If there are i would like to ask:

-Is there anything special about the mercedes iron blocks ie the cast material?,the way the cylinders are honed?,the angle of the cross hatch?...the depth of the hone cut....is it any different from your average engine??.

The reason i ask this is im alittle frustrated with how much time and effort has gone into my engine and i still dont have it how i want it...that is,with just black smoke emitting from the exhaust.

I pulled the turbo off this weekend to check the seals and its fine.the valve seals are fine,there are no engine/oil vents plumbed into the intake anywhere.

The car runs oversized OE pistons and rings...professionally bored and honed by the best gear and people the market here has to offer.

The one pitfall could be that i did assemble it myself =),however it was all done by the book,assembly was spotless and had a decent running in before being driven hard...care was taken to make sure i wouldnt need to pull it apart again...
the smoke is mostly black with a slight blue tint,nothing like the blue i had on the first build when the JE pistons and rings didnt bed in.

I guess i will do a leakdown test next in the hope one of the cylinders is low and a ring is the only issue. something tells me that would be the case though.
the tune is good.


Paul

Black smoke is likely fuel related. Running way too rich. The worst of it is that you may be washing your cylinder walls with all that excess fuel which is never a good thing, but especially bad with freshly honed cylinders and new rings. You don't say what kind of car or engine so it is hard to give more suggestions.

__________________
1987 W201 190D

Did you install the rings properly?
The top and middle compression rings are not interchangeable in function.
Was the piston ring end gap within spec?

__________________
http://i19.photobucket.com/albums/b1...c/GOWIDE-1.jpg
1971 280SL ROADSTER
1988 300CE TWIN TURBO WIDEBODY
1994 E320 CABRIOLET
1999 C43 AMG
2005 G55K AMG
2008 CLK63 AMG BLACK SERIES

Hi guys,

The engine is a M111 2.3, rings were definitly installed properly in terms of #1 and #2,the tune is good and only blows a small puff of black when you nail it.there is no black smoke under normal driving.

The ring gap may be a spot to consider(i was told it wouldnt be)
The guys who honed the block gave a slight increase in piston to bore clerance to counter the higher heat we were to see at 15psi. the factory clearance was something like .8 thou and they increase it by a very very small amount,I did query this and apparenty would have had next to no difference in the factory set ring gap which was checked by them after the hone.
However as i didnt actually see or measure the gap myself im not sure what it was or what it should have been,it was there job to do that.

I don't understand... in your first post you are "frustrated with how much time and effort has gone into my engine and i still dont have it how i want it...that is,with just black smoke emitting from the exhaust."

It sounded like you had so much smoke that you were compelled to feel there was a serious problem with the rings, bores, turbo, etc.

In your last post, you say it "only blows a small puff of black when you nail it.there is no black smoke under normal driving."

I'd say that a "small puff of black when you nail it" is entirely normal and appropriate for an engine that has been set up for high performance.

I think I still may be misunderstanding the problem.

__________________
1987 W201 190D

Sorry for the confusion,i ment that it doesnt blow any smoke under normal driving no blue or black...so there was no overly rich situation on run-in.

It does blow black under WOT which is normal....however it has a blue tint to it which indicates some oil burning.

Valve seals.

__________________
1987 SDL. The best there ever was.

It is confusing !!!

Do a leak down and compression test.
This will rule out rings and if they are damaged or not seated.

Look at your plugs while they are out.

The black smoke now that you've explained a bit more appears as Jon L posted to be fuel related.

The "blue tint" is subjective...
"Black under WOT " is not normal.

What type of turbo and what is your boost set at.
How are you enriching.
Possible you have blow by under boost pressure which may be getting into the intake ?
How are you venting the crankcase?

__________________
http://i19.photobucket.com/albums/b1...c/GOWIDE-1.jpg
1971 280SL ROADSTER
1988 300CE TWIN TURBO WIDEBODY
1994 E320 CABRIOLET
1999 C43 AMG
2005 G55K AMG
2008 CLK63 AMG BLACK SERIES

how long ago was the rebuild?

Have you set the rings yet with a high load run?

Do some searching on common practice for break-in procedures; they usually require 60% - 75% of max power over a certain time span.

Upside down rings?

__________________

http://www.mototuneusa.com/break_in_secrets.htm

this kinda outlines what I am getting at.

But also search the aviation industry for more compelling and scientific studies of this theory.

__________________

Well i say, from what i have seen in Mitsubishi evo rebuilds, is that the piston to wall clearance is not much of an issue on how much oil you will burn, its almost certainly going to be how the rings are gapped.

__________________
Jay,
-----------------
-1995 Blue W202 C36 AMG (M) SOLD ;(
-1995 Black W140 S500 (Lady)
-1992 Black W124 E300 (Dima) (Ex-Mosselman
Twin turbo Kit).
-1988 Black W124 300 E 4-Matic.(Nadeen)
-1983 Brown W126 500SEL.(Old Lady)(Sold)
-1981 Gold W123 280CE.(Dareen)(Sold)
http://www.youtube.com/user/jayrasheed

Nope they were replaced for a second time on the second rebuild just incase they were a problem.

Ok will do a leak down test next.
Have checked plugs,they look good.
The tune is good and the dyno runs do not show over enrichment.
There is no vents plumbed into the intake,so no way oil can enter that way full stop unless through the turbo compressor but iv checked that,turbine side is fine too.
Engine runs a GT2860RS,boost is 14.5psi,fuel is controlled by a motec M400.

Imo oil is coming in around the rings...hence why i asked this at the start if the thread:"-Is there anything special about the mercedes iron blocks ie the cast material?,the way the cylinders are honed?,the angle of the cross hatch?...the depth of the hone cut....is it any different from your average engine??.

If the answer to this is yes,its just like all other engines,then i will need to pull it apart and find out why they didnt seal...again!.

We still do not understand why the gapless ringset on the first build with JE pistons did not bed in either...maybe the ring tension,material etc etc was incompatible im not sure...

I mentioned piston to wall clearance because the mahl MB pistons for this engine come pre gapped...so a larger piston to wall clearance makes for a larger ring gap...however the increase was said to be so small that it would not effect ring gap enough to cause concern.

However this still could be the problem as i seem to have poor luck with companies getting it right.

Engine build was completed late last year,the engine has had around 3000kms on it since then,it has had the boost up'd from 5psi to 14.5 and the cam advance mapped after the run in.

Iv done alot of research on running in.

Interesting comment on the up side down ring/s maybe i got one wrong...that would be embarrassing!.