This past weekend, I installed my mud flaps. Did you know that the X can hold about 10 pounds of GUNK behind the rear wheels? When I undid the clips on the rear fender wells, I looked behind them and saw that the area was full of rocks and dirt from 70K miles of Pennsylvania driving.
I took the opportunity to wash it all out. You can see the mess left on the driveway.










I would suggest that the next time you have your wheels off, pop the plastic clips out and take a look back there.

 

or just remove your liners forever....

 

I was going to start a thread about this when I did my crash beams. My rear had about ten pounds of rocks and shiz

 

yea..gonna check that spot next time I wash the car lol

 

Thing about mine was it was not visible until I had the rear completely off. Then take a screwdriver to the mounds. I had never had it off before but I will periodically check it now.

 

Damn!

 

Is it possible to properly drill some holes beneath the bumper to prevent the gunk from accumulating?

 

There actually is a hole on each side. I'd say about 1/4" diameter, right at the bottom corner. I'm assuming mine got clogged up over time.

 

...and now pull the plastic covers (behind the front fender wells) you see just forward of the front doors (when open).

I pull out what leaves & crappe' I can by hand then wash with hose....