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w123 Mercedes Diesel 240d

w123 Mercedes Diesel 240d

Meet Mimsi, Our 1978 Mercedes 240d Diesel

One day I was browsing facebook marketplace and this old blue car caught my attention.  It wasn't too far away from home, the car was unique, so I clicked on it and asked the seller a few questions.  I didn't need a car, let alone a 40 year old car, but that didn't stop me from contacting him.

The conversation turned into me going and test driving the car.  It was exactly what you would expect from a 40 year old diesel.  Loud, dented, rusty, and very very slow.  My common sense had kicked in and said, you do not need to buy something else to consume your time.  We parted ways and the thought of owning this car drifted away. 

Months had passed and I was traveling for work, my flight was sitting on the runway for far too long and I started browsing marketplace again.  This blue car popped up and for some reason I sent the guy an offer.  I didn't really expect him to entertain it, but he came back with a counter and we agreed upon a price in a matter of minutes.

I paid a small amount over facebook to have him meet me at the airport when I landed.  That evening I arrived back at home with a 40 year old diesel instead of the rental car my wife expected to see me in.  It made for an interesting dinner conversation to say the least.  That is how I acquired Mimsi.  

Unexpected Mechanic

If you read a bit about the w123 series it wont take you long to learn that these cars are tanks.  They seem to last forever, but just like anything with age, things begin to break down.  Especially rubber or plastic parts.

A mechanic is a title that does not fit me.  I'm not scared of getting my hands dirty or breaking things, I just haven't had any interest in it.  I love building things, cooking, writing software, electronics, but working on cars is not one of my interests.

Well, this car changed all of that.  I started tearing it apart and fixing things one by one.  There is a lot that can go wrong on a vehicle that is 40 years old.  The fuel gauge didn't work, the odometer was stuck at 59,000 miles, the valves needed adjusting, along with all of the basics like needing an oil change, replacing fuel filters, etc.

Quickly I found entire communities and cheap parts for all of the repairs I needed to make on my 240d.  

Mercedes Diesel Repairs

There are different versions of Mercedes diesel.  The 240d I have is part of the w123 series.  300d is another model within the w123 series.  The 240 means it is a 2.4 liter and likewise the 300 is a 3.0 liter.  d after the 240d and 300d means diesel.  

240d won't shut off

These cars have vacuum lines that serve several different functions.  Shifting the automatic transmission, locking and unlocking doors, shutting off the engine, setting the cruise control. 

Air hoses or vacuum lines are made from plastic and crack and leak over the years.  The connectors are also plastic and have the same problems over time.  After a few months my car didn't want to shut off.  At first I turned the key off and it would put a little before turning off. Eventually it got to a point where it wouldn't shut off unless I went under the hood and pressed the red metal lever to shut the engine off.

I came to the conclusion that there was a leak in the vacuum lines somewhere.  At first I tried troubleshooting without the proper tools and eventually I bought a mighty vac and that made all the difference in the world.  If you are dealing with any of the above issues get yourself a mighty vac and also a hose replacement kit.  

The following kit was enough to fix the problem I was having.  Now when I turn off the vehicle it stops abruptly like you would expect an engine to when you switch the key


I also performed the following repairs and will update details of those repairs soon.

240d Fuel gauge not working

240d Odometer repair

240d valve adjustment



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