This type of problem is not unique to H3's. My Daughter's 2008 bug has had same problem since brand new. Finally fixed. Rather than an "X" the VW uses a pinch tube. After 8-9 trips to the dealer and her interior still flooded, all I had to do was cut the tube off above the "pinch". The gunk build up has little to do with how much your top is open. Just the regular dust and dirt getting washed down through the drains over time will do it. Many thanks to OP.

 

each time this comes up i try to test mine again. this time i took a 1.5 liter bottle of hot water and a liquid cleaner. it runs thru the front right now and i could see the suds, figure it might clean out any dust.
parked up hill and did the back. tires got a bath, good
so just to out do myself i got TWO bottles for a rinse and up front they drain fast, good.
in the back because i had so much i poured faster than before. thats a problem. the rear drain area is flatter and cant handle volume, tust a trickle. so the back seat /sides got a bath.
this truck is almost 5 yrs old, never had a drain problem, still dont!

i open only when moving and grease the seal 3-4 times a year. think ill do it today.

 

Huge thank you to original poster. Just saved me a ton of money.

I did however use too high of a psi as an earlier poster warned and blew the tubes right off of where they attach to the sunroof. Had water dripping through everywhere. Wanted to post so that if anybody should do that, it's not a huge reason to panic. (As I initially did.) Basically just need to get in under the headliner. Step 1. Take off the A pillar. (Remove the "airbag" plastic piece then phillips unscrew. That piece pops right off.) Step 2. Unscrew the visor (should be three phillips screws.) Step 3. Roll back the rubber door trim that goes up and around the frame. This should allow you to separate the headliner from the roof. All you need is enough to see where the drain tube separate from the sunroof. I only had to separate the headliner from the ceiling about 4 inches or so to fit my hand in there and reattach the tube to the fitting. It's the same procedure for both driver and passenger sides.

Hope this helps someone someday! I'm not a huge car guy and was out of sorts when I realized what I did, but really should be just another 15 minutes of work or so to fix it now that you know what you're looking for. Good luck!


-2008 Hummer H3

 

I haven't had an issue yet either. Good to know though. Thanks for your effort!

 

I appreciate everyone's advice..

Totally lost the grommet on the passenger side though. H3 is garaged until the new one comes is. Gonna try to look for it in the morning :-(

 

I can attest this is the fix if your moonroof/sunroof leaks. I finally did this fix today and I did indeed have a build up of gunk in there. Do not plan on this taking you ten minutes unless you are very skilled. It took me about two hours but I was not going fast. Passages side took the most time due to the access. Hardest part like said by others was getting the nipple back in flush. My nipple looked like someone may have attempted to fix it or drill it at the factory as it only had a portion of the x left. I finished the job and pulled the tube out which had gunk built up in it. Then I was able to push some hedge trimmer line thru it and out the top hole. Then I seesawed it a bit and twisted it as much as I could to get the gunk out. It was mostly fine debris in there so I'm thinking it just built up over time and mixed with water turns to fine mud. Driver side was easier but it's not behind the tach it's more behind and up above parking brake way up about the vent hight. Do plan on having some scrapes and bruising from passenger side from reaching in. Thanks to all before me for posting this. After the fix I was able to pour a pitcher of water at a pretty good rate in the trough and not a drop spilled inside and it flowed through the hole to the point where it had to gurgle for air. All flowed down and out of the car. Did that to both sides. I'm good now for a few winters if not more, if I keep the trough clean that is. Thanks again!! I don't post much but I read these forums almost everyday!! They are awesome!!!

 

I've got a very soggy front passenger floor board. Thanks so much for taking time to document the fix in such detail and with photos. Going to try it this weekend!

 

How exactly do you remove the passenger side 'A' pillar trim panel.

 

Try a search for "Removal of H3 Hummer A Pillar" and see what happens.

 

It's easy as pie. There is a little round cover almost in the middle of it remove that and unscrew the Phillips screw then pull off. For the side black piece of the dash open glove box there are two rivits under the glove box flap on right side. Push the middle of those in and simply remove. Then just pull off the small right side cover from the dash it's just held on by 3 clips. Good luck.