Please, assist! A bolt was missing from the oil cooler of a 2012 MLI 350 CDI V6.

[MBcarOWNER]

Salutations to all those brave souls tackling the infamous oil cooler failed seals dilemma.
I took the oil cooler off and, in an attempt to prevent any fluids from leaking out, I clumsily turned it upside down. I am absolutely devastated since not a single bolt has been located. Over the cooler oil galleries and out the front of the engine bay, they spilt. Everything in the oil and coolant galleries has been vacuumed and examined with a borescope, but I still haven't found anything.
additionally verified the entry points.

To cut a long story short, I should have ten bolts for the oil cooler, but I only have nine.
Is anyone familiar with this? Are the bolts tiny enough to become trapped in the oil galleries? Just curious.
I was hoping someone with more expertise on the subject might tell me whether there's a method to pressurise the oil galleries; I'm assuming that when I turn the engine over, pressure will go from side to side.
My brain is in utter disarray, you guys. In need of assistance

[MBcarOWNER]

https://www.ebay.co.uk/sch/i.html?_nkw= ... olid=10001

[MercedesMan98]

I thought it had escaped the exhaust manifold.
A decent rule of thumb for stopping this issue is to stuff rags into all the ports and other openings.

[MercedesMan98]

https://www.ebay.co.uk/sch/i.html?_nkw= ... olid=10001

[veroguittar]

Whoever has ever worked on an engine has probably done something similar, but it's a bit late now. I inserted a little socket extension into the extremely tight engine bay when replacing the sixteen spark plugs in my AMG, which was my most recent project.

I finished the task and drove the car up and down our quiet dead end road to attempt to get the Ba$tard thing to roll somewhere sensible while trying to fish it out (magnet too weak). Then it landed onto the undertray.


Lifted the front end and removed the undercarriage; no chance. It rained while I was on the road.

[DivineStripe]

If I were in charge, I would have kept the tray in place until I needed to take it out.From the time I changed my radiator a month later, I forgot about the 10mm ring spanner.

[matthewlightburn]

Hey there, buddy!
Is it possible that it landed on the floor or the undertray after bouncing?

[veroguittar]

I considered it, but it was behaving erratically—it wouldn't go where I wanted it to go, despite its clumsiness and loudness.