Water leak into boot / wheel well - A4 B8.5 saloon

[F1ux]

Found one issue with my recent purchase 2013 A4.

Water seems to be making its way into the spare wheel well and amplifier bay.

I’ve cleaned all visible drains , and managed to dry out the amplifier bay and think I’ve found the main source of the water ingress which is via the felt liner soaking it up from the inside of the rubber seal. ( see photo).

I’m just not sure how water is getting the wrong side of the seal. Any ideas?

Research suggested removing the plug from the bottom of the boot lid, but that is on the outside of the seal. When removed there wasn’t any sign of water.

when I remove the whole boot seal, the inner that clips on to the boot seems wet

 

[NHN]

Check the boot latch position, adjust slightly to be tighter, also clean up, remove trims & wheel well etc, then with another person one in the boot with torch, other externally spraying a hose, check for leak.

 

[F1ux]

Thanks, checked the boot latched , adjusted and it still leaked.

so next I started pouring water down the side , starting lower down and eventually found the point of failure.

nearer the top it seems water makes its way under the seal, travels down inside it, then exits down the bottom.

I got a piece of a plastic bag and put that between the boot rim and failure point of seal. Poured water and it stayed dry!

so I think I just need to bond the seal to the boot rim with silicone sealant

 

[Booboo]

Put clear silicone sealant on the flange then refit the seal. Factories used to inject mastic in to the base of the dog legs on the boot seals. I know I used to make them

 

[George Crawley]

Not sure if you fixed this issue but I am having problems with water ingress into my boot panel on the left hand side (where you would unscrew the rear lights from). Along with water I've also had small amount of gravel in there which seems to be coming from the vents (Part number 8K0819161C). Apparently the seals can go bad, allowing water back in from the road, and so I've got a parts request in for 2, seeing as the bumper might have to come off I'll replace both at the same time. Might be worth checking these too?

 

[F1ux]

Not sure if you fixed this issue but I am having problems with water ingress into my boot panel on the left hand side (where you would unscrew the rear lights from). Along with water I've also had small amount of gravel in there which seems to be coming from the vents (Part number 8K0819161C). Apparently the seals can go bad, allowing water back in from the road, and so I've got a parts request in for 2, seeing as the bumper might have to come off I'll replace both at the same time. Might be worth checking these too?

yep mine is fine now after bonding the seal to the chassis with silicone!

 

[Thedudeabides22]

I have not got a leak but a full bottle of screen wash has emptied into where the spare wheel is (lid not screwed on right) how did you manage to get the water out from underneath the spare wheel and battery? Is there a “plug” or something? Thanks

 

[NHN]

Just get a biggish towel, soak up & squeeze out, do 10 times or so, easiest option tbh as you don't want to disturb any plugs as they're usually wax sealed or the like.

 

[WaterAlwaysFindsItsWay]

Dear forum members, I have ran into similar problem like described here. Car is Audi A4 B8.5 2014 2.0 TDI (130 kW), no sun roof, not involved in accident.

Problem discovery:

Couple of weeks ago I left my car at Audi dealer for battery replacement. Day after I took over the car I noticed that boot lining on the boot floor is wet. Since the wet spot was close to the left tail light I have opened the boot compartment where I have my AMP and the sponge was also wet. My initial thoughts were that water was spilled in the boot. I have also checked the spare tire compartment and there was no moisture. So I dry this sponge and AMP compartment and while drying I also wiped the wax that Audi puts inside of these compartments because it had some dirt in it (later I read that it is not uncommon to have dirt there due to the cabin pressure vents). Beside the dirt, compartment looks clean, no rust or anything.

Troubleshooting:

Part 1
Although I suspected that water was spilled in the boot, I decided to overflow the rear of the car with the water hose and check for any leaks. After 20 minutes of soaking there was no visible water ingress into the boot or the AMP compartment. After hose test I power washed the car and it was again dry. This led me to conclusion that assumption of spilled water was correct.

Part 2
So I concluded all is OK and I drove the car. Here and there I checked the AMP compartment for moisture. There was no rain for a week. After the first rain from the initial incident I went to check the AMP compartment and again the sponge was wet. Then I did hose test again. Father was soaking the car and I was in the boot for 20 minutes and I could not locate any leaks - nothing! Then I asked father to spray the water under pressure directly to the boot lid side drain (not something you would encounter during driving) and I saw a couple of water drops coming through the cabin pressure vent top side. Conclusion was that the seals on the vent went bad. I have also checked the stoper rubbers and they are dry. Checked the main boot compartment seal and it seems OK but on the left side it is pretty loose (it comes of the lip very easily).

Part 3
Present time, car was on the rain over night and I check the AMP compartment before work, all dry. No visible ingress of water trough the cabin pressure vent, nothing.
It was raining the whole day I was at work so after the work I again check the AMP compartment and seems dry. While I'm looking into the compartment I see that water drops appear after 20-30 seconds after the boot lid was open through the small gap between two panels (marked on attached picture). Could it be that the main seal is loose and some water gets accumulated beneath the seal. While the seal is compressed by the lid its holding the water and when I open the lid, seal expands and accumulated water drains to the side panels and consequentially to the AMP compartment? That would explain the delay of 20 to 30 seconds.

I have never really looked into this AMP compartment until I noticed that boot floor lining was wet so I have no idea how long this is occurring. I also must say that apart from when i picked up car from the service, boot floor lining was never wet again. In parallel I was also checking the passenger side compartment and that one is always dry.
Car was never involved into an accident. The issue is driving me nuts!

Any ideas or comments on what I am facing here?

 

[NHN]

Good friend of mine had the exact same issue & it was due to a rubbish alignment repair of the panels after a rear ender & subsequently the boot seal wasn't in the position it needed to be & even if it's off by very minor mm it can make all the difference.

Try removing the boot seal, squash it closed more by hand or with some grips being careful not to damage the rubber, then with a mallet refit the seal & slowly tap the seal back on or by hand.

You could try putting some cardboard around the seal then close it on this & retest the jetwash scenario to trace the water leak location.

 

[WaterAlwaysFindsItsWay]

Good friend of mine had the exact same issue & it was due to a rubbish alignment repair of the panels after a rear ender & subsequently the boot seal wasn't in the position it needed to be & even if it's off by very minor mm it can make all the difference.

Try removing the boot seal, squash it closed more by hand or with some grips being careful not to damage the rubber, then with a mallet refit the seal & slowly tap the seal back on or by hand.

You could try putting some cardboard around the seal then close it on this & retest the jetwash scenario to trace the water leak location.

Thanks for the answer!
I would never thought that seal position is so sensitive. Since it is loose at this area it could be the cause but its somehow issue when the boot lid is opened/closed when the water is accumulated (when the seal is disturbed). If it stays closed during the rain and some time after rain stops there is no leak.
I anyway plan to replace the seal and the cabin pressure vent for the weekend.

 

[NHN]

Don't replace anything yet until you've properly found where the issue is as my friend replaced the seal & it didn't help that much.

Do as suggested & see if the issue stops or the cardboard shows a wet patch.

 

[WaterAlwaysFindsItsWay]

Don't replace anything yet until you've properly found where the issue is as my friend replaced the seal & it didn't help that much.

Do as suggested & see if the issue stops or the cardboard shows a wet patch.

What was the solution for your friend then?

 

[NHN]

Due to the absolute steroid infused Bodyshop guy just being a useless idiot, my friend decided to add some extra seal in a location to help push down more to alleviate any small added space between 2 areas so it created a tighter seal so to speak, he also added some sealant inside the boot rubber seal g refitted so it made this water tight also, but be careful not to use anything that couldn't be removed later as using something like sikaflex means it may not ever come of lol.

Otherwise it would have to go back into a decent bodyshop, boot stripped & all aligned properly to fix the issue which was a huge expense.

Unfortunately my friend didn't know the bodyshop would do a rubbish job, also when testing this issue, when he put some tape on the paintwork to hold something in place, the tape stripped the paint of, which is due to very bad base prep, so another issue, which says allot about why he had the leak in the 1st place, just rubbish workmanship.

 

[WaterAlwaysFindsItsWay]

Well I am not the best example DIY guy on the car so I would prefer not to fiddle around with the seal and additional sealants inside.
I anyway have to take the car to the shop because, in addition to this, last time when I was detailing it I discovered some rust spot above the tail light on the trunk. I could not believe this, later I read on forum that it is fairly common spot on this model to develop rust.

 

[NHN]

Is that from where the light has been removed & refitted & rubbed against the panel causing the issue later on?

 

[WaterAlwaysFindsItsWay]

Is that from where the light has been removed & refitted & rubbed against the panel causing the issue later on?

Light was never removed. Gap is also sufficient between the light and the panel. Also, no misalignment visible.
On the passenger side it will also start to develop corrosion it seems. I can see the small crack in the paint. It seems this is coming from the inside out.

 

[NHN]

Has it had a little shunt or any work you're not aware of as you've got water leaks & cracked paint, those points youve shown are stress points if the rear has been hit & of course possible reason for cracked paint, who knows.

 

[WaterAlwaysFindsItsWay]

No shunts, no accidents and no bodywork or any kind of repairs done.
Apparently condensation gathers up at these spots inside of the trunk causing this event. In some cases Audi covers the repair expenses (or even a new boot lid if the damage is to great to repair).

 

[NHN]

Yeah I guess if that's the case, then I'd hazard a guess the moisture is causing the panel joints to separate & split the paint, that's a sign of either bad bonding material or the wrong choice in how they join.

Another great bit of QC by Audi.