Brokin

2001 A6 2.7t

Hi all, finally signed up, done a bit of reading here since I acquired this joy/headache of a car in the fall of 2012. I'm a bit stumped by this problem.


The Summer Sun has been beating down (southeast pa) and My cooling system still isn't up to par. In the last two years I've replaced the leaking aux coolant pump, the oil cooler coolant hoses, (previous owner decided to keep adding oil rather than fix the leak thus rotting the hoses,) the leaking temp sensor behind engine with a green one.... (O ring had turned to jelly,) And most recently the blue temp switch in the lower radiator hose after jumping the pins on the connector and getting low and high speed operation from the behind the radiator electric fan.

I didn't have the opportunity to fully test things after replacing the switch last week. Took the time tonight and wasn't pleased. Started the car and drove till up to temp, parked the car left the engine running popped the hood. Front of rad fan is running as it did before when ac was on, low speed mostly kicking up to high as needed, behind the rad elect fan not running, fan clutch wasn't engaged so I slipped a piece of cardboard between the condenser and rad.

After a bit the temp started climbing, fan clutch engaged, front e fan went to hi speed and stayed there but nothing from the rear e fan. at 2+ bars over half on the temp gauge I pulled the cardboard and let it idle until the gauge settled to the middle. Shut it down, Slammed the hood, came inside, signed up and posted this.


Cliffs:


E fan behind rad didn't run.
Tested fan and module by jumping pins on lower rad hose fan switch connector.
Fan worked on both speeds (let run 5 min on each speed)
Replaced fan switch in lower rad hose with new unit.
Fan still doesn't run.
Will retest fan tomorrow by jumping connector pins.

Don't have vagcom, only had 1 p code for cooling system which hasn't returned since replacing the temp sensor behind the engine.

Just Me

Beside that test what makes you think the cooling system has an issue? It cant do much without much airflow ( e.g.: parked). I'm not sure i would consider that a fail. what happens when you are driving?

This was an awful weekend. My Boxster, pulling a trailer, nearly overheated int he jammed traffic around the I-80 chemical spill en route to Pocono.

Did it again when i sat chattng on pit lane - not overheat - just warning. To make the point, once i saw it and accelerated on the track for foot-to-floor flogging, all was well.

Grant
Grant

Brokin

The gauge has never shown coolant temp higher than half until this summer. (No ac last summer) At slow speeds, stop and go & at idle on hot days it can climb beyond the second bar past half. Oil temp gauge climbs with it. Maybe that fan only turns on in extreme cases, unlikely but I dunno for sure.

CRuby

Does the fan aft of the radiator work at all? You can put 12V directly to it via connectors mounted near power steering pump to test the fan, bypassing any of the sensors. If fan doesn't work then, it's not the sensors. I recently had intermitent working electric fans & it was due to worn carbon brushes in the electric motor.

Brokin

It works quite well, both speeds repeatably, but only when jumping the pins in the lower coolant hose temp switch. I have since replaced that switch and yet the fan will not run.

Funny you mention airflow, I'd have a lot more and probably more than enough if the fan would run as designed.

Airbag

well the only thing i can think of is this ... your issue is there is a block in your cooling system such as a stat or water pump failing. if the external cooling isnt working then that hose is never going to get hot enough to turn on the fan. Persoanlly from what you have written sound like your T stat is stuck closed.

But a disclaimer .. i dont have a turbo and dont know the cooling system , just an opinion based on what i am reading.

but does lead to a further question i dont have the answer to ,, at what coolant temp does that fan come on ? once you know that get in there with a laser temp checker

Brokin

Still haven't officially solved this, but I have found a temporary solution. Since fans are more effective pulling air through a heat exchanger than pushing it. I have swap spliced the power leads from the front fan to rear and vice versa. Stop and go and parked idling it barely shows past half one the gauge.