The 1980 300D has no expanion / overflow tank connected to the radiator.

Having done a lot of work on other models recently and realizing how important
an expansion tank is, I decided to add one .

So the next few weeks will tell me if it has the desired result.

Even with a new radiator cap I felt I was losing coolant slowly.
And it does dribble out through the overflow hose.

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

The only reason to have an overflow tank is so the rad can be shorter and the hood line can be lower. Leaving some space for the water to expand into in your rad may stop the overflow dribble.

__________________
1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

I wish my 240D had one. Its routine water level -- the point it dribbles down to every single time -- is lower than the tank top, so I can't ever see if it has water in it or not.

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

Are you having an overheating problem?
Are you sure the water loss is all from the overflow?
Is your rad cap holding the correct pressure?

__________________
1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

No overheating ever on this car; in fact, I have to work just to make it raise higher than 80 with the a/c off and the mark above 80 with the a/c on. 100 or so, on a 95 degree ambient day.

I'm just now starting to suspect I'm losing water somewhere; I'll start my own thread when I get around to addressing it.

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL