Well, it’s a job I’d like to do as well, as my truck is also suffering from saggy britches. My temporary solution has been to use an office stapler and place a few well aimed staples to keep it from completely dropping away from the backing. As far as I know, I can tell you the rear jump seats are trivial to remove, if not a little heavier than you’ll be expecting. As far as the front seats I believe you should be able to lean the seats back enough without having to remove them. And THAT, should afford you more than ample amount of room to remove the headliner.
I’ve been thinking about removing mine and having it fiberglassed just for ease of cleaning and longevity. But that’s a project for when I’m satisfied with completing the mechanical maintenance that still lingers on the to do list.
So, just curious, what will you be doing exactly to repair your headliner?

 

You'll need a friend/extra pair of hands to slide the headliner out the tailgate aperture. It may help to begin by removing the upper half of the aperture seal to aid unclipping the centre rear of the headliner and reaching into the gap between it and the roof to separate the rear washer hose from the white connector. The hose is hot glued to the headliner backer board. The other end of the washer hose glued to the headliner backer board is connected behind the left front A-post trim cover.

Remove the front and rear interior lights the take a pictures of all screw positions and wiring connections and harness clips.

Take plenty of pictures as you progress.

Remove the interior lights' upper consoles - remember you'll need to reconnect the sunroof switch when you're ready to tilt it open so you can remove the six retaining screws attaching it to the tilt/slide tracks.

Remove the sun visors and tie a cable tie around the small electrical connection for the sun visor lights to prevent the connector disappearing into the roof cavity.

Remove the rear seat headrests.

Remove the glass sunroof panel, then carefully undo the ring of small Phillips screws sandwiching the sunroof surround to the plastic support in the headliner backer board.

After removing the upper A-post and C-post trim covers*, the four grab handles, the pair of circular headliner trunk trims and both rear speaker trim covers (D-post) remove the B-post trims (don't lose the small springs latching the upper front seat belt adjusters).

Fold the rear seat backs down.

Run the front seats to their foremost position and tilt the seat backs as low as possible (if you have manually adjusted front headrests remove them).

Take lots of pictures as you dismantle your car's interior trims so you'll have good references for when you're ready to reinstall your repaired headliner.

Now, with care two people can carefully tilt the headliner so it'll slide out backwards paying extra attention not to crease the sides of the headliner which cover the side-curtain airbags (where the grab handles are located).

Rob

*The lower halves of the C-post trim covers ("covering" the rear wheel arches) hide a pair of 8mm socket trim screws retaining the bottom edge of the seatbelt trim covers so don't just yank on the bottom of the upper trims thinking they're simply clipped in)

 

Impressive! I have a 2004 L322 with the Lux package and around 2015 I had my headliner replaced. The first trim shop called me back when they discovered the sunroof needed to be removed to release the headliner.
I found another shop that was able to do the job, but I did have to return for a warranty repair, the second shop did the job but after a week I heard a screw rattling in the area of the rear cabin lights and I think the sunroof stopped working. I was terrified, but they fixed it and said it was an easy remedy.
It sounds like an undertaking. I remember cleaning up some glue remnants from the old headliner’s removal.

You'll need a friend/extra pair of hands to slide the headliner out the tailgate aperture. It may help to begin by removing the upper half of the aperture seal to aid unclipping the centre rear of the headliner and reaching into the gap between it and the roof to separate the rear washer hose from the white connector. The hose is hot glued to the headliner backer board. The other end of the washer hose glued to the headliner backer board is connected behind the left front A-post trim cover.

Remove the front and rear interior lights the take a pictures of all screw positions and wiring connections and harness clips.

Take plenty of pictures as you progress.

Remove the interior lights' upper consoles - remember you'll need to reconnect the sunroof switch when you're ready to tilt it open so you can remove the six retaining screws attaching it to the tilt/slide tracks.

Remove the sun visors and tie a cable tie around the small electrical connection for the sun visor lights to prevent the connector disappearing into the roof cavity.

Remove the rear seat headrests.

Remove the glass sunroof panel, then carefully undo the ring of small Phillips screws sandwiching the sunroof surround to the plastic support in the headliner backer board.

After removing the upper A-post and C-post trim covers*, the four grab handles, the pair of circular headliner trunk trims and both rear speaker trim covers (D-post) remove the B-post trims (don't lose the small springs latching the upper front seat belt adjusters).

Fold the rear seat backs down.

Run the front seats to their foremost position and tilt the seat backs as low as possible (if you have manually adjusted front headrests remove them).

Take lots of pictures as you dismantle your car's interior trims so you'll have good references for when you're ready to reinstall your repaired headliner.

Now, with care two people can carefully tilt the headliner so it'll slide out backwards paying extra attention not to crease the sides of the headliner which cover the side-curtain airbags (where the grab handles are located).

Rob

*The lower halves of the C-post trim covers ("covering" the rear wheel arches) hide a pair of 8mm socket trim screws retaining the bottom edge of the seatbelt trim covers so don't just yank on the bottom of the upper trims thinking they're simply clipped in)

 

Thanks for the detailed writeup.

 

Seriously Rob, thanks for that write up! Looks like sticky material to me! It’s something most all of us face with these trucks. It’s definitely no small task but with the instruction you’ve provided removes alot of the mystery in removal out of the equation. Gives me hope I can one day get mine out and repaired.

 

Thanks, Rob! Sounds like it's unnecessary to remove any seats. Fingers crossed they didn't change much between the model years (and for this area of the L322, I doubt it). Will report back when I'm done.

 

FWIW, depending on how careful you are, you might consider undoing the four bolts attaching the front seat tracks to the floor and being able to tip the seats even lower whenever you plan to reinstall the repaired headliner.

It's really important to have adequate clearance on either side of the headliner/tailgate aperture when you're sliding it back through the tailgate aperture (at an angle) to avoid damaging the headliner.

Rob

 

I had to unbolt the front passenger seat to get it flat enough with the rear seat folded down. You need to get the passenger side as low as possible. The headliner is only a few inches less than the diagonal opening length of the rear hatch.

The B pillar trim coverings were the hardest to remove and reinstall with the seat in place on the driver side. It's doable but unbolting the seat gives you the few more inches.

The shop manual says remove the passenger seat because it's easier to write. The unbolt procedure is: move the seat forward to remove the rear bolts, move the seat back to remove the front bolts, move the set forward again and recline, disconnect the wire and position the seat. Redo last 2 steps till in the right position. Maybe just taking out the passenger seat is easier.

 

I finally started yesterday afternoon... this job sucks! I ended up pulling the seats; unneccesary, but honestly that's probably one of the easier steps.

I almost finished getting all of the old foam/glue/residue off of the fiberboard, then ran out of acetone. It's all downhill from here I'm sure

 

If you haven't already tried it, simply use a wire brush to remove the remaining foam/glue detritus.

Rob

 

If you are going to the extent of taking it out, may consider having the pillars also recovered as most times you likely wont find a perfect match. when I had mine done took it out and had all the trims recovered except the visors. in hind sight I should have done mine black instead of the original tan color, but it came with tan so thats what I went with on mine.