My 2008 3.0 d q7 is loosing about 1litre of coolant a month. I have had the coolant system pressure tested. Nothing . No water in the oil , so where is it going?
Thanks

 

That's about 25-30 cc/day. try looking for slow leak at radiator or overflow reservoir. Also look for faulty radiator cap and/or faulty overflow reservoir cap. My first best guess would be faulty rad cap. especially if there's absolutely no coolant in engine oil or combustion chambers due to faulty head gasket.

 

Thanks for your pointers. How would I find out if there is coolant in the combustion chambers? I will check caps as per your suggestion
Carole

 

they should be able to test exhaust gases for evidence of coolant entering cylinders. If it's bad, you can see white/blue smoke in exhaust. Does car have problems starting after sitting for a while? I had similar problem years ago on another car and I'm not certain about the current testing they can actually do without removing engine header, etc. to examine head gasket. If pressure test came back okay, ask dealer mechanic for their thoughts. They should help you explore options for further testing without cost, except for actual work done on car. Replacing both caps is simplest, fastest and least expensive thing you can do. If problem then persists, you've at least eliminated those possible sources of problem and will need to explore further. You really should not be losing coolant at that rate at all. A few drops a day would be acceptable but not 20-30cc/day.

 

Thanks for this will investigate. Certainly I have had no problems with performance. To be honest I have had some weird problems with this car. Radio turning itself on , fuel filler flap refusing to open ( not good when you need fuel) . Anyway I need to get this sorted . Thanks again

 

do you mind if I ask where you're getting your car serviced? Some dealerships are better than others. There are also some very good private shops that work on Audi, if you know where to find them. I am aware of some of the good and bad of both in the GTA.

 

I get it serviced by Audi newbury in the uk.

 

I thought you were in Oxford County which is 1 hour West of Toronto. You're in the original Oxford! That's nice. Can't say I know anything about UK service. Been several times to UK and we like like it.

One last thought. Take a hygrometer reading of the coolant when it's full and again after you've lost 1 Litre. If the hygrometer reading shows a higher density, you've lost water only, likely through the rad cap. If the hygrometer reading is the same, then you've lost coolant fluid which indicates a leak somewhere (rad, hose, overflow reservoir, head gasket, etc.) If you can't do this, any garage should be able to. Good luck.

 

Brilliant . Thank you. Will sort on Monday as nobody really open here due to 1/2 inch of snow! We can't cope with weather here!

 

No exhaust gases in coolant but I did have the egr pump replaced last autumn. Could this have anything to do with it?