On Wed, 23 Jun 2010 13:31:42 +0100, "David Skelton"
> wrote:

>
>>>>>Recirculated exhaust gasses containing crankcase oil vapours, over time clogging up
>>>>>the
>>>>>EGR valve and building up on the flaps.
>>>>
>>>> No..in a diesel, oil in the exhaust will be entirely made up of
>>>> unburnt diesel not engine oil. Any tiny amounts of engine oil will be
>>>> completely and massively irrelevant compared to the unburnt diesel oil
>>>> quantities.
>>>
>>>No, you are wrong...
>>>
>>>Engine oil enters the combustion process from worn rings, worn valve stem oil seals,
>>>the
>>>PCV system, thrashing the engine from cold, and from damaged / worn turbo seals
>>>especially in engines run on the incorrect oil spec.
>>>This oil burns differently to diesel oil and leaves carbon deposits behind.
>>
>> I disagree. If a modern diesel has *so* much engine oil in it's
>> exhaust so as to utterly overwhelm the effect of unburnt/burnt diesel
>> oil in the exhaust
>
>that is not what I said. I was reponding to the statement you made "in a diesel, oil in
>the exhaust will be entirely made up of unburnt diesel not engine oil."

It is in effect 'entirely' as the portion of engine oil artifacts is
negligible in this case (swirl flap failure). I'm an engineer not a
pedant.

>Do you think that when a car starts up and blue smoke comes from the tailpipe, that that
>blue smoke is unburnt fuel ???

Unburnt (in varying degrees) diesel can produce all sorts of colours
of smoke. I've seen white, blue, brown, black...and variations in
between.

I might be very slow on the uptake here but I'm starting to piece
together comments which suggest, to me, that your expertise/experience
is more in petrol engines than diesel ones? Some of your comments
while very true of petrol engines are not quite so true of diesels,
IMHO.

>>then the engine is a wreck and worthless IMO. Who
>> cares at that point if it munches the swirl flaps. I've never owned a
>> diesel that burned *any* measurable amounts of engine oil. Burning
>> diesel oil produces carbon deposits..often called soot.
>
>No, the soot (or particulate matter) is unburnt fuel. Hopefully, none should get past the
>DPF.

Yawn. 'Burning' diesel in a car produces soot because it doesn't all
actually *burn* - yes, I do know that. If I were to have to (as it
would seem) explain precisely how a 4 stroke deals with it's fuel in
every sentence or use shorter more commonly used simplifying words
like 'burned' then this conversation would be a lot more tedious than
it already is.

Nevertheless, the soot in diesel exhaust *will* be available to build
up on the swirl flaps to a vastly greater degree than any engine oil
artifacts..no?

>> Mentioning the fuel wasted by A/C while owning a 335d *is* a tad
>> bizarre.
>
>We get an average MPG of 39.4, which is better than our 330d, and nearly as good as our
>320d s, and much, much better than the Ford Focus. That is not computer mpg, but
>calculated from miles driven divided by gallons used.

Why didn't you get much better mpg from the 320d - it's got much
better figures than the 335d. Was it faulty, poorly driven or badly
maintained?

>The research I have done points to different makes of fuel performing differently. I will
>not *give* away info that I have been paid to ascertain.

LOL..a 5th Gear episode (repeated in the last two weeks on Quest)
showed that..there's no need to be precious.

>>>>I've not been convinced by the cheap/expensive fuel
>>>> debate - particularly for diesel.
>>>
>>>You will if you continue to use supermarket fuel extensively.
>>
>> I don't believe so. It didn't happen in the past so, unless something
>> like the Nikasil problem is lurking in my engine, I don't expect any
>> problems now. It's certainly not something I worry about in a diesel.
>
>You should do.

Forgive me if I don't.

When/if the injectors fail (as they are likely to do in most
installations given time) I'll just replace them. Big deal. Worrying
about stuff like that carries too high a mental cost.

>The direct injection Piezo injectors in your BMW engine are more susceptible to fouling
>from poor quality fuel than the injectors of 10 years ago.

That's not unexpected..the nozzles are getting smaller and delivering
smaller amounts of fuel.

>I have written before that
>during manufacture, the Piezo injectors are flow tested by the manufacturer to enable
>them to have a "correction factor" that needs to be programmed into the ECU of the
>receiving car, for that particular cylinder, to accurately inject the precise quantities
>required per injection, up to 5 per cylinder per 4 stroke cycle.
>Thus, the cleanliness of your diesel injectors is more critical than those in most petrol
>cars.

I expect it'll become similar for petrol engines as they move more to
smaller capacity, direct injection and boosted air.

>No, the cost of living is higher, meaning people have less disposable income. There are
>also more OAPs whom cannot afford newer cars.

LOL.

>>>The different models have different variations fitted to the cars. Our (August) 2009
>>>335d
>>>only has one of these functions. That is the "Brake Energy Regeneration", nothing else.
>>
>> So how do BMW do it?
>
>Do what ?

Doh. "Brake Energy Regeneration" - as suggested in the last statement
you made prior to my question.

--
Z