During start up- rough lide/misfire

[RS6NOR]

You mean 1700 EUR for a head gasket and 1700 EUR for a cylinder head plus labor cost on top of that? That's insane, especially the gasket price...
I would look for someone selling an RS6 engine only or for someone breaking an RS6 for parts.
Have you got a second car to use in the meantime?
Man, sorry to hear your problems.

Maybe my wording was probably not the best. The cost per cylinder head was 1700 EUR. I think a complete head gasket kit is around 200 EUR.

The shop has quoted me for 30 hours of labour ( include engine pull) 600 pound for rebuild and pressure test of cylinder heads. With Noewegian labour cost the total cost is close to 5000 EUR. Note! This assumes that the head is not cracked behind repair.

To bad the passanger wessel to and from norway an uk has stopped running. Doing it in the UK would probably save me some money.

[RS6NOR]

Aren't you blowing white smoke? Losing a litre without driving the car is a huge amount.

I drive the car daily and i was touring europe some weeks ago so the amount of water has ben use over 2-3 months. There are no white smoke when driving. There is slightly more smoke from the right pipe ( seen from behind) during statup and drve off, but it ends just after 100m of driving. And the difference is not significant and it is not a distinct white smoke.

[RS6NOR]

Also, how can it be dripping inside the cylinder freely but coolant system pressure test shows normal?

I see your point. If there is communication between the coolant ciruit and the cylinder you should think that a compression test would capture that. The shop says that the leaks probably is so small that it is only seeping throuhgh some droplets every night. With such a small leak they are not certain that you would capture it on a compression test.

I guess Grizz would have some good input to this issue...?

[Shoppinit]

Yeah, but he won't be back.

I would want stronger proof that the there is a problem with the head before committing to pulling it.

I know head gasket failures are always a bit weird in terms of the symptoms but I am having difficulty imagining water leaking into the cylinder under low pressure, but there being no combustion products in the coolant. Sure, you might not see a tiny leak on a compression test, but driving the car? The pressures involved are waaay higher.

I had exactly that failure recently on my Golf. In the end, I had exhaust coming out of the expansion tank (which was quite highly pressurised).

[RS6NOR]

Yeah, but he won't be back.

I would want stronger proof that the there is a problem with the head before committing to pulling it.

I know head gasket failures are always a bit weird in terms of the symptoms but I am having difficulty imagining water leaking into the cylinder under low pressure, but there being no combustion products in the coolant. Sure, you might not see a tiny leak on a compression test, but driving the car? The pressures involved are waaay higher.

I had exactly that failure recently on my Golf. In the end, I had exhaust coming out of the expansion tank (which was quite highly pressurised).

I know, it is not straight forward... They have checked the coolant fluid for traces of hydrocabons, but they did not find anything.

[RS6NOR]

Another ting i have tought about is: how is the engine detecting a misfire? What is the logic behing a confirmed misfire on a cylinder?

[Shoppinit]

The misfires are detected by the ECU recognising extremely slight rotational variations of the crankshaft. If there is a misfire the crankposition will deviate from a normal.

I still think that you should definitely eliminate the coil packs and injectors. It's a no cost test and definitely eliminates them.

[grizz]

Leave the car over night , Then before its started pull all the plugs and check them for moisture ....

We've had a lot with head gasket failure ..Even when stripped the gasket looks perfect ..

[RS6NOR]

Leave the car over night , Then before its started pull all the plugs and check them for moisture ....

We've had a lot with head gasket failure ..Even when stripped the gasket looks perfect ..

Thanks for your reply Grizz it is very much appriciated!

Today when they prepared for the compression test they removed the sparkplugs and they entered the cylinders with a camera. Cylinder 3 was moist inside, while all the others was dry. They also said the cylinder looked "cleaner" inside and the plug was cleaner than the others. They where quite convinced that there is a leak through the gasket or a crack in the cylinder head.

[bilko1]

Today when they prepared for the compression test they removed the sparkplugs and they entered the cylinders with a camera. Cylinder 3 was moist inside, while all the others was dry. They also said the cylinder looked "cleaner" inside and the plug was cleaner than the others. They where quite convinced that there is a leak through the gasket or a crack in the cylinder head.

That's what i told you to do a few pages back.

[RS6NOR]

Today when they prepared for the compression test they removed the sparkplugs and they entered the cylinders with a camera. Cylinder 3 was moist inside, while all the others was dry. They also said the cylinder looked "cleaner" inside and the plug was cleaner than the others. They where quite convinced that there is a leak through the gasket or a crack in the cylinder head.

That's what i told you to do a few pages back.

I know and thats why they did it. So thanks for your advice

[adsgreen]

Another ting i have tought about is: how is the engine detecting a misfire? What is the logic behing a confirmed misfire on a cylinder?

The logic varies but as Shop says the ECU "knows" when to expect an acceleration of the crankshaft from the crankshaft position sensor and if there isn't one or it's at the an unexpected time it can detect it.
The issue is that it can't detect it at all times so there are windows that define when the misfire detection is actually running.
Usually it is something like "steady speed and throttle for 10 seconds betwenn 20 and 40 mph" or similar. In this timeframe the ECU will count misses and to a degree some are expected (especially when cold) so one or two will not be recorded as a misfire. If the number of misses exceed a given threshold in the window timeframe then you'll get the MIL on. If the number of misses is higher than a second more severe threshold then the MIL will flash as there is a risk of damaging or overheating the cats.

But anyway - this is why you can have a misfire not picked up by the car.

[Shoppinit]

The underlying question is, can the ECU get it wrong in terms of which cylinder is misfiring. Anecdotal evidence suggests that it can.

[Ryan_Pestell]

yes it can! my issue proved that.

[Shoppinit]

You were the evidence I was referring to.