Do I have a head gasket leak?

[Amoore]

I've recently become the owner of a 2006 Audi A3 1.6 (non fsi) petrol, and I really like the car. A lot.

Unfortunatly though, it's been one thing after another with getting it right. Recently just had to change the front lambda sensor and the thermostat but the bigger issue I'm having is I have some white smoke coming from the exhaust that smells a lot like coolant.

I'm almost at my wits end. I don't think I can afford a head gasket replacement...

Anyway, here's a video of the exhaust at idle, after a quick drive, temp is at 90c (The correct operating temp, it was running cold with old stat). What do you think? Is it a head gasket leak?

Video: https://www.youtube.com/watch?time_continue=7&v=aj2eeWvEiH4

Thanks for taking the time to read the post.

[Magnet]

Hello,

After thoroughly bleeding air out of the refilled system, is the car losing coolant, and if so how much? 

Kind regards,

Gareth.

[Amoore]

Thanks for the reply, I don't think the car is losing coolant, or at least not a noticeable amount as it was at the max line before changing the thermostat, will probably take a couple of days to see if there's a drop in the new coolant once it's sufficiently bled. 

[Magnet]

Hello A? ,

OK, we are not sure if this car is losing coolant or not. Logical thought points to no coolant loss, then no coolant mingling with the combustion, so white smoke in this case would not be due to gasket issues, but may be due to expected condensation in the exhaust .

I must own up to not having viewed your video, but I would be more interested in when/how this car exhibits white smoke from the exhaust. 

If it were mine:- I would take the car for a 10 mile fasting run on a relatively dry day, and at the end of the run - without switching off- leave the car idle for 2.minutes. Get an assistant to rev the engine to a steady 2000rpm and hold it there for at least another two minutes while you observe any smoke from the exhaust. A test under these conditions should be meaningful, and you should not see any significant white smoke. 

Having said that, we had a non Audi in long term ownership that liked pushing out a bit of white smoke during such a test, but never used a drop of coolant between annual services! 

Kind regards,

Gareth.

[Amoore]

Thanks Gareth, 

I'll be able to take it for a good run tomorrow and report back. 

[Amoore]

Steam/vapour/light smoke seems to be coming out of the exhaust even after a good 20 minute drive. I'll keep an eye on the coolant level once I'm certain it's done bleeding itself, should hopefully give some indication but it was ok before the stat change. 

Is there anything else that could cause this kind of excessive steam/vapour/light smoke from the exhaust on a fully warmed up engine?

[cliffcoggin]

Personally I place little credence on the colour or presence of exhaust smoke as a diagnostic indicator for engine condition. If you really want to be assured about the condition of rings, valves and head gasket get a compression test done or do it yourself. I believe I still have mine that I bought many years ago.

https://www.ebay.co.uk/sch/items/?_nkw=compression+tester&_sacat=&_ex_kw=&_mPrRngCbx=1&_udlo=&_udhi=&_sop=12&_fpos=&_fspt=1&_sadis=&LH_CAds=

[Magnet]

Hello A from Ireland,

We really need more specific information from you:- 

How many miles ago was this thermostat changed?

What coolant mix did you use to refill the system?

How much coolant mix are you now adding (daily?) as a result of your assumed air locks? We take it you are topping this up to the max. mark only when cold. 

Was the 'after a 20 minute run test' smoke test carried out how I suggested? If so, at what stage/stages did the white smoke appear? 

Compression test for HG issues:- 

This is likely to give you an indication of HG issues if the gasket leak is between two cylinders, in which case the values on two adjacent cylinders is likely to be lower than the others. 

Combustion to waterway leak ( which you suspect due out white smoke)? To my mind, such a leak would have to be significant before you would notice a noticeable drop in one or more cylinder compressions. 

There are more reliable tests, such as pressuring the coolant system and checking how long it's capable of retaining that pressure. There is also a 'sniff test' which looks for evidence of combustion gases in the coolant.

You could also try the following DIY test:-

Carefully remove the coolant reservoir cap when cold, to release any residual pressure. Firmly refit cap and start engine and leave it idle for 20 seconds - no more. Quickly remove cap, and you should not experience any pressure at this point.

Perhaps you could fill in all the useful detail when you come back to us.

Kind regards,

Gareth.

[Amoore]

How many miles ago was this thermostat changed?

40 miles

What coolant mix did you use to refill the system?

G12

How much coolant mix are you now adding (daily?) as a result of your assumed air locks? We take it you are topping this up to the max. mark only when cold. 

None, coolant level is now stable. 

Was the 'after a 20 minute run test' smoke test carried out how I suggested? If so, at what stage/stages did the white smoke appear? 

Not on start up at idle but starts to appear when revved and continues on when car is up operating temperature.

You could also try the following DIY test:-

Carefully remove the coolant reservoir cap when cold, to release any residual pressure. Firmly refit cap and start engine and leave it idle for 20 seconds - no more. Quickly remove cap, and you should not experience any pressure at this point.

No pressure.

-----

Thanks for taking the time to post. All of the above is leading me to believe that it might not be coolant burning after all. But that leaves me with the question of, what the heck is it? Doesn't appear to be burning oil, level is consistent. 

[Magnet]

Hello A,

Thanks for the responses. 

G12 - Unknown to me but if it's compares with the original spec and you are mixing it 50/50 then all should be well.

If you are not using any coolant, then you simply cannot be leaking any coolant into the combustion, which equals no failure of the head gasket from combustion to a waterway.

Not sure about your explanation regarding the smoke. If you would like to repeat exactly as I said and video the smoke at 2000 rpm taken over a 2 minute period.

No pressure when removing cap after 20 secs. from start up would again suggest no HGF. 

What is it? 

Rerun the video under the conditions I suggested. 

Kind regards,

Gareth. 

p.s. It's not a Rover with an Audi badge on it, is it? 

[Neil Dickinsin]

Just watched video and looks like water vapour of a cold exhaust on a cold day. 

Monitor coolant and oil level and if no change proberly worrying over nothing. 

Have you checked oil is not over filled? 

 

[Amoore]

Excessive smoking/steaming has cleared up after some good long drives with the engine getting up to temperature due to the new thermostat. Thanks for the help and the replies guys much appreciated. 

Next up is the oil consumption since it now gets up to temperate, 1L of oil per 800km. No crazy blue smoke blowing out the exhaust so I think it's got to be a leak and I think it's up the top near the filling cap as there's plenty of oil residue up there that I cleaned off since the last top up. But I'll make a new thread for that!