Low Oil Temp But High Coolant Temp???

[tomrat]

Hi Guys,

Coming into my first Winter here in Aus with my Stg 1 S4 and noticed something a bit funny the last few morning on my way to work.

My car is struggling to get any oil temp after a 40 min drive, as in the temp is so cold it won't even register on the dash (<60°C), however my water temp is higher than usual at 100°C, when it is usually 90°C.

I've never had the water temp go over 90°C, even when thrashing it in 35°C ambient conditions, but now with 10°C ambient conditions it's running hot?

The fan is also running after I turn off the car, which it usually only ever does after I've driven it hard, I'm so confused as to why this is happening, usually when the coolant gets hot, so does the water, but now I'm getting cold oil but hot coolant?

Anyone experienced this before, any ideas why this could be occuring?

Thanks!
Tom

[XSWG]

Which tune are you running the stage 1 file for? The fan seems like an issue that 034 fixed a few revisions ago with the fan being on max to try and reach their designated oil Temps but that was calibrated a while back so you may just need to update.

As for the oil temp 60 Celsius is about 140-145 for us Americans. Which is really low and might be tied to the first recommendation I made. The coolant temp could be your thermostat making its exit, there have been a few thermostat failures on this platform.

Sent from my SM-N986U using Tapatalk

[Smac770]

Maybe the oil temp sensor is failed. Have you logged both the G266 oil temp sensor value and the G8 oil temp sensor value to see if the issue is specific to one of the sensors? G266 is the thermal oil level sensor in the oil pan. The G8 sits under the oil cooler or such.

Maybe the oil cooler is failed. The oil cooler has a thermostat inside it. Maybe it's stuck open and too much oil is passing through the cooling channels to the coolant. The thermostat is not supposed to even open to pass oil to the cooler until the oil hits 110°C. This is a passive device, just like a coolant thermostat; failure of one of the temp sensors would not impact its operation.

Have you scanned for DTCs to see if anything is present?

[tomrat]

Which tune are you running the stage 1 file for? The fan seems like an issue that 034 fixed a few revisions ago with the fan being on max to try and reach their designated oil Temps but that was calibrated a while back so you may just need to update.

As for the oil temp 60 Celsius is about 140-145 for us Americans. Which is really low and might be tied to the first recommendation I made. The coolant temp could be your thermostat making its exit, there have been a few thermostat failures on this platform.

Sent from my SM-N986U using Tapatalk

Hey mate! Yep on the latest revision of the 034 tune so don't think it's that. I've read about the thermostat failures, the issue has since gone away which in some ways is even more worrying haha, I'll keep an eyes on things, thanks!

[tomrat]

Maybe the oil temp sensor is failed. Have you logged both the G266 oil temp sensor value and the G8 oil temp sensor value to see if the issue is specific to one of the sensors? G266 is the thermal oil level sensor in the oil pan. The G8 sits under the oil cooler or such.

Maybe the oil cooler is failed. The oil cooler has a thermostat inside it. Maybe it's stuck open and too much oil is passing through the cooling channels to the coolant. The thermostat is not supposed to even open to pass oil to the cooler until the oil hits 110°C. This is a passive device, just like a coolant thermostat; failure of one of the temp sensors would not impact its operation.

Have you scanned for DTCs to see if anything is present?

Thanks for the heads up. The issue has since gone away but these are some great tips for if it arises again, appreciate the info!

[slws4]

Hey mate! Yep on the latest revision of the 034 tune so don't think it's that. I've read about the thermostat failures, the issue has since gone away which in some ways is even more worrying haha, I'll keep an eyes on things, thanks!

Im going to say it could be the tune, unreleated but on my EPL stage 2 antilag file, it caused the car to display a higher than normal coolant temp and at one point (after somepulls) i thought it was overheating. Switching backt o OEM the problem went away. Odd. I know my thermastat is not on its way out as i just had it serviced at the dealer, the waterpump and thermostat was both changed out. So i know its fine.

[tomrat]

For those following along at home. This issue kept arising until eventually the car would put the radiator fans on full, even on a cold start. Car threw codes: P01E400 and P017B00. Tech diagnosed either bad thermostat, or bad thermostat sensor (it's all one unit.) Replaced at a cost of $1200AUD inc. labour.

My mechanic said the local Audi dealer had a concerning amount of stock of EA839 thermostats, which tells you all you need to know.