PDA

View Full Version : Coolant temp slightly above normal....what's the cause?



Chuckdee
03-26-2012, 10:49 AM
So I made a previous thread about this issue but after ruling out every possible cause...I still don't know what can make the coolant temp go slightly above normal. I did numerous coolant flushes, flushed the heater core, was about to replace the water pump I noticed the water pump was already replaced by the PO with a working metal one, checked the radiator for flow and it's still flowing well, the electric fan is working, replaced the radiator cap with another one, replaced the t-stat and coolant temperature sensor. Also checked around the head for any leaks and I don't see any, oil color/level is still fine and bled the system. And it still tips over 1/2 in between the 12 o clock to 1 o clock notches sometimes while sitting idle. When driving it's fine. It sounds like I'm going crazy but I don't know if it's a big deal or not.

Is this something I should worry about? could it be something else that would make it run a tad bit hot?


I should also add I'm throwing a CEL code for timing (forgot which one is it) so I need to replace the cam chain tensoner. Could that be it?

Mr.Audi
03-26-2012, 10:57 AM
i'd think water pump or fans by what ive read.

i had a water pump go bad once on a jetta i had and it would be hot when idle or not moving... but once moving it would cool back down or return to "normal"

Chuckdee
03-26-2012, 11:32 AM
i'd think water pump or fans by what ive read.

i had a water pump go bad once on a jetta i had and it would be hot when idle or not moving... but once moving it would cool back down or return to "normal"

I thought so too, but the water pump has the metal fins and it still looks new and intact.

jonnytrack
03-26-2012, 11:38 AM
My 01 TT had the fuel gauge and temp gauge move about 1/8" to the right so it looked like the temp was a little high and the gas a little higher. Don't know how it happened but didn't bother me.

walky_talky20
03-26-2012, 11:47 AM
I'd make sure you fans are working. Jump the fan switch and check both speeds. Also, be sure that it is actually overheating. Watch the coolant temp in vag-com (or on the HVAC display).

Chuckdee
03-26-2012, 01:28 PM
I'd make sure you fans are working. Jump the fan switch and check both speeds. Also, be sure that it is actually overheating. Watch the coolant temp in vag-com (or on the HVAC display).

I would watch for it on the Hvac but 90% of the screen is gone :( and the electric and clutch fans are working properly. The clutch for the fan isn't weak at all (did a test) is constantly on due to the fan it has no freon.

walky_talky20
03-26-2012, 02:27 PM
is constantly on due to the fan it has no freon.

I didn't really understand this part. Please clarify.

Chuckdee
03-26-2012, 04:13 PM
I didn't really understand this part. Please clarify.

I heard the Electric fan stays on whenever there's low pressure in the a/c lines, and I haven't added freon in the system yet. Or is there another reason why it would stay on?

AudiNFS
03-26-2012, 04:20 PM
I heard the Electric fan stays on whenever there's low pressure in the a/c lines, and I haven't added freon in the system yet. Or is there another reason why it would stay on?

I'm pretty sure the electric fan only comes on when the coolant reaches a certain temperature, like 243 degrees F (I think, could be completely wrong.) What's the condition of the radiator? Unlikely but that could be an issue.

jonnytrack
03-26-2012, 05:12 PM
Right about the 243 degrees, wrong about it staying on with low pressure.

Chuckdee
03-26-2012, 06:06 PM
It's ALWAYS on, as in even from a cold start before even starting and the key turns to ignition, the fan comes on.

AudiNFS
03-26-2012, 06:18 PM
It's ALWAYS on, as in even from a cold start before even starting and the key turns to ignition, the fan comes on.

That would be the mechanical fan. The electrical fan is the one next to it.

Chuckdee
03-26-2012, 06:27 PM
That would be the mechanical fan. The electrical fan is the one next to it.


:facepalm: I know what both looks like and I know what I'm talking about. Before starting the car the ELECTRIC fan kicks on, even at a cold start.

jonnytrack
03-26-2012, 06:32 PM
My 2000 A6 2.8 electric fan runs when I first start up IF I am using the compressor e.g: A/C or Defog or even sometimes heat without economy mode on. But in your case it certainly sounds like a temp sensor issue so fix your HVAC display or Vag-Com

mobilesuit818
03-27-2012, 12:07 AM
I had a similar issue with my 99 B5 1.8t. I was literally chasing demons till I used one of the those thermo guns to confirm the temp....and it was within tolerance even though my temp gauge said something different...i ended changing the cluster and voila....some temp gauges get out of sync for some odd reason...

Chuckdee
03-27-2012, 07:49 AM
I had a similar issue with my 99 B5 1.8t. I was literally chasing demons till I used one of the those thermo guns to confirm the temp....and it was within tolerance even though my temp gauge said something different...i ended changing the cluster and voila....some temp gauges get out of sync for some odd reason...

This is an interesting idea but a bit of me is thinking of giving up and living with the issue. It isn't critical, just a tad bit annoying. it only tilts between the 12-1 o' clock position SOMETIMES but everything else seems to be fine. I heard over advanced or over retarded timing can also be the culprit?

Aragorn
03-30-2012, 12:30 AM
Connect VAGCOM and view the ACTUAL temperature as reported by the sensor.

Matt Devo
04-12-2015, 08:10 PM
necro-bumping this since I'm having the same issue on a 98.5 B5 1.8T I recently acquired. The cluster coolant temp reads 1 tick to the right of center when at normal operating temp. VCDS reports the coolant temp fluctuating between 91-95C. VCDS output test shows the gauge sweeping properly and coming to rest at center. What is the normal operating temp on a B5? I know on my B6 it's ~100C, but not sure on an AEB B5

thanks!