Yes, there is an oil cooler drain plug

[fj bertrand]

Changing the oil in the new to me 220d (you just have to love those pot oil fillters, eh?) Anyway, lo & behold, on the oil cooler there is a drain plug, to get all that nasty oil out. sure enough oil did come out...

Now, on my 240d and 300d there is no drain plug on the cooler. Wonder why the change? Perhaps the difference between 1971 oils and 1984 oils characteristics maybe later on MB oil people decided the oil cooler didn't have to be changed, or they just cut costs???

[HIDGolf]

maybe the oil cooler is mounted high enough that it all drains downhill to the oil pan so it doesnt 'pool' in the oil cooler?

Is the oil cooler on the 71 a radiator type or is it a coolant/oil heat exchanger?

[t walgamuth]

it is a radiator type. all of them are very similar except the older ones had the drain plug. a word of caution, the tanks on the oil coolers are very fragile and the fitting with the drain plug and the line fittings can very easily be twisted out.

[fj bertrand]

No it is the standard fin type adjacent to the radiator. I was kind of shocked to see it as there have been threads debating whether or not to open the bottom oil line to drain the oil out of the cooler. For want of a better reason, I think they eliminated the drain plug for economy or because the oils have gotten much better over the year and a little comingling of used and new oil is not so
bad...

[billrei]

Originally Posted by fj bertrand

No it is the standard fin type adjacent to the radiator. I was kind of shocked to see it as there have been threads debating whether or not to open the bottom oil line to drain the oil out of the cooler. For want of a better reason, I think they eliminated the drain plug for economy or because the oils have gotten much better over the year and a little comingling of used and new oil is not so
bad...

Typical of Mercedes post 1967 (when they cheapened the W108) they saved $0.05 so they went with it. Once on that road plastic cooler tanks etc. were a no-brainer.......Even gasser Mercedes in the early 1970's have the oil cooler drain not to mention a radiator drain as well.

[phantoms]

Later years MBs have a radiator drain. It's usually a screw out drain that also server as one of the lower mounting nipples.

[Hatterasguy]

According to me service CD my cooler holds a little over 1/2 a quart. I am not sure of the exact number but if anyone wants it I will look it up. The CD says the cooler does not need to be drained and for 1/2 a quart out of 8 it probably isn't worth it.

[dkveuro]

Originally Posted by t walgamuth

it is a radiator type. all of them are very similar except the older ones had the drain plug. a word of caution, the tanks on the oil coolers are very fragile and the fitting with the drain plug and the line fittings can very easily be twisted out.

As a word of warning.. ..Do not attempt to unscrew the lower oil line fitting on the cooler.
I have changed out many engines and the cooler lower fitting is the only thread that consistently siezes and is grief to repair.

I now remove the cooler complete or leave it in the car and flush it out with solvent....depends on the engine failure.

The alloy threads seem to weld to the line nut after 15 or more years in service ...Leave well alone !