View Full Version : Engine Temperature Dropping on Long Downhills
a4dc89
11-30-2011, 11:26 AM
So in the first 10-15 mintues of having my car warmed up, on long downhills the temperature drops from the middle of the gauge. Could this be the thermostat?
Homer
11-30-2011, 11:47 AM
That's normal. During engine braking, the injectors are shut off, there is no heat input into the engine.
Coming out of the rockies I had the temp gauge drop to 1/4.
Charles.waite
11-30-2011, 12:02 PM
If it gets colder on uphills then it would be your thermostat. Just drove from Seattle to Whitefish, MT and going up the passes my temp dropped to 3/8 to 1/4 on the long uphills. The thermostat has been on the must replace list for a little while now.
Downhill I don't know, though the guys above seem to think its normal, so it probably is.
DoThisMyWay
11-30-2011, 12:12 PM
It's definitely not normal. I was told the same as the second poster stated but the symptoms got worse over time. I changed out the tstat and the needle now stays dead center no matter what the outside temp is, costing downhill, down shifting or sitting still at idle. Your stat is stuck open and it'll get worse over time.
Tanner
11-30-2011, 12:17 PM
Not normal, even in -20C and when I coast down hills, the coolant temp stays pretty steady at 90C. Change the tstat as others have mentioned. It'll get worse to the point that you'll barely have any heat in the winter.
As I looked back on that repair job the other day, i noticed in the details on the bill, they did "diagnostic and troubleshooting". Wonder how much labour was involved in that as I just wanted them to change the tstat.....
DoThisMyWay
11-30-2011, 12:39 PM
It took me 3 hours and I'm no mechanic. It's great that the front end doesn't have to come off too access the tstat but it's sure buried under the alternator and a bunch of other crap. When I took my car in for the timing belt, the tech said replacing the tsat was a separate job at $300, so that's probably 2.5 hours labor since I already had the replacement part. He also ran diagnostics and said the over cooling issue could be the coolant temp sensor or fan control module, which it wasn't.
Stewy
11-30-2011, 02:40 PM
Definitely not normal. As stated above, regarding of ambient temp, load, etc...the needle should stay pretty damn close to center. I would swap out the thermostat.
Not normal, even in -20C and when I coast down hills, the coolant temp stays pretty steady at 90C.
Same, and I do a lot of winter driving in the cold up and down mountains... always dead center.
a4dc89
11-30-2011, 04:08 PM
Same, and I do a lot of winter driving in the cold up and down mountains... always dead center.
Thanks, looks like im gonna have to replace the thermostat :/
Thanks, looks like im gonna have to replace the thermostat :/
Get back here with your result after changing thermostat. Cause mine is the same and audi said it is normal if it goes down driving downhill. Waiting your result.
The thermostat on your vehicle controls the flow of coolant based on temperature. When you just start your engine, the thermostat remains closed to accelerate the warm up process. After a few minutes, it opens up to allow the warm fluid to flow. If your vehicle is overheating but not blowing warm air from the heater, the problem is more than likely your thermostat.
If the thermostat gets stuck closed, it allows no fluid to flow and ends up overheating the coolant already in the engine. To fix this problem and get your vehicle's heat restored, replace your thermostat.
carguy138
12-11-2011, 04:52 AM
How many people here say that this problem is normal have a FMIC? My car never did this until I put one on.
b7a4GT30
12-11-2011, 08:14 AM
i had the same problem in my S4, the culpurate was that the T-stat was stuck open. Replace that and your good to go!
Charles.waite
12-11-2011, 10:13 AM
How many people here say that this problem is normal have a FMIC? My car never did this until I put one on.
Not normal. The FMIC shouldn't affect the cooling system at all. All it does is lower the intake Air Temps. If anything, since a FMIC blocks the radiator, you should see the cooling systems working harder to keep the engine from overheating.
Just so everyone is clear, THIS IS NOT NORMAL!
Good god....
a4dc89
12-12-2011, 07:19 AM
How hard is it to replace the T-stat yourself? I'm kinda sick of the expensive repairs on this car and I'd rather DIY
Tanner
12-12-2011, 07:29 AM
There's a thread on how to replace the t-stat...
http://www.audizine.com/forum/showthread.php/461389-Thermostat-Diagnosis-Replacement-Technical-Questions
Charles.waite
12-12-2011, 02:06 PM
^^ That thread, that I started, is sort of a work in progress. At this point its more of an outline of what is going to take place when I do replace the thermostat. A few people have dropped in to outline the process. Hopefully this weekend I'll be able to actually replace the damn thing and get some decent pictures to post up.