I just completed a citric flush on my 75 300d OM617 (w115 car) and flushed and backflushed many times and also used air to blow out remaining water. Yesterday, I noticed when bleeding the system that I thought I detected a rush of rust colored water and wondered since I did not open block drain is it possible to trap rusty water somehow in spite of flushing/backflushing? I must have flushed about a dozen times until water ran clear. Someway that water can be trapped in the circuit near the block drain? Thanks!

"Trapped" probably isn't an accurate description. It's more like "not inclined to flow up hill."

Don't be lazy; pull the plug.

Heater matrix?

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

That makes sense, solids sitting low - betcha a bunch crap is about to leave the block drain, last time I do that! Thanks!

Service manual says to only do the citric acid flush after the system has been deoiled whether there is any indication of oil in the system or not.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles

yep, did that with Shout as before -