W123

Recently, I bought a 1979 Mercedes 240d. Enthusiasts refer to this model of Mercedes as the W123. You can learn more about the W123 on Wikipedia

My W123 has 384,000 miles on the odometer. Like many W123s, the odometer is also broken. From the service history and registration information, I figure that the car has right around 400,000 miles. It is on its second engine, which, from what I can tell, has around 140,000 miles on it. It has a four-speed manual transmission, manual windows, a power sliding roof, and air conditioning, which works. It has almost no rust. It has extensive and meticulous service records from the man who owned it for 21 years, and minimal service records since he sold it to its previous owner, in 2006 or so.

This page exists to remind me about the little annoyances that I have with the car so I can fix them. They are ordered by priority. As I fix them, I will post information on how I fixed them so that others may mend their own cars.

W123 log

July 25th, 2010

The fuse for the sunroof motor was missing. This is a convenient reason for the sunroof to not work. I replaced the fuse with one from Autozone, and the sunroof was still inoperative. I will try cleaning the switch next; while the switch is off, I can test to see if it is getting power, which will help me narrow down the cause of the failure.

July 27th, 2010

I discovered that the dome light needs to be replaced, and that the idle adjuster knob on the dashboard is very likely broken. The idle adjuster knob allows you to increase the idle speed to help the car warm up. This is useful for cars that operate in cold climates, and for cars that are behind on routine maintenance like mine; without it, you'll need to give the car a little gas for the first 10-15 seconds, or it will stall. The good news is that the cable is probably something I can pick up at a junkyard (along with said dome light).

I will take it to the mechanic today to get the engine caught up on maintenance. It will definitely get an oil change, a valve adjustment, and fuel filters, and will probably also get a diesel purge, injector service, and other fluids changed as well. Once this is out of the way, it should be fine with regular oil changes and valve adjustments; services that I can perform on my own with the right tools.

July 31st, 2010

The valve adjustment, oil change, and fuel filter change were successful in the sense that the car now starts when cold, and requires no gas to remain idling when cold. This is a marked improvement over its condition when first purchased, and will give me cause to procrastinate on fixing the idle adjuster knob, something that I should definitely do before winter.

I have slowly been working the car into my regular car use. Today, it covered 35 miles without incident (though there is an intermittent noise from the rear differential. Not sure what that would be). The climate control knobs are stiff, but work. The A/C does a good job of cooling the car.

Tomorrow I will try to clean the sunroof switch. I may also get around to topping off the transmission fluid. I'm not sure that it is low (it is a manual transmission, so there's no dipstick for me to check), but reverse is notchy, and second gear grinds occasionally. If it is like other maintenance on this car, it probably hasn't been changed for 5 years, so it is due in any case.

August 2nd, 2010

I have discovered that the hood closes for real if you apply more force to it when closing it.

August 4th, 2010

I will be done with GSoC at the end of next week. After that, I have a week or so before an actual vacation to work on the car. Hopefully I can resolve most of the list down there in that week -- it seems like a lot of stuff, but most of it is little cosmetic things that won't take too long.

I managed to remove the climate control knobs, only to discover that the little plastic cups underneath the knobs are cracked and basically ruined. I also discovered that I don't have a socket large enough to fit around the nuts on the knobs to remove them. Getting the climate control unit out will allow me to replace the bulbs in the center console and test the sunroof switch, both of which are priorities.

Also, I'm going to add door seals to my to-do list. I gather that these are pretty easy, and, since mine are pretty trashed, will make the car quieter.

August 13th, 2010

I've made no progress on the car so far, but I've put probably 250 miles on it since I've purchased it without any issues. It's a very pleasant car to drive, and the working air conditioning is quite nice in the summer.

August 17th, 2010

I finally found time to get the car up in the air today. The flex discs are fine -- the rear one will probably need to be replaced before too long, but had no obvious damage. The front one seemed pretty good. I was worried about them because they weren't explicitly mentioned in the service records anywhere that I could see, and they are wear items, but I guess they were replaced not too long ago. Maybe I'll ask the previous owners if they know anything about them.

August 18th, 2010

I ordered the door seals today, along with a new air filter. While driving to the grocery store with the window open, I smelled diesel. This may mean worn injector return lines, which are a wear item and are easily replaced. Cleaning the engine bay will help reveal leaks, but that (and a car wash) will have to wait until I get the new door seals fitted.

August 21st, 2010

I checked out the injector return lines today. They're dirty, but I can't tell from that if they're leaking. I'll keep an eye on them after I clean the engine bay.

Apparently the car doesn't have front speakers at all in the usual place, and, from what I can tell, never did -- there are these circular dash-like placeholders where speakers should be, but no speakers.

I cleaned the sunroof switch, but the sunroof still doesn't work.

August 27th, 2010

The door seals have been replaced. I used non-Mercedes seals, which fit passably on 3 of the doors. I'm going to want to replace the one on the driver's side rear door soon, and I figure I'll give the others a chance to see if they work without issue. I also washed, clayed, and waxed the car. It cleans up pretty nicely for a 30 year old car.

August 30th, 2010

I drained, flushed, and refilled the coolant system yesterday. While doing that, I also replaced the thermostat and radiator cap. The car now warms up a lot faster (reaching normal operating temperature in a reasonable amount of time), but runs a little hot. Probably I have a bubble in the system that needs to work its way out.

I'm taking the car on a 400 mile road trip tomorrow. Hopefully it will be trouble-free.

The to-do list (by priority)