Pressure Testing The Cooling System

[quattroboy]

Hi Guys,

I have a mysterious coolant leak in my AAN engined S6 Auto.

I am topping up 1/2 litre every three/four weeks or so and it appears not to be a massive leak although I get a sickly hot coolant smell from under the bonnet on the left hand side as you look from the front of the car after coming back off a run. Also the S6 is not a daily driver so maybe it would be more regular topping up if it was?

I have drained and refilled the system and checked and tested the After Run Pump for condition and replaced the thermostat and sealing ring along with replacing the expansion tank and cap including checking the various hoses for splits etc. I have Checked as many of the hose connections and tightened up as many jubilee clips as I can get my socket & spanners on but nothing obvious as been spotted.

I have got the use of a Coolant System Pressure Tester and wondered if anybody knew what PSI I should pump into the Expansion Tank and how long I should leave the system pressurised and what to expect.

The leak seems to appear only when the engine is hot hence the coolant smell.

Can the Cooling System be pressure tested when hot? without ending up in A&E!

I am hoping that it won't be the Head Gasket (97K miles) as somebody suggested to me although I have clean oil and no temp gauge needle variations (always 90*)

Any information or advise gratefully received.

Cheers

Dave

[quattroboy]

Oh Cr*p it was the Head Gasket!

Just replying to my own posting............and the coolant leak was the Head Gasket and the Head is off waiting for a skim and re-assembly.

After a bit of digging the Head Gasket Failure thing seems relatively common

Anyway, here's hoping that the head isn't cracked (the head cracks towards and around the spark plug holes and the engine blows the plugs out....is what I have been told although mine haven't done as yet)............they do this a lot according to Pete Reeve at "quattro Corner", although I can't see how the plugs would come out with Coil Over Ignition, probably just lose compression instead?

£3 grand for a new VAG Head............just for the Bare Head with no valves or cams etc............Time for a 10 Valve Conversion then

Hi Guys,

I have a mysterious coolant leak in my AAN engined S6 Auto.

I am topping up 1/2 litre every three/four weeks or so and it appears not to be a massive leak although I get a sickly hot coolant smell from under the bonnet on the left hand side as you look from the front of the car after coming back off a run. Also the S6 is not a daily driver so maybe it would be more regular topping up if it was?

I have drained and refilled the system and checked and tested the After Run Pump for condition and replaced the thermostat and sealing ring along with replacing the expansion tank and cap including checking the various hoses for splits etc. I have Checked as many of the hose connections and tightened up as many jubilee clips as I can get my socket & spanners on but nothing obvious as been spotted.

I have got the use of a Coolant System Pressure Tester and wondered if anybody knew what PSI I should pump into the Expansion Tank and how long I should leave the system pressurised and what to expect.

The leak seems to appear only when the engine is hot hence the coolant smell.

Can the Cooling System be pressure tested when hot? without ending up in A&E!

I am hoping that it won't be the Head Gasket (97K miles) as somebody suggested to me although I have clean oil and no temp gauge needle variations (always 90*)

Any information or advise gratefully received.

Cheers

Dave

[RIX]

can you say 2010 euro´s in germany,and about 65 euro´s fore the head gasket.

[RIX]

and 3600 euro´s fore the bottom.(theese are the prices for aby),compleet gasket set about 240 euro´s(rs2)

RIX

[audiman]

The plugs do come out on that engine, then fire out through the coil cover. Ask Doug!!! I have seen the damage with my own eyes. Not pretty and not cheap.

[porkkis]

And 300-500 euros for a good used head. Why use new?

[quattroboy]

Holy Cr*p!

Wow,

Never would have thought that a plug would go through the cover like that.

Fingers crossed that it dosen't happen to my Big Slipper Wagon!

Dave

The plugs do come out on that engine, then fire out through the coil cover. Ask Doug!!! I have seen the damage with my own eyes. Not pretty and not cheap.

[Graham]

Resurecting an old thread here, what is the cooling system pressure before the relief valve in the cap blows off, i too have a leak where i loose about 1/2 a pint every 2-3 weeks and for the love of god i cannot find it, maybe it is so small that as soon as it weeps out it evaporates. I am making a pressure testing cap out of an old cap tomorrow and will pressurise for a few hours when cold to hopefully see an easy leak to fix, are aby head gaskets prone to leaking, it was only fitted 2 years ago, if it is the case then a skim and ARP head studs for are for me.
Cheers
Graham

[AndyP]

Cooling system pressure

Just to update this as I couldn't find an answer on here. The cooling system should be pressure tested to 1bar and the relief valve in the expansion bottle lid should open at 1.2-1.5bar. This info is from the 3B factory manual.