Holiday coolant flush w124 300d
To access the block drain do i need to have the wheel off?
Whats the best way to flush all the coolant, should i have the block open at the same time as radiator hoses?

No need to remove the wheel to drain the block. First, drain your radiator - there is a petcock on the bottom, or you can remove the hose if you like. Then move to the block. On my '95 the drain is designed so that you can attach a hose so you don't have to take a mini coolant bath, but I never have and it isn't that bad - just don't lay under it while you loosen the drain.

Here is a recent thread with some pics: URGENT: Block heater connection OM603 Location

To flush, you can refill the system with distilled water (can be bought at most any grocery store or Wally-World). Run for a bit (with heater on), allow it to get up to normal operating temp, then let it cool down and drain again. Fill with MB brand (expensive) or Zerex G-05 (cheaper version, same stuff). Best to point your car uphill when you fill it back up- steep hill works well, or at least on some ramps. Start by filling through the reservoir, when that fills up, undo the upper hose at the radiator and fill through there until you can't get anymore in. Take it for a ride to get it circulating - don't be surprised if the temp wants to go above normal at first - you may need to burp some air out - add more coolant as needed.

Merry Christmas!

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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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"Back off, man. I’m a scientist” ~ Peter Venkman

If it's a holiday coolant flush I suggest you refill the system with eggnog. Maybe some rum too if it runs hot.