munched engine...ouch! not for the faint of heart

[BlingBling]

FYI: Scoring of the piston bores is a know problem, albeit in a few cases, on the B6/B7 S4's and they are not effected by carbon build up. IIRC this has been attributed to over fuelling resulting in diluted oil and/or contaminants.

[2manytoys]

B6/B7 S4's are not direct injection, they wouldn't suffer from carbon on the valves anyway. I agree over fuelling could do this. I logged AFR too, and this was ok when under load. Maybe a leaky injector could make idle too rich, but it never ran rough.

Cheers.

[Doug_S2]

I am sure if you look at what comes out of just 5 ports (because only 5 are shut) with a hoover (that is a standard size henry that was emtpy and cleaned before removing the loose deposits) the deposits going in under normal driving cannot be good for bores. You cannot break some of the hardened parts in that with your finger nails.

I am sure you can screw the bores if you are not careful but since March 2009 we have cleaned 41 different cars with no catastrophic failures.

[ArthurPE]

I am sure if you look at what comes out of just 5 ports (because only 5 are shut) with a hoover (that is a standard size henry that was emtpy and cleaned before removing the loose deposits) the deposits going in under normal driving cannot be good for bores. You cannot break some of the hardened parts in that with your finger nails.

I am sure you can screw the bores if you are not careful but since March 2009 we have cleaned 41 different cars with no catastrophic failures.

yep, that's the correct way...MUST have a vacuum...
valves under 'the knife' must be shut
you must be doing it right

if you look at the scoring it does look like it's drawn down, not up, so kind of makes me think it is not deposits...and is under the piston, not on top...

under normal driving the stuff that enters the cylinder, imo, is oil, and relatively harmless, the oil that hits the valves, stays there, coked on, with little chance of dislodging it self....it's very difficult to get the crud off...if it did come off I'm guessing it would burn or be blown out, but not score the cylinders like that....

I'd pay to see the oil filter, lol

ps: next time dry it in a uwave and weigh that shyte, I'd like to know wt/valve per k miles...

[2manytoys]

I'm not sure it's come from the bottom (oil) but not sure yet (I may never know for sure, it may be Audi's secret)

This picture shows scoring right at the top. Wouldn't it suggest damage from the top (as the rings wouldn't get up that high?)



Agree on removing the carbon from the cylinder, I'm sure any real mechanic that sees this would be shocked, and make sure they remove it all from the bores given how hard it is (it's like little rocks).

[stoddie]

im not sure what the clearance would be from the piston crown to the bore of the cylinder - im sure someone can shed some light on it, but i would still think it will be a fraction of a mm. the bump clearance ( distance from the top of the piston to the head) will also be minimal for high compression. again im not sure what that figure will be.

I stand by my theory that its came from the top when its been cleaned. and the carbon has slowly scraped away the oil film and the cylinder bore.

[2manytoys]

I stand by my theory that its came from the top when its been cleaned. and the carbon has slowly scraped away the oil film and the cylinder bore.

I don't think so, as a massive amount of carbon was already there (not many kms too). Here is a picture of what it looked like the very first time the manifold come off (keep in mind it was that bad that the car was pinging and timing was only 9-13 degrees)

[ArthurPE]

any updates on the KABOOM!!!!
hopefully I'll hear some more from Audi

I had a large pump go 'tits up' today, so I'll be figuring out how to keep the shyte (literally) flowing
thing is 40 years old and we are looking at building a new pump station (40' deep, 30 x 40 area) but I plan on bidding it next month and a year to construct (1.5 mil is my estimate)
but until then, field expedient measures are required
I set-up 6 months ago for bypass pumping and the pump should be delivered by noon

[ArthurPE]

im not sure what the clearance would be from the piston crown to the bore of the cylinder - im sure someone can shed some light on it, but i would still think it will be a fraction of a mm. the bump clearance ( distance from the top of the piston to the head) will also be minimal for high compression. again im not sure what that figure will be.

I stand by my theory that its came from the top when its been cleaned. and the carbon has slowly scraped away the oil film and the cylinder bore.

who knows...but hopefully we'll find out...

the scoring looks top to bottom...

but what ever caused the scoring, the scoring caused increased deposits and the piston coking...

it could have been the cleaning
solvent saturated particles damaging the walls and coating...
do these cylinders have a treatment? they must, it's aluminum
so the abrasive deposit with solvent could possibly score them...hmmmmm

[P_G]

any updates on the KABOOM!!!!
hopefully I'll hear some more from Audi

I had a large pump go 'tits up' today, so I'll be figuring out how to keep the shyte (literally) flowing
thing is 40 years old and we are looking at building a new pump station (40' deep, 30 x 40 area) but I plan on bidding it next month and a year to construct (1.5 mil is my estimate)
but until then, field expedient measures are required
I set-up 6 months ago for bypass pumping and the pump should be delivered by noon

[ArthurPE]

just a side story to 'bump' the post
I have 'shyte' on my mind, lol
I got the call at 6 AM and an 'processing' the data
and blathering it out helps, and at least reduces stress

top vs bottom...
the rings will go almost flush with the head gasket...
and some oil (sprayed from below) will get trapped in the rings, and runn up and down...

any updates on the KABOOM!!!!
hopefully I'll hear some more from Audi

I had a large pump go 'tits up' today, so I'll be figuring out how to keep the shyte (literally) flowing
thing is 40 years old and we are looking at building a new pump station (40' deep, 30 x 40 area) but I plan on bidding it next month and a year to construct (1.5 mil is my estimate)
but until then, field expedient measures are required
I set-up 6 months ago for bypass pumping and the pump should be delivered by noon

[ArthurPE]

btw: it appears we are all jerkin' it at work?

[PetrolDave]

btw: it appears we are all jerkin' it at work?

It's Friday afternoon, I finish early

[ArthurPE]

btw: it appears we are all jerkin' it at work?

It's Friday afternoon, I finish early

enjoy

once I sort the shyte pump issue out I'll be blowing out too...
F1 weekend to boot

[silverRS4]

Ok, I changed my mind. The carbon must contribute to some of the scratching that can be seen. Although, it looks like that is not all that's going on. This seems to be the consensus, right? I can only think with pictures, so I made up a few. Mal, getting to the possible origination of fuel washing the cylinders, that can only really happen when the engine is off and a faulty injector bleeds residual fuel pressure into the cylinder. Then, upon engine start, the excess fuel causes an over-rich condition and several misfires until the excess fuel is depleted. Then the engine runs fine. Over-fueling in an RS4 while the engine is running with no CEL (MIL) would be very unlikely. As you stated with your car, the fueling is spot on while the engine is under load (as well as transitioning from a light to a heavy load). So it would be safe to say that the AFR targets are met in all conditions. The injector condition can be evaluated with a fuel system leak-down test. Was that ever done?