Probably sunroof drain. I know you said door seals are ok, but check for small gaps maybe too: I'm in Canada and couple days ago we had warm weather for first time way above 0C and my rear driver side passenger door wouldn't open smoothly because the weather stripping had shifted to the point that there were gaps which could let water in. I had to reposition the weather stripping a few times before it sat right. Another one-off on my car was the grommet-like rubber in my rear hatch door at the top (roof) that feeds wires had popped out and was letting water into the headliner; caught that at a car wash, popped back in from outside, not related to your problem though.

Not saying this with the tone of a prick, just cover as much as I can to help with cause we all make silly mistakes, was the rear window possibly left open a crack by any chance? Maybe hose down the car heavy from outside if you have doubts

Waiting for other to chime and help because rear driver's side only seems to be the rarest in my experience with sunroof drain issues, but others have been around this platform and forum more and have seen more.

In any case, my video covers checks for both the front and rear sunroof drains through the sunroof tray, so it might help for testing if the other members' suggestions don't solve your problem earlier

Others please chime with your input, I'm not sure what I've posted here is correct to help in this particular case

 

Water is hard to trace because a small leak will just run along the metal and not drip and make everything around it wet. But I'd agree sunroof drain is most likely or a failed windshield seal. At least your floor doesn't have a hole in it....

 

welcome to P1 life

 

As mentioned, it is probably the front sunroof drain. The drain hose will fall out of place and drain into the car.
The above is a great video to watch for Sunroof drains.
The floor carpet is 3 inches thick of foam. This is for sound proofing from road noise and keeps extra heat out. This foam is a spouge and soaks up lots of water. The driver seat needs to be unbolted, set back as far as possible and pull out the front carpet to dry out. Removing the driver seat from the car is not that easy, I leave it in the car. After removing the front carpet, move the driver seat as far forward as possible. Remove the rear seat bottom. The rear carpet is soaked also. It goes across the floor from left to right. Unbolt the pass seat and set it forward to get better access to removing the rear floor carpet. Hang the carpets up to drip dry. It will take 5-7 days to completely dry out. Get premix Odor Ban from Lowes/HomeDepot and spray on the metal floor and carpet bottoms before installing.

(259) How to Fix a Leaking Sunroof Drain and Wet Floors in 2006 Volvo S40 - YouTube

 

I'm up in northern CA, and due to the heavy rains I just had this same issue, except mine was the passenger rear footwell. I believe the rear sunroof drains are clogged (front carpet is completely dry), but they are a bit more complicated to get to than the fronts. I have to wait for the weather to clear up long enough for me to pull the seats and take the carpet out. Car smells all mildewy now which is not awesome.

Check your front drains like the video above shows and see if the water drains out. If they're plugged, you'll need to get to the little nipples at the firewall and massage them to break up the clog. The nipples are this stupid cross pattern that clog easy. I would recommend getting rid of them and running straight hose through the firewall to keep this from happening in the future. If it's your rear drains you'll need to tear apart the rear pillars by the rear seatbelts to access the drains at the rear wheel wells. I found a video on YouTube, but I'm having trouble finding it again. It doesn't look like a fun job ☹.

Good luck! Hopefully it's just the front since that's much easier.

 

Thanks for everyone's suggestions. Updates: the floor under the rubber mat in the driver's footwell is also damp...drying needed. A couple years ago we had moisture on the front passenger side and it turned out that the front drain hose from the sunroof (due to age, heat?) wasn't reaching the lower part of the drain hose. The dealer extended the hose; problem solved. As to another video comment, yes our V50 was parked at a steep incline (front high) during the storms. I'm having trouble even seeing the rear drain hole. Work in progress. I haven't pulled any panels yet.

 

I had this happen with my S40 with the passenger side rear footwell. The end of the drain tube in the A-pillar came out of the hole it drains out of in the firewall. It leaked down the side of the front passenger footwell and it pooled in the rear since it’s lower than the front. It’s pretty rare to have the rear drains go bad from what I’ve heard.

 

The sunroof drain hoses get hard and can slip off fittings. Also the rubber + valve at the end of the hoses can get clogged or even gummy and clog. I had a bunch of water in my car and had to pull all the carpet out to dry it out. It provided a great opportunity to really clean the carpet. I replaced the front drain hoses with clear hose from home depot. There is a video around showing how and has the size hose to get. I also eliminated the + valve at the ends (for better or worse). I have had no problems since (knock on wood).

 

Good info. Thanks. Our V50 is also Passion Red with the Dynamic Trim Package. I saw the video with replacement hose specs. Car is in our garage. Tomorrow I will pull some panels and do some water pouring. My sense is that pulling the carpets (with their bonded under foam) is a very big job.

 

Oops, allow me to add. I haven't yet found the drain hose ends with the notorious cross-ends that need removing.

 

The drain hose end is not easy to see. In the above V50 video at about 27 minutes it shows blowing water out thru the drain tube. With the hood cowl off, you need a mirror to look up under to see the drain tube end. Blowing out with shop air will work. Do not pull this elbow tube out from the inside. It is almost impossible to reinstall it. The hole in the car body metal is off to the side some. The red circles shows where the drain tube outlet is located. If you remove the hood cowl, be sure to turn #1 1/4 turn. The bare windshield glass sticks down. The plastic arm of #1 is up under the glass. If you pull up w/o turning #1 locks, you will crack the windshield glass.

 

Finally got around to pouring some water down the driver's side drain. Nice gurgling sound. And the water dripped out inside the cockpit just in front of the hood latch. Will replace the front drain tubes. Really appreciate everyone's input. Extremely helpful.

 

Here in Oceanside CA we actually had a hail storm this morning! Couldn't drive to my garage so I've starting removing panels, rear seat bottoms as well. Things are wet. I'm thinking the entire carpet will have to come out. Front seats as well? The job appears to be expanding beyond my personal skill level.

 

I had heavy water under front carpets. Yours seems to be more extensive. If you don't have time/skill for full removals, maybe try a similar technique to what I did to try without removal first. I made a part 2 video posted below last year as well. If you can get into all areas you have water from enough angles, you will dry it a lot with hair dryer.

Will have to be creative in the rear carpets as mine only shows the front BUT if you access in far enough under front seats between the seat mounting rails you can get some hair dryer action towards underside of carpets in the back (mine was well under the front seats, this may be back-breaking to a degree for some though).

Maybe find a video for prying up just the edges of the rear seat carpet to allow easier hair dryer access to that area.

I posted a photo on my instagram at the time which is still there showing that after the hair dryer in order to get the final amount of moisture out, I left carpets pried up with short sticks to hold them up, and left all the doors open on the driveway for about 8 hours. Some baking soda in cups in the cup holders for a few days after that got rid of the slight mold smell too.

 

I found the driver's side tube disconnected from the grommet that joins the hose to the outlet. Even after using compressed air, water won't flow onto the ground, nor will compressed air pass through it. I tried forcing something thru it. No luck. To get to the underside of the grommet I'll have to remove the wiper blades and the inside cowl??

 

Yes, but that's easier than it sounds. Job takes like 30 minutes to an hour. Those cross section nipples are the biggest pain in the but. They plug with just small particles of dirt. I'd strongly recommend getting rid of them all together.

 

Good info, thanks.

 

Job took me 2-3 hours, and that's just to get it all apart. Given the V 50 living outside for most of its life, every plastic fastener broke. I had to use a puller to get the wiper arms off. Given the wiper arm parts on the driver's side, I can hardly get my arm inside to just touch the end of the drain fitting. I successfully cleared the driver side drain and reinstalled the old pipe...for now. The water drains well - hurrah!! I'm going to have to get professional help to pull the interior carpet for drying. The front driver's side is totally soaked underneath, whereas at the rear I can almost lift it completely so as to wedge a prop to facilitate drying. I really appreciate the community's help!!😁

 

Update. Deciding that the job was beyond my skill level, I filed an insurance claim and the V50 is now at a local collision repair shop. First response? They want to total the vehicle. Water damage repair is a no-no, per the shop. Air bag parts, the seats, etc., can't be "fixed" by drying out the interior. Tough call for a vehicle with only 101,000+ miles. Stay tuned.

 

End of the story. USAA offered us just over $7,000 settlement after declaring the V50 a total loss due to the water damage. Great car for which I have detailed O&M records since new. Purchased this V50 from Diplomatic Auto Sales in MD; delivered to a dealer here in CA. Order placed 6/14/2004. Delivered in Nov 2004. Total price new: $32,275. So after almost 19 years of service, we recovered about 22% of the purchase price. As the saying goes, "gone but not forgotten."

 

Volvo friends and neighbors - no reaction to my insurance company (USAA) and their shop NOT being willing to repair our V50? I had the option of taking the "total loss" V50, drying it at another shop, and putting in place a salvage title. Honestly speaking, after getting almost 19 years of service from the car and considering that it was my wife's daily driver, this wasn't a viable option. California is a legal nightmare state. Hopefully some of you outside of California with similarly flooded interiors will fare better than we did.

 

Hey, been away from forum fro a bit, glad some of the tips people provided helped but not happy about the result, sad to hear the car is gone. If you are still active on the forum, discussing this a bit more would help others in the future.

In your initial posts, it wasn't clear that your seat and airbags were damaged by the water. Can you give more info on what was wrong/ not functioning with the the car after the water made it into the carpets?

 

Thanks for asking. Your V50 is similar to one of the comps that showed up in the 15 page, CCCOne Market Valuation Report prepared for USAA that valuated our V50 at $7,259.25. Essentially, there was nothing wrong with the car from my viewpoint. Everything electrical (eg., power seats) exposed to water worked just fine. CA is a very litigious state. The body shop didn't want to remove/dry/reinstall the interior because they told me they'd be responsible for the car "forever." Underwater? The seat motors were underwater, but the shop pointed out that the side airbag connections had been compromised as they were under the carpets on the floor, so also under water. The point was made that maybe next week, or maybe a year from now, there could be a problem. Apparently as a policy matter, the insurance company simply doesn't "fix" water damaged cars. If our Volvo was new or only a few years old, they still would have declared it a total loss. We could have bought back the car, obtained a salvage title and "fixed" it, but all in all, given having gotten great service for almost 19 years, we decided to let it go. As my wife's daily driver, I simply couldn't risk future problems. New battery, lifetime Koni shocks and more, but that was then. Now - it's gone. Tell you what, after realizing that my wife's Thai CDs were still in the changer, I drove to the COPART yard near the Mexican border to retrieve them. Seeing our "perfectly good V50" brought to me hoisted on the super-long front forks of a huge front-end loader which dropped the car in front of me, thus allowing me to retrieve the CDs? So sad. Of course, the car powered up just fine and the CDs came out one by one. If you have a water-filled Volvo, prepare for it to be declared a total loss.

 

I understand about the insurance company wanting to total it. They are accepting responsibility that after a given ins covered repair that everything will work, operated and function as designed. If you get in an accident event and one of the airbags does not deploy and more injury occurs, they get into a negligent law suit. The total thing is easier for the insurance company to deal with. I had the insurance adjuster looking at a P1 S40 that the customer ran over a big rock on the road. The front cross member that the control arms bolt too, had the very flat edge bent very little. You could see rock dust on the bent part. The adjuster said replace the front cross member. He said that it is probably OK but if they got into another accident, if another insurance investigation found that bent metal corner from the previous accident, they could sue my insurance company for negligence.
I have dried out too many to remember S40,V50 and C30 soaked carpets. It is not that difficult, just takes time. Watch the YouTube video about unbolting the front seat bolts. Do this for both front seats. I remove the 4 seat bolts only. Pick up the seat and move it to the rear as far as possible. Remove the door sill plate. Grab the door edge of the carpet lift up and out. You have to kind of roll it out to get the inner side to move down some. Using the seat buttons, move the seat down and tilt the seat back forward. Pick up the seat and set it as far forward towards the steering wheel. The below pic it the rear seats. Remove cover 14 and bolts 13. Put the rear seats in the trunk. Remove both outer door sill plates. It is a little harder to remove the rear carpet. It is one piece left to right. Pick up the carpet and pull it down from under the center console. The under side of the carpets are a big sponge. hang the carpets to dry.
A fan helps. It will take 5-7 days for the carpet to dry. Suck up the water in the car with a wet/dry vac. Bolt the driver seat back into place and you can drive the car. Your feet will not touch the floor and not foot rest to press the gas pedal. It will be noisy and hot. You do not realize how much the floor carpet insulates from noise and exhaust pipe heat.
When the carpets are dry spray the carpet underside and floor pan with Odorban, get it at Lowes or HomeDeopt. Odorban will kill germs and dissipate smells. Inspect the AC water drain hose in last pic on passenger side. Pull the lower end of the rubber hose off. Inspect for no dirt blockage ect. There is an exhaust heat shield where this drain hose exits the car. The heat shield will get up against the drain hole and restrict or block up exit water causing it to back up into the AC unit and leak inside the car. With the removed drain tube see if you can push the heat shield away from the drain hole area. After removing all of the carpets, It was not uncommon to have 3-4 inches of water inside the car on the floor pan. There are not any electronics that the water can get too. If you still love the car, you can do this repair.
Besides, you will love your car even more after this repair. If you get stuck on something, just as us. We are all here to help out.