Some of the standard tests might help - leakdown test, compression test,etc
might offer a clue.
If those tests show a low cylinder *then* a teardown is last resort - IMHO.
Hard starting when cold (the colder the better) will be the best test of the
cylinder head / combustion system than anything else. A engine rebuilt that
recently should behave like a new engine fresh from the MB dealer.
Low oil pressure indicates a main bearing problem - when the engine is fully
warmed up - and the oil is warmed also - the oil pressure should jump to
the peg and be at 3 bar/45# or so before you are at 3000rpm- that's
according to the manual - and probably covers high mileage engines also. On
a rebuilt engine I'd expect to see it idle just below 2 bar (a little less
than 30) when warm and go to 3 bar (45) as soon as the accel pedal is
pushed.
Rod bearings are tough to diagnose on a diesel - because of the noise alwys
present -
But the above might be a start -
Sincerely,
Larry T (74 911, 91 300D 2.5T)
www.youroil.net Oil Analysis Kits &
Porsche Posters/Weber parts
----- Original Message -----
From: "Curt Raymond" <[EMAIL PROTECTED]>
To: "Mercedes Discussion List" <mercedes@okiebenz.com>; "Peter Merle"
<[EMAIL PROTECTED]>
Sent: Sunday, October 26, 2008 1:27 PM
Subject: Re: [MBZ] Oil analysis problem
Interesting, the rebuild was 60,000 km ago? Thats not long at all, clearly
something is wrong and unfortunately I'd have to guess that a teardown is
the only way you're going to know...
-Curt
--- On Sun, 10/26/08, Peter Merle <[EMAIL PROTECTED]> wrote:
From: Peter Merle <[EMAIL PROTECTED]>
Subject: Re: [MBZ] Oil analysis problem
To: [EMAIL PROTECTED], "Mercedes Discussion List" <mercedes@okiebenz.com>
Date: Sunday, October 26, 2008, 1:06 PM
Yes indeed I rebuilt the engine myself 5 years ago. I was meticulous and
used OEM parts throughout. Used dino oil for the first two changes 500, 5000
km then switched to Mobil 1 . It never ran low in oil. Running in was
carefully done follwing recommended practice.
Peter
2008/10/26 Curt Raymond <[EMAIL PROTECTED]>
The one with high iron levels, did you do the rebuild yourself? Sounds like
a bad job was done and the rings are breaking down...
When I first got my 190D oil analysis showed high iron levels and would
force an oil change at ~8000 miles. Over the next 20,000 miles or so the
iron levels reduced at each change so that now after ~75,000 miles of
ownership iron levels are normal at 15,000 mile oil changes and I'm
pondering 20,000... During the time of high iron levels the car started fine
and had normal power. I theorized the car was carboned up and had sludge
from the previous owner using cheap oil...
-Curt
Date: Sun, 26 Oct 2008 10:04:15 +0200
From: "Peter Merle" <[EMAIL PROTECTED]>
Subject: [MBZ] Oil analysis problem
To: "Mercedes Discussion List" <mercedes@okiebenz.com>
Message-ID:
<[EMAIL PROTECTED]>
Content-Type: text/plain; charset=ISO-8859-1
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
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