4Runner Gen 5 Sunroof Drain Blockage Fix
I have a 2011 SR5 4Runner with 165,000 miles and I love it! Never a problem with the exception of general maintenance, most of which I perform myself. Recently I ran into the same problem as most of you here. Mildew/Mold smell and water on my floor. I'm going to share a thorough explanation on the cause and how to fix it.
Contrary to other posts I've read, car manufacturers do expect your sunroof to leak. With the inevitable dirt/pollen corrupting the seal of any sunroof over time, the manufactures designed a drainage system to redirect the water. There will always be four holes in the sunroof connected to drain tubes directing the water out and underneath your vehicle. The cause for the water on your floor is these drain tubes get a clog and the water can't escape causing a backup that spills out of your sunroof and down onto the headliner. From here, it flows down the pillars, usually the A pillars and down under your floor's carpet where it seeps up.
To fix it, you'll need to remove the running panel at the bottom of your doorway. Then unscrew and remove the triangular panel found to the left of the foot rest on the driver's side and under the glovebox to the right on the passenger side. You'll find a tube (each tube is color coded to reflect which sunroof hole it should be connected to), driver's side is pink on my 2011 and passenger side it white. Pull it up and out of the hole where you'll find them. Pull out the white filter plug at the bottom of each front tube and clean them. Don't reinstall them yet. Open your sunroof and locate the front left hole and the front right hole. Take a sheathed 14 to 16 gauge wire, thick weedwacker line, or better yet, curtain wire (https://smile.amazon.com/Shappy-Meter-Curtain-Self-adhesive-Hooks/dp/B075LHFBVX/ref=sr_1_8?keywords=curtain+wire&qid=1566928050&s=gateway&sr=8-8[/URL]) and push it through the holes until you see it come out the bottom of the tubes. Rake it back and forth several times before pulling it out. While keeping the end of the tube bent and pointed outside the vehicle's door, poor a couple quarts of water down the front holes in the sunroof. You may want to use a funnel for this. Replace the white drain tube filter plugs and reinstall them back into the holes where you found them. Poor more water down the drains and ensure its emptying out the underside of your vehicle. If you have an air compressor, put an extension with a rubber tip on your blow gun and blow out the lines using around 30-40 PSI. Replace all the paneling you removed.
The rear drain hoses are a little more difficult. One cannot reach the drain holes to the rear of the sunroof from the sunroof opening so they have to be cleared from the exit ports. The end of the left rear hose is simple if you have a Gen 5. Its location behind the pop-out panel where you would find your truck's jack. The hose is blue and can be accessed simply by popping it out of its black fitting. Run your wire as far as you can. I actually had trouble getting it past 2' as I believe I found a significant bend in the tube and the 14 gauge wire wouldn't bend past. Curtain wire would have definitely worked better but I decided to use my air compressor to blow out the line instead.
The right rear drain hose was more difficult to locate. Found it by removing the guard panel in the wheel well located adjacent to the right rear fender. After removing this, you'll find the drain hose exiting between the fender and the inside metal housing. Because of another bend in the hose, I once again had trouble getting more than 2' of my wire into it. I defaulted back to my compressor to blow out the line. Its helpful to have a helper on hand who can either blow out the line while you listen for the exit of compressed air at your sunroof or have them listen while you blow it out.
Test the rear drain ports by parking on a slight incline or driving up on ramps under your front wheels. Conduct the water test on each side and ensure you have a successful flow out and under both sides of the rear of your vehicle. If you do, replace and button up all panels. Congratulations on successfully repairing your sunroof leak!
If your carpet got very wet and you cannot get rid of the smell, you'll need to take it a step further, as I did, and remove more paneling and seats, and pull back the carpet to dry out. Get rid of all moisture in the carpet and padding and clean any mold/mildew you find. Then clean your carpet with a good, dry auto carpet cleaner. Reinstall everything when you're satisfied with the results of your remediation treatment.
Hope this post helps! For Gen 4, you should find this video helpful;
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