buster1

So the temperature gauge reads fine but the heater output is varying with engine speed , colder when slow/stopped and fine when at speed , time for a rad flush ? Thinking thermostat is ok since the gauge is ( or seems to be reading normal ) Any thoughts appreciated my ears are starting to bleed from the wife complaining .

Tim$2

How's the coolant level? The heater core is at the top of the coolant system so low coolant can keep the core from staying hot. I recently had a failed water pump that caused similar symptoms (due to no coolant flow). Other common causes of coolant loss are the J plug (under the thermostat) and a coolant flange on the back of the motor. Both are made of plastic and crack easily. Good luck.

buster1

No there is no coolant loss issue in this car , level always stable between min and max ........... any other thoughts ?

Axis

As mentionned by Tim check "J" plug, coolant flange, thermostat probably stuck open and temperature sensor.

Pretty sure you might have two issues, a cracked coolant flange (Hence the smell) and a thermostat stuck open (Temperature not constant). When/If changing the thermostat [ask them to] change the "J" plug while your there. Common issue on A4.

Tim$2

If you aren't losing coolant then it means the thermostat is not operating properly or the coolant isn't flowing properly. If you take that thermostat out to check it make sure to change that j plug even if it looks ok. Might as well change the common failure part while you have access to it.

Axis

^^He said in is other thread that he gets a "wif" of collant once in a while, imo craked coolant flange/or "J" plug. He woulnt lose enought to see the level drop, but enought to bring air in the system and the smell once in a while.

buster1

are the coolant flanges on the back of the head a pain to change , any tips appreciated .

//S POWER

Did you mean temp. gauge reading is 90° C? At that temp. the top rad hose should be hot to touch.

What temp. control did you set it at?


[]S POWER