Hi Stuart, So sorry to hear of your predicament. I promised myself to do a more complete write-up of the process we went through to replace the pipes but I've not got near to it yet.
The short answers to your questions are here:
a) I managed to get the pipes to go through the grommet after removing the old pipes and roof sensor wiring cables. No body panels were removed.
b) Our roof was stuck in the "up" position so we didn't have to lift it up manually. I made up a wooden support and at the appropriate moment I released the hydraulic pressure and the roof gently sat down on it without any drama.
c) I got the sealant out of the grommet by a laborious process of working it by hand until it came out.
And here's the longer answer ...
We have a 2013 California SE (T5), and all of the comments here refer to our van. I don't know how much would be relevant to earlier or later models (eg T6 Oceans).
Bear in mind that the failure in our pipe was next to the grommet, and it was in the pipe which gets pressurised to lower the roof. So the oil came out quite close to the grommet and I daresay it made the grommet / sealant fairly well covered in the oil, which may have helped in getting the sealant out of the grommet.
For background, it is my belief that the damage was caused by a repair at Breeze in Southampton in January in the same area of the roof. The van had been in Breeze in the autumn of 2019 for the cam belts to be changed and they spotted roof corrosion which eventually resulted in the roof being treated under warranty. Just before sending the van in for the roof work (which I am told is carried out in a specialist body shop somewhere and not at the dealer) we noticed that there was water ingress at the top of the A pillar which manifested itself as a wet roof lining and wet carpet under the drivers feet / pedals area.
After the van came back from the body shop the chaps in Breeze looked at the water ingress issue and told us that they had to fix a fault caused by a bodged repair by a previous owner. No further details but I understood that either the grommet or the small drain pipe had become blocked or disconnected or something. We have not had any further water ingress after they "fixed" it.
After this repair, the roof had been up (and down, obviously) twice before we found that it would not go down any more. I could hear the hydraulic oil bubbling and smell the oil and I found oil leaking at the front of the roof at the top of the A pillar - where the grommet is.
Breeze could not look at the van for 3 weeks and anyhow the roof was stuck in the up position and the van therefore not driveable without messing with the hydraulics. I was reluctant to let them charge me a 4 figure sum to give them the opportunity to mess up the van again. So I decided to tackle the job myself.
I removed the cab head lining which was one of the tricky parts of the job. The post by TripleBee (here:
https://vwcaliforniaclub.com/threads/as-promised-changing-the-electrohydraulic-roof-pump.33489/) was really helpful. He misses one or two key details though, including the laborious process of removing the fittings and especially the central control console. I had to remove the interior mirror, for example, which has two cables attached to it. The frame which the sliding roof locates into (sorry - I don't have the correct nomenclature) was probably the most difficult part to remove (and replace) because it is glued in place and also has a pop rivet at the rear of each side. There are other threads (such as this one:
https://vwcaliforniaclub.com/threads/how-to-remove-headlining-around-central-unit.34908/) which give more details of this. I did it with the roof up. It would be even more difficult to do it with the roof down, and the roof lining can't be completely removed without removing this frame.
As I mentioned, our roof was stuck in the up position. A thread on here somewhere (can't find it just now) recommends using an acro to get the roof up. My father in law is a retired builder and he just laughed and said that an acro is massive overkill, is very heavy and will make nice dents in the floor and the roof. The thread did mention spreading the load with plywood but father-in-law says you would need really thick plywood to be sure not to damage the van.
In the event I made a tee piece from some 2 x 2 timber (maybe 2.5m long) and some 9mm plywood at the top and bottom to spread the load. When I had to release the hydraulic pressure the roof rested gently (about 2/3 of the way up) on the support. I didn't try to move it too much but I got the feeling that it would be possible to manually push the roof up once the pressure was released. That might be a 2 person job.
The sealant was already looking like a bodge job after the work done in Southampton. I removed it by initially cutting it back carefully with a stanley knife to get the excess off and leave just a thin layer near to the cables and grommet. By working the grommet and cables / pipes (which were at least a bit oily) with my fingers I eventually (bit by bit) was able to get the sealant out of the grommet hole. When you order the pipes from VW they come in a pair, so I decided to replace both of them. After removing the pipes I cleaned up the inside of the grommet as best I could using a solvent (I used IPA or iso-propyl alcohol), with just the roof sensor cables left behind. If you are replacing the roof sensor cables then you will have an empty grommet hole and this will be easy.
You can get some sealant softener for use in bathrooms and I was tempted to try this at one point but I would worry about damage to paintwork etc.
That's probably enough for one posting and I hope it is useful for you. I have a ton of other tips for you if you decide to tackle this job yourself and I also have a mostly full bottle of the hydraulic oil. Good luck with it and feel free to ask any other questions you might think of.
