Horrible trunk leaks

[garciapiano]

Hi all,

I have been experiencing some leakage of water into my trunk. The right hand side of the trunk is wet and I believe it is coming from two different areas. One is the right hand tail light housing, which I will be sealing back up with closed cell foam tape. The other is the rear fender wells which are both missing a round body plug of some sort. Does anyone know the part number of the plug?

 

[dzl_nator]

I once had water enter the trunk from behind the little trim plate at the bottom of the C pillar.

 

[Mongler98]

pull all the carpet out of the trunk area including the side areas around the wheels. i bet you $10 you have a fairly large area of rust around the wheel well on the passenger side where the filler neck is. VERY COMMON area to rust out with no idea of whats going on. I have the same problem, after trying to chase leaks on tail lights and what not, turns out i have a massive spot of rust the size of a dinner plate in that area.

Do you have any rust in the gas fill area at all??

 

[garciapiano]

pull all the carpet out of the trunk area including the side areas around the wheels. i bet you $10 you have a fairly large area of rust around the wheel well on the passenger side where the filler neck is. VERY COMMON area to rust out with no idea of whats going on. I have the same problem, after trying to chase leaks on tail lights and what not, turns out i have a massive spot of rust the size of a dinner plate in that area.

Do you have any rust in the gas fill area at all??

No rust, but the paint and seam sealer does show some hairline cracks in the filler area. I’m fairly certain that rust is not an issue as this is a California car and there is hardly rust anywhere on the car or in the trunk area.

 

[Mongler98]

No rust, but the paint and seam sealer does show some hairline cracks in the filler area. I’m fairly certain that rust is not an issue as this is a California car and there is hardly rust anywhere on the car or in the trunk area.

only reason is because the neck traps dirt and keeps moisture around and it rusts out.

 

[turbodieseldyke]

Does the water appear after driving in the rain, or sitting?

If nobody sells those rubber body plugs anymore, maybe you can silicone the whole thing up.

 

[ToddA1]

I’ve bought rubber plugs up to 2” diameter. Search rubber blanking grommets.

Otherwise do it the way VW used to do it... tape with seam sealer brushed over it. Personally, if you don’t care about the aesthetics, Gorilla tape will seal it. That stuff is tenacious.

-Todd

 

[Mongler98]

I’ve bought rubber plugs up to 2” diameter. Search rubber blanking grommets.

Otherwise do it the way VW used to do it... tape with seam sealer brushed over it. Personally, if you don’t care about the aesthetics, Gorilla tape will seal it. That stuff is tenacious.

-Todd

on that note, look up HVAC mastic sealer, designed for HVAC duct

the real trick here is to seal it up with NO rust present otherwise you will make it 100x worse in a few years, thats actually the main reason im scrapping my MK3

 

[thechoochlyman]

Seems like a good thread to bump. I've been dealing with horrible trunk leaks of my own, but think I have it narrowed down to the lid seal itself. Here's a link to the part on VW's parts website, but unfortunately it's NLA.

Both of my plastic storage cups on the sides are always full of water, and sometimes there's water on the side carpet too.







There was nothing keeping the strip attached at the upper edges, and I can see water all underneath it.



I've put a good bead of weatherstrip adhesive around it on those areas and hopefully it'll help. The worst part is that my plywood floor is now moldy.

 

[ZippyNH]

Have you adjusted the rubber bumpers on the trunk to make up for wear if the rubber weather stripping? Good first thing to try...
They rotate to make them taller or shorter

 

[garciapiano]

Are you 100% sure your trunk lid seal is the issue? The only way I could see that happening is the water somehow traveling under the seal through capillary action.

In my case, the trunk leaks were completely fixed by renewing the tail light-to-body seals with some closed cell whether stripping tape. I did get lucky though. The leak source was completely invisible otherwise, in any case.

 

[thechoochlyman]

Are you 100% sure your trunk lid seal is the issue? The only way I could see that happening is the water somehow traveling under the seal through capillary action.

Honestly, that's exactly what I think is happening. Immediately after it rained I took a look, and water was dripping from the top edge onto the trunk springs. It was moist under the seal too, but only in that middle area. Bad tail light seals could explain some of the water in the bottom of the trunk, but not the water that's all over the sides of the carpet.

Have you adjusted the rubber bumpers on the trunk to make up for wear if the rubber weather stripping? Good first thing to try...
They rotate to make them taller or shorter

I haven't, but I'll try that too!

 

[thechoochlyman]

Probably no surprise to you guys, but my leak persists. lol It rained a lot last night and once again the trunk is really wet. I took your advice and pulled out the tail lights, sure enough it was pretty wet back there. I ended up swapping both of them with spares - one had a broken stud and the other had a chip at the top and was full of water.



I cleaned the mating surfaces up really well and applied a bead of yellow weatherstrip sealer. Hopefully this will make a difference.

 

[thechoochlyman]

Well it was still leaking after I did the tail lights. So I moved on to the weatherstrip seal after seeing wetness on top of it.



I threw on a used one from a parts car and inserted 3/8 vinyl tubing to make it taller. Even still, it leaked.



I noticed it was wet inside the trunk near the pinch welds.



So I dug out all that old stuff and filled it in with something new. Hasn't rained again yet, but fingers crossed.

 

[alanack]

Theres a reason my B4V stays in the garage