I did the scrubbing bubbles on a 124. I came at it from the blower side in the engine bay.

The smell of scrubbing bubbles did persist for a couple weeks...

In the OP's case, with a 123, I would try flushing with low pressure clean water directed through a 1/4" hose. Be sure your drain tube is not leaking!

Go to your garden center and look for a drip irrigation adapter to garden hose fitting. Put that on the end of your garden hose and use drip irrigation tube to flush.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech