Bad Thermostat

[bmags88]

Hey fellow Az'rs i need some help. If i have a bad thermostat what types of issues would i start to notice? Overheating, temp gauge going nuts?? I currently have a psychotic cooling fan that decides to kick on periodically for about 5 mins at a time while it sits in the garage/driveway ultimately killing my battery. Could a bad thermostat cause this type of problem? Any help is appreciated as always!

[fapodaca]

your year car has an electronically controled thermostat. if these fail they throw fault codes......i have been seeing a few of these 1.8t's doing this.....sorry to tell you this but.
but you more than likely have a blown head gasket.........

[Audi Skate Snow]

your car is overheating, or the gauge is just going from cold to warm all crazy?

[bmags88]

Heres the deal. All thats happening is that the fan is periodically kicking on when just sitting in the driveway. The car drives fine, it's not overheating, the temp guage stays at normal operating temp. I've read that it could be a temp sensor or a fan control module. I'm just trying to figure out whats causing the fan to kick on so i've been doing thread searches on this issue and i've seen word "thermostat" a few times so I'm just trying to figure out if a bad thermostat would cause this.

[03 silverbullet]

03 Audi A4 101k

Im replacing my thermostat right now. On friday what happened to me was the engine temp went from normal, usually the middle of the temp gauge to the 3rd white line and about half way between the 3rd and the H before i could pull over.

I didnt get any CEL lights and when i popped the hood there were no broken hoses. I took the thermostat off saturday and the thing fell apart in my hinds. I already had to replace the temp sensor housing which also crumbled into pieces in my hands so i don't know why im surprised this fell apart like it did.

The car drives fine also.just picked up the new thermostat and it will be getting put in today.

If the head gasket was blow would you be able to use the VAG COM to look at miss fires or something ?

i also replaced the green temp sensor that is on the back side of the block at 98k, i got a check engine light for that though

[bmags88]

I actually have a check engine light right now. I'm wondering if its the temp sensor. If i blew a head gasket wouldn't i notice a change in driving? Would there be smoke?

[03 silverbullet]

what is the CEL for ? I think the TEMP sensor was only 45 dollars or so.

the thermostat was a nice 132.00

Smoke would be oil burning, when the head gasket blew on my friends honda you could smell coolant and it had problems idling

[bmags88]

See I don't think it'd a head gasket because it runs fine even at idle. No smoke, no overheating, no temp guage issues. All thats happening is the fan kicking on when the engine os off. CEL, wel i just got my VAG Com a week ago and haven't tried it. I'm trying to actually learn how to use it. I really just need to hook it up and runa full scan and get the fault codes right?

[03 silverbullet]

HA i got mine about 2 weeks ago and am learning how to play with it too.

I would try running the Auto scan the second button choice or if u can take it to Autozone or advance auto they have the OBD II scanners u can use for free

[Audi Skate Snow]

Its not a head gasket if your not overheating and loosing coolant.

2 things.

Thermostat
or
Coolant temp sensor.

the code your getting is probably 1296 (iirc) which is a cooling system CEL.

[bmags88]

HA i got mine about 2 weeks ago and am learning how to play with it too.

I would try running the Auto scan the second button choice or if u can take it to Autozone or advance auto they have the OBD II scanners u can use for free

Nice, i'm gonna try it out tonight. If not i can drive it down to Autozone. thanks!

[bmags88]

Its not a head gasket if your not overheating and loosing coolant.

2 things.

Thermostat
or
Coolant temp sensor.

the code your getting is probably 1296 (iirc) which is a cooling system CEL.

I'm glad !! I read "blown head gasket" and i threw up all over the floor. The 1296 code code doesn't really tell me shit right? It doesn't narrow it down to either one right?

[03 silverbullet]

how many miles are on your car ?

After i replaced the green temp sensor i think it was like 3 months later the black housing it was in started to leak and broke apart.

I have 100k on mine if u are around that u might as well just do the sensor and the black housing at the same time.

If u end up just doing the sensor there is a write up for it on here, well there are write ups for both on here.

Here is a tip. You ever buy paint at Lowes or Homedepot ? they have those little paint can openers ( http://www.flexiblesanders.co.uk/pro...ner_bigpic.jpg )

this thing worked better then ramming a screw driver down there to get the black clip back into place because the end is hooked just enough. if u read the write up you will know what i am talking about.

[Audi Skate Snow]

I'm glad !! I read "blown head gasket" and i threw up all over the floor. The 1296 code code doesn't really tell me shit right? It doesn't narrow it down to either one right?

ahaha yea if it was the head gasket, you would overheat and be loosing coolant.

The code doesnt narrow the two down... but here is what you can do.

this might be helpful

http://www.audizine.com/forum/showth...ght=thermostat

[bmags88]

Thanks for the thread link. It was very helpful.

[Elliott]

Was this ever resolved? I'm having similar issues.

-Erratic temp guage
-Muddy coolant
-No heat
-But flawless idle, no smoking, etc.

[gt6974a]

Was this ever resolved? I'm having similar issues.

-Erratic temp guage
-Muddy coolant
-No heat
-But flawless idle, no smoking, etc.

That's exactly what happened to mine a couple weeks ago, replaced sensor first, but turned out to be thermostat

[dmcleer]

I have an overheating issue on my 2002 1.8T. I was driving it and suddenly the temp gauge went all the way to the right and the big red coolant warning came on. AS quickly as it did that it went back to the center. This continued as I slowly limped the car home. I thought it was the thermostat, but the guy at my shop said more likely than not it was the temp sensor, which he replaced. I have the car back now, and when I turn it on and let it warm up it runs as normal with the gauge right in the center. I popped the bleeder screw on the hard pipe and coolant comes out of it. I did notice that while the car was running i would get some bubbles in the expansion tank with the cap off. I have not tried to pull the hose by the heater box yet. I am not sure where that is. Also now I have smoke coming out of my tailpipes. This is a new development. When I run the engine to around 2k rpm the temp gauge starts to climb. As soon as I let it come back to idle the gauge goes right back to the center. When I feel the radiator hoses the top one, coming from the hard pipe is hot, and I have no problem squeezing it, and the two hoses on the bottom of the radiator are cool, and again I can squeeze them with no problem, and feel no restriction, like there is no water in any of them. I have roughly 130k miles and never replaced the water pump, could it be gone? If so wouldn't the car overheat even at idle? Does the smoke mean the head gasket is blown?

HELP!