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bobdabuilda
17-02-2010, 09:24 PM
My wife's a4 avant has been losing coolant over the past couple of weeks so much so that I have to top up the expansion tank every 3 days or so. I can't see any obvious water leakage from the rad or pipes linking the expansion tank. One thing I notice is that the engine temp gauge stays at 60 degrees and doing the 49C trick it also shows the same temp. If I leave the car idling it will rise to 68 degrees before the electric cooling fan kicks in and cools it back down to 60 degrees. Now the electric fan shouldn't kick in until well over 90 degrees so I am guessing that the temp sensor on the rad is faulty? Also I would expect the engine to be overheating due to the coolant loss but I presume it's not because of the electric fan fault?!! I need to check if the waterpump is leaking tomorrow as there doesn't appear to be any water getting into the oil or vice versa and the exhaust gases aren't super white so am hoping the head gasket is ok....

In addition to the above I have noticed a loss of braking power, alarm beeps and indicator faults (continuous fast flashing) on several occasions this month which then just disappear! After some research on the VW threads I have come across a fault on the VW passat where the plenum chamber fills with water due to blocked drain holes under the battery compartment. I have checked my car this evening (after dark) and there is about 6inches of water in there. As the brake servo is in this compartment I presume this is the cause of my dodgy brakes and electrical problems. Should there be an official AUDI recall for this problem? My car is a W reg so perhaps they will say no. Does anyone have experience of these problems and if so what was the cause /am I right in the above assumptions?

teccyjim
17-02-2010, 11:57 PM
If its your coolant temp sensor, there is a strong possibility of it producing the symptoms you have mentioned. You havent specified which engine it is, only the model, but my 2.6 has the coolant temp sensor around the back of the engine rather than on the rad where you'd expect it to be. It should throw a fault code but may not neccessarily bring on the engine management light. It will say something like 'coolant temp sensor low voltage/short to ground' or words to that effect.

Jim

bobdabuilda
18-02-2010, 10:55 AM
Thanks for the reply. I changed the green temp sender on the back of the engine recently and there does appear to be some crusting around this area which suggests that this is where the leak is coming from... There is only a crappy little circlip holding it in so not a great design feature. The engine is an APT 1.8i 20V B5 w reg a4 avant.

thebradybunch
08-03-2010, 06:55 PM
This is my first thread so apologies if it's not in the right place. I have a 1997 A4 1.8T Sport which was also losing coolant to the point where I was filling up every day. I had no obvious leaks either. I was told that the coolant flange where the temp sensor plugs into is prone to leaking. I removed the flange which is an easy job but a bit tight for space. The plastic had perished which holds the O ring in place and this is where I was losing coolant. The new flange and O rings cost £15 from an Audi dealer and after fitting......no leaks. Hope this helps.

bobdabuilda
08-03-2010, 11:34 PM
Thanks Bradybunch that certainly looks like where mine has been leaking. I changed the circlip but wonder if the whole flange needs changing as you have done. What was the part number you had please? Was it just two bolts holding it on?

thebradybunch
09-03-2010, 09:51 PM
Hello again, the part number of the flange from the invoice is 058121132 and you will also need two O rings 058121687. There is a good link which shows you with pics rather than trying to describe it. Try looking at this.
You will need a 10mm ratchet socket or spanner.

http://www.audiworld.com/tech/eng76.shtml

The Brady Bunch

Paddy27
12-03-2010, 06:59 PM
Running cold could well be a sign that it needs a new thermostat. That would not solve the fan kicking in arly though.