Kevin J. Slater wrote:
Mine isn't very accurate. Shows low even when the level is right between
the add and full marks. Marshall says that sometimes Mobil 1 will bring
a flaky sender back around after a while. I replaced the one in the 300E
to get it back into proper order. Probably do the same with the 300TD
sooner or later.
There are AT LEAST four different errors that afflict the oil level
sender introduced in the mid '80s. The sender can short or open (those
are the simplest pair of failures and replacing the sender solves them).
Then there is the sender mechanism crudding up with engine sludge. When
this happened to MY cars, I have ALWAYS been able to cure it (within
4-8kmi) by changing from conventional oil to Mobil synthetic, but this
seems less effective in gasoline models. This has not worked for ALL
engines however and in some the sender must be cleaned or replaced.
Finally, there are the electrical failures of the delay circuit in the
dashboard. There is a delay circuit that prevents the warning light from
illuminating for a minute after the level drops below the minimum level.
This is necessary to prevent the low oil light from illuminating every
time you make a left turn, accelerate or decelerate. The factory
solution for this failure is to replace the entire instrument cluster
printed circuit assembly! No diagrams of the circuitry are available and
nobody I know has determined which parts cause the delay circuit to stop
working.
Because of the delay circuit, the low oil light can NOT be used as an
emergency indicator of catastrophic oil loss because by the time the
light illuminates, the engine would be toast. The low oil indicator was
designed ONLY as a reminder that the oil level reached the ADD mark and
can safely be topped up (Mercedes stipulates that oil should ONLY be
added when the oil reaches the ADD mark).
The only timely warning of rapid oil loss is the oil pressure gauge.
Recent Mercedes engines do not have oil pressure gauges, but MAY have
low oil pressure as well as low oil level lights. Modern Mercedes
engines also do NOT have dipsticks. Only the oil level light notifies
you that engine oil needs to be topped up and there is no way to
establish what the level of oil in the sump actually is except to buy a
$100 "service" dipstick and some non-reusable plugs to put in the
dipstick hole.
Marshall
--
Marshall Booth (who doesn't respond to unsigned questions)
"der Dieseling Doktor" [EMAIL PROTECTED]
'87 300TD 181Kmi,'87 190D 2.5 199Kmi, '84 190D 2.2 227Kmi, '85 190D 2.0
159Kmi, '87 190D 2.5 turbo 234kmi
