OM 642.930 engine worn out or bad technicians ???

[borisfilipov]

Hello. Ive bought w221 on 240k miles on the clock . First trip i had was like 2k miles . in the middle of my way back home yellow light come to add some oil . i did add 5w30 and after another 1000km lamp came back. total i added like 3Litres for 3000km. came back and serviced the car from A to z. car runs very well . when idle no smoke coming from exhaust . when driving hardly and kick down a little black/grey smoke comes out . Turbo has no moves( donno how is the word) . its basicly new ( 20k miles droven with it ) . car runs very good but where the oil came ??? nothing shows on star , no check engine ? when changing oils i have replaced 2 orange seals around the turbo charger , they were broken . the only mistake star gives is 2644 something about the MAF sensor i think . nothing else . car puls out very good . and here comes the question , spoke to 3 technicians not in official dealreship but others , all they think engine worn out . pistons /rings ... something like that . but until i open the engine and see nothing is sure . fixing this would cost me around 2k gbp and am not going to do it . before i sell the car for spares repairs i eant to be sure im not making mistake . please help me . what are the symptoms if pistons are worn out ? also i have a little oil in the left air filter box . engine is so quiet and running so good that i cant belive it can be worn . turbo is good , what else left ?


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[Botus]

a decent service and a clean of the oil breather system would help.
as it has a big engine cover, it will hold quite a lot of oil from any external leak without dropping on the road

do the service, check for leaks, fill completely 8.5ltr ??? and drive normally and see where you are....

in the old days (40 years back) 200 miles a ltr was fairly common on some engines....
these days 1000 miles a ltr is considered higher than you want... (but plenty of old engines with be around this area !!!)
5000 miles a ltr is perfectly acceptable


cars engine wear not on mileage, but on abuse and or bad quality at build when new... cheap quality fuels, thrash from cold, short journeys, use naff oil and change late, expect 60k miles,

luck of the draw well made engine, run in by an expert, never enable the stupid stop start wear my engine out system, use expensive oil and fuels, change a bit earlier than schedule says, and fully warm up before more than 2.5k revs or 1/3 throttle is used, and no journey under 10 miles each time, and it will do 600k miles

 

[Westheath]

Have a compression test done.

 

[borisfilipov]

will a compression test show if pistons weared out or broken ring or whatever ? i was thinking about that . any other thing that i can do ? i go at local garages because dealrship give very big prices and i doubt that they understand very good . everybody in my country trying to take ur money but not to fix the problem . and all i have left is asking in forums . what else except for compresion trst can be done ?


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[borisfilipov]

car is now serviced , new engine oil , new transmission oil . everything . new filters . but like i said after the change left filter box has some oil . turbo seal orange color changed with new .


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[borisfilipov]

car is now serviced , new engine oil , new transmission oil . everything . new filters . but like i said after the change left filter box has some oil . turbo seal orange color changed with new .


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[LostKiwi]

There are 2 types of rings in an engine:
Compression rings and oil control rings.
A compression test will show if compression rings are worn but won't show if oil control rings are worn.

I wouldn't fret overly about oil in the filter housing as it's likely just the breather.

 

[borisfilipov]

There are 2 types of rings in an engine:
Compression rings and oil control rings.
A compression test will show if compression rings are worn but won't show if oil control rings are worn.

I wouldn't fret overly about oil in the filter housing as it's likely just the breather.

so mister , what if on compression test all is good ? and do u suggest star diagnose compression test or need to remove the glow plugs and measure manually ? if all good , them what should i do ?


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[borisfilipov]

what ive been told is that the beds of the pistons can be ... how to say, bigger then needed and oil goes there . i was told head given to technician for some fix , 6 new pistons , and gaskets bla bla bla ... 2k. and engine was going to be ok for the next 200-300k miles . i decline to belive this because engine sound wonderfull, quiet , smooth .


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[turbopete]

these days 1000 miles a ltr is considered higher than you want... (but plenty of old engines with be around this area !!!)

just as a matter of interest, a lad at work has a $hitroen DS3 1.6VTi (petrol) which gets through a litre of oil every 1k miles, 62 plate with about 30k miles currently (it had about 22k when he got the car, his first car after passing his driving test) and $hitroen say that's NORMAL (and acceptable) oil consumption for that engine!!!!

now when I think back to 80s Fords, back when a diesel engine was expected to use oil (a little) we were lucky to put a litre in between services (6k miles) in ANY of ours, and we never put ANY oil between services in our old Cortinas etc. the garage I worked in had customers with old Ford 1.6 diesels (or the Peugeot engine 2.3 sierra diesels) who didn't even know where the bonnet release was on their car! yet we never had one that seemed low on oil (you got a rough idea how much should come out of the sump into the bucket when you drained the engine to change the oil) so it does seem that modern engines, either through the use of thinner oils (for emissions etc) or through having worse tolerances now, use MORE oil than older engines

 

[LostKiwi]

so mister , what if on compression test all is good ? and do u suggest star diagnose compression test or need to remove the glow plugs and measure manually ? if all good , them what should i do ?


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If it' all good it would suggest there's nothing wrong with piston and bores but that said you may still have worn oil control rings although if they were worn I'd expect low compression from worn compression rings.

 

[borisfilipov]

If it' all good it would suggest there's nothing wrong with piston and bores but that said you may still have worn oil control rings although if they were worn I'd expect low compression from worn compression rings.

am not sure if i understand well . ill measure compression , what it should be ? u did not told me manually to measure or with star disgnose it has this option . and what compression should be ? i was reading about 18:1 something like that . anyway if compression on all cylinders is good , then what i have left ? what is oil control rings and do i need engine open to change them ?


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[EmilysDad]

just as a matter of interest, a lad at work has a $hitroen DS3 1.6VTi (petrol) which gets through a litre of oil every 1k miles, 62 plate with about 30k miles currently (it had about 22k when he got the car, his first car after passing his driving test) and $hitroen say that's NORMAL (and acceptable) oil consumption for that engine!!!!
.....

That's the same engine as EmilysMum's C3. For all its many faults, oil consumption isn't one of them ...... just about to clock 32000 miles on a 60 plate.

 

[LostKiwi]

Compression rings sit at the top of the piston and oil rings sit below them just above the con rod pin. Worn compression rings will result in low compression and would suggest the oil consumption is due to worn rings and bores.
Good compression suggests the bores and rings are ok however it is possible for compression rings to be ok and oil rings to be worn (but rare) so good compression is not definitive.

 

[borisfilipov]

Compression rings sit at the top of the piston and oil rings sit below them just above the con rod pin. Worn compression rings will result in low compression and would suggest the oil consumption is due to worn rings and bores.
Good compression suggests the bores and rings are ok however it is possible for compression rings to be ok and oil rings to be worn (but rare) so good compression is not definitive.

can you write me 1 -2 -3 what should i do before open the engine ? like measure compression , check turbo , look PCV ( dont know what it is but ive came across people telling its possible ) ... and so on


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[LostKiwi]

That' your 123 right there.

 

[borisfilipov]

That' your 123 right there.

what is PCV can u show photo . turbo is basicly like new . 20 000 miles droven ( 2 years old ) not big move .


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[LostKiwi]

Sorry I don't have your engine so can't get a photo (mine are all petrol).

 

[Botus]

just as a matter of interest, a lad at work has a $hitroen DS3 1.6VTi (petrol) which gets through a litre of oil every 1k miles, 62 plate with about 30k miles currently (it had about 22k when he got the car, his first car after passing his driving test) and $hitroen say that's NORMAL (and acceptable) oil consumption for that engine!!!!

now when I think back to 80s Fords, back when a diesel engine was expected to use oil (a little) we were lucky to put a litre in between services (6k miles) in ANY of ours, and we never put ANY oil between services in our old Cortinas etc. the garage I worked in had customers with old Ford 1.6 diesels (or the Peugeot engine 2.3 sierra diesels) who didn't even know where the bonnet release was on their car! yet we never had one that seemed low on oil (you got a rough idea how much should come out of the sump into the bucket when you drained the engine to change the oil) so it does seem that modern engines, either through the use of thinner oils (for emissions etc) or through having worse tolerances now, use MORE oil than older engines

when I was working on cars at the Rover end of our garage... it was VERY common to drain next to nothing out at a service on some cars. With 12k intervals and 1 ltr of oil every 3 k being very low oil consumption. That means with most owners never opening the bonnet or checking the oil, there was nothing there.

meanwhile - at our end, as for high consumption, (I edited my original post....) I believe Jag factory once said 100 miles a pint was acceptable on a new car !!!

what's normal on the plastic piston VAG cars between 2005 and 2009? these used oil like it came out the ground....

 

[Botus]

what is PCV can u show photo .

PCV = positive crank case ventilation....

law says an engine can't vent crank cases gases to atmosphere... basically must go back in the engine via the air intake system
a PCV valve helps manage this system...

there is a modified engine breather for your car - that's a part you played with on some of the orange seals to the left of the turbo... its has a mesh oil separator to stop the oil mist going in the intake system. This might be completely blocked and cause part of the issue you have (hence my first post saying to clean it) and not sure how or why - but on this engine it also connects part of the electrical / engine management system - that must do something to manage the flow of crank waste gases.

get this system wrong and it will cause high oil consumption... because there is massive air flow beneath the pistons and nowhere to go so it forces oil up past the piston rings in the wrong direction

each time the top half of the engine takes in 3 litres of air (on each revolution) you displace just as much beneath them... this mixes with the oil thrown around and you have to mange it !!!! pumping losses on a 750cc high revving bike engine (moving air about below the pistons) at 10,000 rpm involves 100bhp just to get to those revs... to get any to do something useful it has to make a lot more on top of that first wasted 100bhp.... piston engines work hard and move shed loads of air

old oil also causes the breather system to struggle (don't know why but they do), if you do an oil change and then test the exhaust gas emissions it goes down... many a car would pass MOT after an oil change, when was a failure before

from the way you wrote your first post I still don't know what your real oil consumption is....