hi everyone,

i've recently gotten the Jetta (1.6 n/a) back on the road, for no particular reason, just felt like driving it.  this has been a problem before, but its now starting to bug me.

i'll start her up, and let her idle, so i can get some warmth reading on the temp guage on the dash, and i go, but within 5 minutes of me going the temp just drops to nil.  i guess i'm wondering if there's an correlation between engine operating temp and fuel consumption.  anyhow, my question is that is this due to a bad thermo, that's stuck wide open?  i know the guage is working properly (as far as i can tell - when i ground one of the wires, it goes 'hot'; take the sensor out and dip it in boiling water, the needle moves), and even after a 2 hour drive, i open the hood and i can put my hand on the valve cover and its not that hot...  because of the cold we're having here, it may take a while for me to actually get to replacing the thermo - i just wanted to get an second opinion to see if my keeping her running as is would negatively affect anything other than the fuel consumption.

Many thanks in advance, please excuse my babbling

chrissev,

thanks, that's kinda what i thought.  i guess i'll try to con my way into a garage to do the work.  it sure beats working outside in below freezing temps.

Cheers.

Hi guys,

as an update, it was a crappy thermostat.  man, what a pain it was to get it out.  by the way, that plastic undercarriage cover thing, is that necessary?  its falling apart, and the insulation's sucked up so much coolant and oil over the years, its real heavy and tearing itself apart.  i decided to not wait for warm weather or a garage i can con my way into...  which is probably a good thing, since i've got a lot of distance to cover this week.

bryanbryan89x, how do you mean a bad radiator?  how's it bad?  not that i can help, but just curious.

i've managed to not break the two bolts that hold the thermostat housing...  go me!  if anyone's interested, i'll try to see if this warmed engine affects the mileage at all.

one more thing (i know, i babble) i've noticed, in the few hours that i was working on the car, i unplugged it.  the temps were around freezing, and by the time i was done, it didn't want to start at all.  is the culprit the 15w-40 Rotella?  as i crank it, i see a lot of white smoke, can anyone enlighten me as to what that means?  as long as its plugged in, it'll start into the single digits, so i'm assuming its the oil...

anyhow, i'm tired.  almost 4 hrs to install a $10 part.  not to mention 2 trips to the store.  man, i suck at wrenching.

chrissev,

thanks for the info; as i've suspected.  i've got some time to kill this am, before heading down into the big city; so i think i'll get the oil changed to 0w-something, preferably something synthetic.  hopefully, eliminating that factor should ease my concerns about the starting cranks and the battery longevity.  that would have been the next to go, although i wouldn't want to spend the money, i would have gone for something like a optima red top...  i guess its better than getting stuck at somewhere without a plug.

and one more thing...  i take it the temps in your post were in *c?

Danke.

chrissev,

thanks for the info; as i've suspected.  i've got some time to kill this am, before heading down into the big city; so i think i'll get the oil changed to 0w-something, preferably something synthetic.  hopefully, eliminating that factor should ease my concerns about the starting cranks and the battery longevity.  that would have been the next to go, although i wouldn't want to spend the money, i would have gone for something like a optima red top...  i guess its better than getting stuck at somewhere without a plug.

and one more thing...  i take it the temps in your post were in *c?

Danke.

yeah temps were in celcius.  The poster who recommended checking glow plugs has a good point.  Definately the car won't start at all when it is cold outside if the glow plugs are in poor condition or not working.

bis spaeter

 The thermostat is located in the water pump, take off the spigot that goes to the bottom of the radiator and you will find it in there.  Replace the O-ring, pointy side of thermostat goes inwards.

I have to change my thermostat as it is stuck open.  I have a 1.6 N/A in a 91 golf and now I'm wondering where the thermostat is.  I thought it was at the head where the top pipes connects to the top of the rad.  Please someone advise.
Also does a new thermostat  come w/new o ring or is this a dealer item.  Will I need to use RVT?
Thanks in advance.
Out.
Greg

It's at the bottom,in the water pump housing.Remove the two bolts on the lower rad hose inlet,and it's right there.If you don't have power steering,it's easy.If you do,then you need to remove the pump and bracket.

Beware of air locks in the rad when refilling.I usually pop the upper rad hose off and refill the rad there,letting it burp till it's full.Then reconnect and fill the reservoir.

Thanks for the quick replies.  I'll get to it this weekend.  
Out.