That almost always happened on the OM621 and 615 engines if the owner
let anyone else change the oil. But there is an error in the
statement: The plastic filter was not the "prefilter" it is the mail
filter, and the replaceable cartridge is the BYPASS filter. Without
the main filter properly in place the bypass does nothing.
At 10:13 PM 4/9/2007, you wrote:
3 years ago I had the oil and filter changed on my 73 220D. Several
months later, I changed it myself. I unscrewed the oil filter
housing and to my horror the prefilter was missing. Yes, my engine
oil was not getting filtered for months on end.
Loren Faeth
