Hi all,

I've recently acquired a 1984 300D Turbodiesel, and it's been driving rather well for the most part. I've been poking around the engine bay and--as a complete mechanical novice--have a few questions. I've been obsessively reading up on these cars and this forum has been an invaluable resource!


Checking the dipstick, it seems like I have a little too much oil. How much of an excess (volume-wise) does this represent? Is it something that should be rectified immediately?


Checking the coolant. Is a clear green color correct for the coolant?


What is this, and is it OK for it to be detached? At first I thought that it looked like the primary fuel filter (!), but then checked near the fuel pump:


Primary filter is there. Needs to be replaced, along with the hand-primer and some of the fuel lines.

I've been noticing a bit of white smoke at idle (dissipates once the car starts driving). Planning on doing a valve adjustment soon, as well as changing the fuel filters and flexible hoses. Hopefully that should get things running better!

Yeah, if you can remove some oil, good.

These cars like orange coolant, aluminum friendly.

Appears to be electrical, not sure. One of the vacuum orifices have been plugged, I bet your door locks don't work.

Yeah, new filters and a new primer are in order. I wouldn't worry too much about the oil smoke, but when you adjust the valves, install a new gasket there too.

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83 SD

84 CD

That's maybe 1/2 a quart of oil. Did you change it when you bought the car?

Green coolant is not ideal. Not instant death, but not ideal. The best bet for coolant is Zerex G-05. You may have to ask for it at the local auto store. Some keep it "in the back".

That cable doesn't look like a factory piece I've ever seen.

As mentioned your vacuum system will need some help. Do your automatic door locks work? How about the climate control system?

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1979 300D 040 Black on Black - 1985 300D Maaco job (sadly sprayed over 199 Black Pearl Metallic) on Palamino

http://i.imgur.com/LslW733.jpg

The Baja Arizona Oil Burners Send a message if you'd like to join the fun
Left to Right - UberWasser, Iridium, Stuttgart-->Seattle,, mannys9130

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I wouldn't worry too much about too much oil. I did that a few times by checking the oil cold and then putting too much in. The trick is to check while the car is up to operating temperature.

Green color coolant is fine although the system should be regularly flushed.

On pic #3, is that coming from your instrument panel? It looks like your speedometer cable. Are you getting an accurate speed rating and is your odometer/trip timer working?

Dkr.

The oil level may be fine, depending on when you checked it.


Proper oil level check is around 5 minutes after shutdown for MB.

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The shop that changed the rear trailing arm, axles and bushings did an oil change as well, so that may be the source of additional motor oil. I'm not sure about the type of oil they put in, so I'm thinking of changing the oil filter as well as switching to Mobil 5W40 Turbodiesel Truck oil when I do the valve adjustment.

Alright. We'll get that changed out ASAP, then.

Great! I'll assume it's not critical, then.

None of the above, though the car is getting a new set of ceramic-copper fuses today. It's been displaying a certain amount of endearing (but ultimately annoying) electrical quirks, and a quick check of the fusebox revealed several fuses that had reached the end of their useful lifespan.

The transmission has also been displaying some occasional hard shifting, which leads me to believe that it isn't receiving enough vacuum. I'd like to ultimately reduce the vacuum system to a bare minimum--enough to ensure proper operation of critical functions, and plugging off the rest.

Regarding the light smoke at idle and the poor(ish) fuel economy, I'm hesitant to come to any conclusions (and/or get unnecessarily concerned) before I do a valve adjustment and replace the leaking injector fuel lines.

Ah, good to know. Oil was checked cold.

Odometer and trip timer are working. Speedometer is a bit shaky from 0-15 MPH, but stabilizes once I reach high speeds.

Fuel gauge is a little wonky, though. Seems to have a margin of error of about 1/5 tank at any given time, as flutters between 1/3 and 1/2 tank while driving. Obviously I'm unsure which reading is correct, and it's not the most optimal situation for assessing my fuel situation

can you take closer pictures and some from different angles of that thing thats been disconnected? i'm intrigued.

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1981 NA 300D 310k miles

The shop that changed the rear trailing arm, axles and bushings did an oil change as well, so that may be the source of additional motor oil. I'm not sure about the type of oil they put in, so I'm thinking of changing the oil filter as well as switching to Mobil 5W40 Turbodiesel Truck oil when I do the valve adjustment.

The car is getting a new set of ceramic-copper fuses today. It's been displaying a certain amount of endearing (but ultimately annoying) electrical quirks, and a quick check of the fusebox revealed several fuses that had reached the end of their useful lifespan.

The transmission has also been exhibiting some occasional hard shifting, which leads me to believe that it isn't receiving enough vacuum. I'd like to ultimately reduce the vacuum system to a bare minimum--enough to ensure proper operation of critical functions, and plugging off the rest. Door locks don't work, and neither does the climate control. But that could be due to the fuses, as well.

Regarding the light smoke at idle and the poor(ish) fuel economy, I'm hesitant to come to any conclusions (and/or get unnecessarily concerned) before I do a valve adjustment and replace the leaking injector fuel lines.

Coolant will be changed ASAP.

Will do!

I'm interested in the cable too. The outside looks like the speedometer cable as well as the location, but the connector makes it look like something electrical.

When I bought my current W123, it had the remnants of an alarm system which had been partially dismantled. There was a smaller connector like this that was disappearing behind the firewall. Is it possible it was for an alarm?

Dkr.

Here we go!

Took the opportunity to replace my instrument cluster with one that actually has the clear plastic window Thanks uberwasser for the guide on ifixit!

Before


During


After!

Off to a good start!

__________________
1979 300D 040 Black on Black - 1985 300D Maaco job (sadly sprayed over 199 Black Pearl Metallic) on Palamino

http://i.imgur.com/LslW733.jpg

The Baja Arizona Oil Burners Send a message if you'd like to join the fun
Left to Right - UberWasser, Iridium, Stuttgart-->Seattle,, mannys9130

Visit the W123 page on iFixit for over 70 helpful DIY guides!