VW valve fail

[Mick D]

its the inlet valve or ex ?

being smaller, I would expect inlet valve. meaning it should be well shut when a combustion event takes place.

It is the exhaust valve that is burnt out.
I have never seen an engine that has larger exhaust than inlet valves.
Its all about getting air in. Some engines even use two inlets and only one exhaust.
Occasionally inlet valves can fail, but super unusual that they fail to this extent.
This is the type of failure that is mainly reserved for exhaust valves.

[fred99999au]

All I'll say is that it is 11:30pm, much wine has been drunk and I stand corrected.

[Mick D]

I concur Fred, good night mate.

[Mick D]

The mechanic that tore it down is the one privy to all the clues.
That chamber carbon is soaked with fuel whilst still hot, the vehicle was driven on with the injector still working after this pot gave up.
a pitty the pic doesn't include the other pots for comparison.
There was no fuel starvation or air in this fuel system.

If it were going to burn a valve, the most likely place is along this red line. It is the line that hot spots occur along and for good reason.


If I were tearing down? The next thing I would do would be to scrape the carbon of the valves and head, for the sake of measuring valve recession.
Use a straight edge accross the head and feeler gauges between the rule and valve head to calculate recession.
The head of these valves should be sitting up near level with the head surface, like one of the inlets still seems to be. It may be an optical illusion though? That does not look to be the case here but. Measurement? The more an exhaust valve recedes,,the hotter it runs and another of a few factors that the stage was being set for this burn out failure.

For only 122,000 klms, only 76,000 miles, the exhaust valves already sunk in this much, spells nothing short of complete and utter junk. Don't forget a hell of a lot of plain old Commodore and Ford taxis did 600,000. Then another 400,000 after a head and de-coke job. A million Klms, around town hard flog miles, on dry old LPG. This thing only 122,000 and valves already sinking=JUNK.

Off the track for a moment,,,,
A good way to speculate what the phony software is about,,,, get a dyno certificate before the fix and then another after. Compare. A simple reason for cheating on emissions testing might be for the sake of dazzling your audience and outperforming the opposition?
 

[80-85 husky]

I thought the whole emissions scam was about gaining approval to sell the cars in various countries without doing the hard work to get them to pass.

[shelpi]

its the inlet valve or ex ?

being smaller, I would expect inlet valve. meaning it should be well shut when a combustion event takes place.

It is the exhaust valve that is burnt out.
my point exactly, so narrows down the prognossis 
I have never seen an engine that has larger exhaust than inlet valves.
Its all about getting air in. Some engines even use two inlets and only one exhaust.
Occasionally inlet valves can fail, but super unusual that they fail to this extent.
This is the type of failure that is mainly reserved for exhaust valves.

[Mick D]

I thought the whole emissions scam was about gaining approval to sell the cars in various countries without doing the hard work to get them to pass.

So what is the hard work? that would have gained approval without cheating and lying in the first place.
VW are now saying that the fix only requires one model to have a sensor installed then a software amendment.
And that all other effected models are software amendments only.

The diesel engines that I have done extensive work on(80+ complete overhauls+a huge amount of servicing)
Are slower revving engines and that is one reason why they run 24/7 x 365 x numerous years, whilst being totally dependable with very slow wear rates. VW and Audi have turned these dependable Clydesdales into high revving
high performance engines that have dazzled the masses.
Pardon me from being suspicious, but what is the real reason they would put the engine into a different run mode when it recognizes it is being emission tested? And at what sacrifice and true cost is that less polluting test mode?

I said,

A good way to speculate what the phony software is about,,,, get a dyno certificate before the fix and then another after. Compare. A simple reason for cheating on emissions testing might be for the sake of dazzling your audience and outperforming the opposition?

To speculate, to compare, why did they really falsify? When they could have just run the vehicle in a continuous compliant mode all along?

If it is as simple a fix as a software amendment to get the right emissions readings out of the engines exhaust, then why was it not done in the first place and what was the true trade off?
The cost has to be met "some where", or there would have been no point to the deception!
Hard to believe that it will not be some measure of performance to be paid.

A certified dyno chart before and after would shine the truth on those that have proven beyond any reasonable doubt that "they cannot be trusted to tell the truth" unless held to account.
 

[Mick D]

In my training, I remember a teacher saying that the "wear rate" increases proprtionally as engine RPM increases. I cannot remember the exact formula? But I do remember that part of the mathematical formula was
To "cube" the wear rate per every certain amount of RPM increase figure? Keep the revs going up and see what happens.

I am saying this looks like a large amount of wear(valve recession) for an engine that has only done 122,000 kilometers.

I am suggesting they are a long way from making a higher revving, high performance diesel worthy of the sustained mechanical reliability and more to the point durability that we once took for granted when talking Diesel engines.

I am saying that a dyno may be the way to shine the spotlight of honesty on those who are not.

Are we that gullible as a world population that we would simply believe again those who are unbelievable?
 Please  

[Nathan S]

I agree with Mick D, except I don't think the valves have recessed (much) from new.

The angled area around the valve is noticeably larger in diameter than the diameter of the valve head, - and this is true of all four valves. For whatever reason, VW designed the motor like that.

[pokey]

When you put it that way mick i must agree. all that oil has disguised just how hot that cylinder was. the glow plug is also missing so we cant check that either. Hmmm sell the VW for scrap and buy an aircooled two stroke.

[Lozza]

Whats a valve anyway ? 

[evo550]

I thought the whole emissions scam was about gaining approval to sell the cars in various countries without doing the hard work to get them to pass.

They had a high performance motor that couldn't meet emissions standards.  VW set it up so the computer (motor) would  provide acceptable emission levels while being tested (in neutral in a workshop) and then recognise when the car was on the road and it would switch off its emission devices and provide performance, but it couldn't meet emission standards then.

[80-85 husky]

clever little germans....just as the aussies would have done....

[shelpi]

Whats a valve anyway ? 

you know... reed valve

[skypig]

Some interesting information and speculation (and quite frankly some pretty average 2 stroke jokes  - I'll get the mechanic to check the powerband is not stretched  )

Unfortunately, this has happened while my mate and his young family are on the other side of the country, with no transport home! I can't help/speak to the mechanic/look at some of the suggestions above.

I still think it's an odd looking failure, but some think, and I'm not experienced enough to argue, that it's a straight forward "burnt valve"?

One thing that is beyond dispute: It shouldn't fail in family van, driven and maintained "normally" by a family at 122 000km.
I wonder if VW are interested in contributing to a solution? Pathetic if they aren't.

Now I'm going to play "Smoke on the water" on some reed valves.....