130]

CTS was changed not long ago....

[zollaf]

if the temp gauge reads low and your heater pumps out lots of roasty hot air, then chances are the gauge is lieing. if the heater only pumps out lukewarm air, then chances are the gauge is right and the stat is opening too early.