Engine failure, what will I find?

[addyguy]

I wouldn't have bothered with an engine replacement o a 13-year old vehicle, Mercedes or not.

Once you add up the cost of the engine replacement, and other stuff that is bound to go wrong on a car that old, you could have bought a newer, more reliable car.

But hey, you live in London - money is obviously not an issue!

 

[The_Eric]

Originally Posted By: The_Eric
Those cylinders look pretty good of cross hatch. I wonder if the motor was dusted? I replaced a while back that suffered that fate and the bores looked similar. Also had tons of oil in the intake tract too.



Oh wow... smart phone auto-correct failure!

That post should have rear: Those cylinders look pretty void of cross hatch. I wonder if the motor was dusted? I replaced a Pentastar 3.6 a while back that suffered the same fate and the bores looked similar. Also had tons of oil in the intake tract too.

 

[kc8adu]

i see same smoking from all pipes.unless it has a common muffler that leads to all the tailpipes that thing is blowing oil on all 8.
iirc the nikasil linings dont get honed so that is why no crosshatch.
methinks there is a simpler cause that would not require a teardown.
the rapid onset of the issue is another clue.

 

[kc8adu]

no edit and forgot what i was thinking.
this almost had to be some pcv/crankcase vent system issue.

 

[Ohle_Manezzini]

Valve seals. Look where the oil hits the piston crown in the worst seeper. #1 is clean of carbon right below where the open intake valve area...

Also, this engine looks to be running cold. That's a carbon up cc.

 

[turtlevette]

Originally Posted By: alexanderfitu
Hi all


Lots of oil on the inlet valve on no 1 cylinder:





That's the problem. That oil looks like it was poured right out of the bottle into those intake ports.

How can you not think that's the problem?

 

[alexanderfitu]

To address the multiple responses (I get no email notifications, even though they are enabled?)

Its always had a 229.5 diet.

The PCV system is clear and has been tested on both banks prior to removing the heads. I don't take an engine swap lightly!

The head gasket had no obvious signs of failure between channels, but did the engine did have evidence that the heads had been removed before. I have owned the car for 3 years and it has full history. The amount of silicone sealer used, especially around the head gaskets, is not OEM.

To the people who are convinced of a valve stem failure issue. How do all valve stem seals fail exactly at the same time? There is obviously an issue with one side of the block only.

 

[alexanderfitu]

Originally Posted By: turtlevette
Originally Posted By: alexanderfitu
Hi all


Lots of oil on the inlet valve on no 1 cylinder:





That's the problem. That oil looks like it was poured right out of the bottle into those intake ports.

How can you not think that's the problem?


Because valve stems don't all fail at the same time, and this engine has huge plenum chambers above the valve stems where oil can hang out in low velocity air?

 

[Ohle_Manezzini]

If the pcv is fine, the valve seal are good, the compression are decent, what remains? Overfilled sump to cranckcase? Pcv can't manage a serious ovefill.

 

[Merkava_4]

Being that the engine is supercharged, it was probably run on low octane fuel and one time and the pre-detonation broke the piston rings. Instant oil consumption.

 

[alexanderfitu]

Originally Posted By: Merkava_4
Being that the engine is supercharged, it was probably run on low octane fuel and one time and the pre-detonation broke the piston rings. Instant oil consumption.


I think this is the most likely culprit. The engine does have 2 knock sensors it uses but they have obviously not caught this one out. Piston no 1 has slightly more plat in the bore than the other 3. I think this has a broken ring land or broken rings somewhere.

 

[alexanderfitu]

Originally Posted By: Ohle_Manezzini
If the pcv is fine, the valve seal are good, the compression are decent, what remains? Overfilled sump to cranckcase? Pcv can't manage a serious ovefill.


I think broken rings/ring lands.

 

[Ohle_Manezzini]

Originally Posted By: turtlevette
Originally Posted By: alexanderfitu
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That's the problem. That oil looks like it was poured right out of the bottle into those intake ports.

How can you not think that's the problem?

This^.
A broken ring wouldn't spit oil over intake valve tulips, like that ...
I get that as a purgant valve cleaning job (google purante at utube). You jet oil on intake pipes to do it, like seafoam...
Is this a troll?

 

[PeterPolyol]

I'd say there is quite a bit of blowby/crankcase pressure due to piston ring damage and that the excessive pressure is pumping oil into the intake tract. Being a supercharged engine, the pressures would be higher than normal and the issue more pronounced. Did you do a quick observation of the state of blowby before the teardown? Indeed it could be a compression ring or ringland, possibly but not necessarily the oil control rings as that oil appears to be from the intake tract

 

[funflyer]

Originally Posted By: The_Eric
Originally Posted By: The_Eric
Those cylinders look pretty good of cross hatch. I wonder if the motor was dusted? I replaced a while back that suffered that fate and the bores looked similar. Also had tons of oil in the intake tract too.



Oh wow... smart phone auto-correct failure!

That post should have rear: Those cylinders look pretty void of cross hatch. I wonder if the motor was dusted? I replaced a Pentastar 3.6 a while back that suffered the same fate and the bores looked similar. Also had tons of oil in the intake tract too.


Aluminum block with alusil cylinder liners will have no cross hatch. These get a final lap or polish with felt and will show no machine marks. What I see are scored cylinder walls. Combine this with low tension rings and a supercharger and you have excessive crankcase pressure and a serious oil consumption problem thru the PCV system. You won't find any broken rings either. At 99K it's toast. It ain't a SBC...

 

[The_Eric]

Interesting. I was thinking that the bores were Nikasil, which would normally have crosshatching.

At any rate, I'm thinking along the same lines as you- excess crankcase pressure leading to oil being pushed into the intake tract.

 

[alexanderfitu]

EDIT: Whoops, did not realise I had already posted these!

Sump removed and was full of Aluminium.... All 8 cylinders showed issues with scoring. Still think detonation caused broken rings/ring lands.

 

[Vikas]

Oh man; Are these engines known to have such a short life?

 

[RoadRaceJosh]

Can you describe the aluminum or post photo?

 

[Doog]

Originally Posted By: alexanderfitu
EDIT: Whoops, did not realise I had already posted these!

Sump removed and was full of Aluminium.... All 8 cylinders showed issues with scoring. Still think detonation caused broken rings/ring lands.


its abgestorben..........