I’m looking at trading a guy a truck for an 82 240D Mercedes with an automatic transmission. The car’s generally in okay shape, but apparently the previous owner made some simple adjustment to the transmission that makes it shift really late. Supposedly this was necessary for some sort of WVO system or something, but who knows. I looked in a couple of service manuals and the diagrams for the adjustment procedures for the transmission pressure rod thing doesn’t look like anything this car has. The car otherwise drives pretty good and once the tranny gets around to shifting the shifts feel perfect-- not hard or sloppy. Anyone have any idea what they did to this thing and how to undo it?
Does it have any vacuum leaks? I have a '83 240D, the transmission is partially controlled by the vacuum system, which is controlled by some small restriction in the vacuum lines (intended to replicate the vacuum of a gasoline engine under various loads). If the transmission does not get adequate vacuum, it will shift very hard and/or late. Here is a link to a service manual that might help:
I would be careful of a car that was someone’s WVO experiment unless I had it checked out first…
That is a very useful link, but it doesn’t seem to have have any information on transmissions! I have through other searching figured out that there is a little valve mounted on the injector pump that makes a controlled vacuum leak when you increase the throttle, simulating goosing it in a gasoline engine, but I can’t figure out which one of the linkage pieces needs to be adjusted.
Follow up question: why did MB insist on making everything vacuum controlled when most of their cars came with diesel engines?!
Yeah, it’s almost always a vacuum leak that causes harsh shifts on the diesels.
Try this link. It’ll save me a LOT of typing.
That’s a good article, I need to keep that for reference too.
“Follow up question: why did MB insist on making everything vacuum controlled when most of their cars came with diesel engines?!”
Because they could? If you own one of these you will become very good at finding vacuum leaks, just part of the fun.