Yes, and if the tops are not kept cool, oil can burn on the rings and
in the grooves. This will create a problem similar to what Peter
described. As always, it is just something to check, and not a diagnosis
At 05:37 PM 10/27/2008, you wrote:
The oil spray nozzles are used for cooling the piston tops.
Thanks,
Tom Hargrave
www.kegkits.com
256-656-1924
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of Loren Faeth
Sent: Monday, October 27, 2008 5:05 PM
To: Mercedes Discussion List
Subject: Re: [MBZ] Oil analysis problem
Is it possible the piston oil spray nozzles were not cleaned and
working during the previous rebuild? That might account for the
rings being carboned up the first time, and again now.
At 04:40 PM 10/27/2008, you wrote:
>Hi Peter --
>You asked <<what actually lubricates the bores? is it splash/leaks
>from the small end?>>
>
>IIRC you wrote that a 300 W123 was the problem (in your fleet ;-)
>and I believe - not 100% sure - the 300D Turbo had squirters under
>the pistons and the non turbo did not - I believe those squirters
>cool the piston crowns and provide some lubrication to the cylinders
>- otherwise it comes from splashing of the crank.
>
>The carbon on the rings certainly sound like a strong
>likelyhood. What kind of driving does this car see? Any long
>distance/high speed stuff?
>
>I do not believe it has anything to do with your rebuilding
>technique. I suspect you are right about the machine shop not
>having enough crosshatch to get good ring bedding.
>
>It's also extremely important to have a shop that is xperienced with
>MB - hopeflly yours was. When I rebuilt my 240D I replaced the
>sleeves and pistons/rings - I had to replace the pistons because
>several rings had broken and damaged the piston grooves/lands.
>
>But when honing for new rings it's not all that difficult to do -
>
>Let me ponder this some -but those carboned rings really sound like
>the problem - but I wonder what caused it the 1st time? Any idea?
>
>Later --
>
>Sincerely,
>Larry T (74 911, 91 300D 2.5T)
>www.youroil.net Oil Analysis Kits &
>Porsche Posters/Weber parts
>----- Original Message ----- From: "Peter Merle" <[EMAIL PROTECTED]>
>To: "Mercedes Discussion List" <mercedes@okiebenz.com>
>Sent: Monday, October 27, 2008 1:57 PM
>Subject: Re: [MBZ] Oil analysis problem
>
>
>>Larry , compression is down - around 18 bar all round and starting has
>>become more slightly more difficult. It did not achieve full 24 bar when
>>newly overhauled and I can only ascribe this to not optimal machining.
>>honing by engineering shop - perhaps this is the cause of the malay?? Oil
>>pressure is 2 bar at idle hot and it pegs at 3 immediately. Was thinking
-
>>what actually lubricates the bores? is it splash/leaks from the small end?
>>What is also unusual is that when I overhauled the engine all the rings
>>where carboned up onto the piston on all 5 pistons. I suspect the same
might
>>be happening again. I was not however my driveing that contributed to this
>>as I had just bought the car when I overahuauled it. My other Om617's show
>>now sighn of similar problems - I also overhauled my 300GD ( a crack in
head
>>that had been repaired by previous owner was starting to leak ) and thats
>>going well. Oil consumption is still low ( arround 0.2 l/ 1000 km )
>>PEter
>>
>>
>>
>>2008/10/27 LarryT <[EMAIL PROTECTED]>
>>
>>>is the oil consumption from leaks or is it being burned?
>>>
>>>If burning, the time it is burning will help understand what might be
>>>wrong. If after idling for a few minutes you accelerate and leave a smoke
>>>trail bad valve guides are indicated. If it has white oil smoke
>>>whiledriving at a steady speed, rings are likely the problem - or
something
>>>related to the pistons.
>>>
>>>A single oil sample is not as informative as several - preferably at
>>>intervals of 1500 miles or more.
>>>
>>>As Curt pointed out, results are best evaluated over time. The history
of
>>>the engine is helpful info also - if used for short trips where it was
not
>>>warmed enough to burn off carbon deposits a misleading indication can
ccur
>>> --
>>>
>>>Sincerely,
>>>Larry T (74 911, 91 300D 2.5T)
>>>www.youroil.net Oil Analysis Kits &
>>>Porsche Posters/Weber parts
>>>----- Original Message ----- From: "Peter Merle" <[EMAIL PROTECTED]>
>>>To: "Mercedes Discussion List" <mercedes@okiebenz.com>
>>>Sent: Sunday, October 26, 2008 4:04 AM
>>>Subject: [MBZ] Oil analysis problem
>>>
>>>
>>> Sent oil samples from my 5 300D 's to the lab ( 3 x W123's , 1x 300GD (
>>>>OM617 ) and 1xW124 ) and got satisfatcory results from 3 off them . The
>>>>one
>>>>W123 ( the only one running Mobil 1 ) had high levels of Copper and Iron
(
>>>>29 and 71 ppm ) after 2000 km. Sodium, Siicon, Al , Cr , particulates,
>>>>soot
>>>>are all low . Lab suggested the oil pump is worn and I should test oil
>>>>pressure . Well the oil pump had done only 60000 km and oil pressures
are
>>>>good. The engine is loosing compression and oil consumption has
increaseed
>>>>since engine rebuild a few years ago so something is not right. Any
>>>>ideas
>>>>anyone?
>>>>
>>>>Am going to change oil to delo 400 and then see what the results are.
>>>>
>>>>Regarding the other car with poor results - I had just bought it - has
>>>>been
>>>>running on WVO for 30000 km - well its oil had high levels of iron ( 93
>>>>ppm
>>>>) as well as particlates - diagonis by lab was that oil filter was being
>>>>bypassed ie filter blocked. is this a problem with WVO ? Does the stuff
>>>>get
>>>>into the engine oil and block the filter?
>>>>
>>>>Peter
>>>>_______________________________________
>>>>http://www.okiebenz.com
>>>>For new parts see official list sponsor: http://www.buymbparts.com/
>>>>For used parts email [EMAIL PROTECTED]
>>>>
>>>>To Unsubscribe or change delivery options go to:
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>>>
>>>
>>>_______________________________________
>>>http://www.okiebenz.com
>>>For new parts see official list sponsor: http://www.buymbparts.com/
>>>For used parts email [EMAIL PROTECTED]
>>>
>>>To Unsubscribe or change delivery options go to:
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>>_______________________________________
>>http://www.okiebenz.com
>>For new parts see official list sponsor: http://www.buymbparts.com/
>>For used parts email [EMAIL PROTECTED]
>>
>>To Unsubscribe or change delivery options go to:
>>http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
>
>
>_______________________________________
>http://www.okiebenz.com
>For new parts see official list sponsor: http://www.buymbparts.com/
>For used parts email [EMAIL PROTECTED]
>
>To Unsubscribe or change delivery options go to:
>http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Loren Faeth
_______________________________________
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_______________________________________
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Loren Faeth
_______________________________________
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