I have been trying to clean the bottom of a '86 Bronco and there is baked on mud on the bottom especially on the transmission and on the transmission protection pan (or whatever the pan the transmission rest on is called). I tried pressure washing with my 2500 psi pressure washer yesterday which got a lot of dirt off, but in some places even point blank pressure washing is not taking it off well. Do y'all have any suggestions on how to remove it?

Some of those places like above the transmission are hard to reach with a wire brush as well. I am planning on getting a pressure washer gun that is short for reaching into those places (mine is at least 3' long so it is hard to angle up enough with the truck sitting on the ground), but even still it does not want to come off.

I plan on cleaning enough to be able to spray the entire undercarriage with something like RustBullet to convert the current rust (which there is a good bit of, but its not structural) and protect the rest of the undercarriage.

I appreciate your help on the subject!

 

When the mud is removed the metal looks dry so I assume the reason the mud is so hard to get off is because it is grease soaked. Here is a pic of some of it.