A4 3.0 Petrol - head gasket? Hydrocarbons found in water tank... :-(

**jullio** · 24-03-2015,08:16 PM

Greeting all,

I need some help...

I have a 2004 A4 Quattro sport with the 3.0 v6 lump init and 90k... It has for a while been using a little water and I have noticed a bit more steam from the two exhausts in the morning... Took it to a garage and when they took the water filler cap off there was clearly a build up of pressure... So put an HC anaylizer in the water tank opening and it was reading circa 10 - 20 PPM in HC....

All signs therefore lead to a Head gasket and on both cylnder banks. Does anyone have a different perspective and if not a clue how long may I have before it goes critical given the relativley low ppm for the size of engine.... A head gasket change is just horendous from a cost perspective given the age / value of the car and complexity of the engine.....

Very much apreciate any views to help forming a view before I decide my next move.......

Cheers,

Chris

**mikeybutch** · 24-03-2015,08:52 PM

Wouldn't it be strange that both have aleak?How much coolant is it losing and at what rate?Cant see why it would be related to pressure in the system which is normal when warming up.I am on my 2nd 2.5tdi and I know the feeling of having big bills lurking which one day wont be worth risking but so far have been lucky others haven't.My last one always used a little coolant and lots of white exhaust but it didn't get any worse for 3ys and always ran well.I never investigated perhaps thinking it was usual until realising this one doesn't do either so maybe got away with it.Is a compression test feasible ? Wouldn't that narrow it down?Can oil get in the coolant from other sources?Any mayo in the cap?I would expect some

**jullio** · 24-03-2015,09:09 PM

Originally Posted by mikeybutch

Wouldn't it be strange that both have aleak?How much coolant is it losing and at what rate?Cant see why it would be related to pressure in the system which is normal when warming up.I am on my 2nd 2.5tdi and I know the feeling of having big bills lurking which one day wont be worth risking but so far have been lucky others haven't.My last one always used a little coolant and lots of white exhaust but it didn't get any worse for 3ys and always ran well.I never investigated perhaps thinking it was usual until realising this one doesn't do either so maybe got away with it.Is a compression test feasible ? Wouldn't that narrow it down?Can oil get in the coolant from other sources?Any mayo in the cap?I would expect some

Hi and many thanks in replying.....

I think every month and a bit I am putting water from the low to max point on the coolant bottle. Not thought of a compression test and yes that would help narrow things down but fact remains that HCs are in the coolant. There's a tad of mayo on the dipstick but not in the cap.....Surely the pressure in the coolant bottle after 20 mins running would dictate a cylinder leak but I agree is that one cylinder of more per bank...

you have given me some confidence in not panicking and maybe just leave it... but............................................... ..................

**mikeybutch** · 25-03-2015,11:26 AM

All pressurised cooling systems do this that's why they get a higher boiling point.Thats a little too much coolant loss but are you sure theres not just a leak somewhere?I think I would go for a comp test cos that shows if you have any low cylinders and I would research other ways oil can get into the coolant.Must say that any mayo isn't right but, if its not on the cap, again it may be by some other means less serious than you fear.I would be happy using the car but not for long trips until you can sort it

**jullio** · 25-03-2015,08:27 PM

Thanks Mikey... whilst I am an engineer I am no mechanic for circumstances such as these.. The comp test is booked in Friday so the favourable result would be no decline in compression from OEM spec... is it right to assume the 10 - 20 ppm of HC at the coolant bottle could relate to a non head gaskets / cyl issue?

Six months ago I had the cam belt done and also crank and cams seals done, the latter was required as oil leaks were found during the C/B change at a cost of £1.1k :-(. The car also sufferd an immediate oil from the work which was rectified shortly after. Surely this work should have bugger all do with water / oil barriers?>!

Apreciate the guidance in forming a decission which may or may not cost me a shed load of cash in selling of curing...

Chris

**arvydasxx** · 25-03-2015,08:54 PM

You just scared me as well, because I have same car as you have and it uses a bit of coolant and it steams a lot through exhaust, I have to put about 0,3 l of coolant for every 1000 miles, it also has quite a lot of pressure at expansion tank.

**mikeybutch** · 25-03-2015,09:32 PM

Hope this doesn't discourage but I have no technical training being an ex banker and lawyer of sorts but I have been DIY motoring for a long time albeit slowly now.I have defo heard of oil contamination from other sources and would seek advice also get an allround check for coolant leak.Having looked at a few headgaskets( in my early days) I think the comp test will tell you if there is a leak assuming the piston rings are in good nick.If you are worried about coolant being burned off that might not be the same as a blow between the oil and coolant systems either in the h/gasket or somewhere else.Cant see why the work you had done would be relevant unless some oil got dropped in the coolant!!Perhaps this new comment might indicate that these symptoms are characteristic of some or at least not uncommon?After all a blown headgasket usually means poor performance and early demise if not sorted.Another crude test is to disconnect each cylinder in turn and see if any one makes a bigger difference than the others , arvydasxx don't think you should worry if the coolant loss is steady and doesn't worsen.Again you may have a small leak and the system is highly pressurised and no way should you remove the cap when hot.There is a lot of vapour on cold days before the engine is up to temp ;if it persists then I would be concerned

**arvydasxx** · 25-03-2015,09:42 PM

Other than coolant loss and a bit of steam car runs nice and smooth, I have had a slight misfire on cylinder 5 for a week or two on high rpm but it disappeared and never been back..