Sealing plugs in undercarriage

[Dino D]

So after removing the carpet I have traced the cause of water in the interior to a damaged drain plug in the undercarriage under the drivers seat.
From the inside of the car the is a butyl seal pad stuck over the area and the plug has been pushed upwards a bit making a small gap to let water in from the road when moving.

I am thinking to get some more butyl pads (like what is used for flashing) and stick that over and later on reseal the underside at a Bodyshop that does this sort of thing.

Anyone done this or can share experience or opinions?

[Vic-Z3]

If you can push it down from top, then reseal with a bitumen based paint.
Done this on mine.

[beerbelly]

push it back into the hole then seal with pu sealant from underneath. but its very likely that its been pushed up from underneath by a previous owner to let out water that's coming from above somewhere

[Jonco]

........... but its very likely that its been pushed up from underneath by a previous owner to let out water that's coming from above somewhere

Agreed - had to that with mine to drain a `mysterious pool' I found when doing seat bushes and then reseal it.

[Dino D]

I think I'll do the up sealant and then lots of butyl sheets over.

The plug has been damaged not purposely removed (slight sent in the floor, not jacked up car yet) but is likely from when I went over a speed bump outside my house (I hadn't used the car in months and normally straddle the square humps we have but in the Z I must go in the middle of the road with the wheels going over each hump, simply forgot and scraped the bump).
I do want to get it on a ramp an check over everything one of these days and give it a an underseal as the dealer must be scrathed too.
It's not been driven this winter so minimal water ingress and check the carpets periodically anyway (being a convertible owner in hhis country means a degree of paranioa for leaks!!)

The only other leak I have is into the boot and that has been traced to the butyl seal so needs a new top at some point. Nothing major and now that I don't use her daily she is under a car cover when it rains.

[Vic-Z3]

The only other leak I have is into the boot and that has been traced to the butyl seal so needs a new top at some point. Nothing major and now that I don't use her daily she is under a car cover when it rains.

I had this and used "CAPTAIN TOLLEY CREEPING CRACK CURE" found on ebay........................ Bloody marvellous ...........

Undo the hood and prop it up with a suitable piece of wood, so the rear is all saggy. Then run some of the above starting from the middle around the rear, where the
body meets the hood.
I have no more leaks into the boot or the cabin in over a year of some off the worst rain we have ever had.

[Dino D]

Just googled that half worrying it was a prank with that name!!
At under £10 it's work a go. Thanks for the tip!

[Vic-Z3]

Best under £10 quid I invested in .................

[Dino D]

I splashed out and ordered the 25l bottle at over 10 quid with delivery!
Going to try it headlight/tailight seals as they get tiny amounts of moisture in sometimes as well do the 3rd brake light and ariel grommet which are common leaky spots.

[Dino D]

The only other leak I have is into the boot and that has been traced to the butyl seal so needs a new top at some point. Nothing major and now that I don't use her daily she is under a car cover when it rains.

I had this and used "CAPTAIN TOLLEY CREEPING CRACK CURE" found on ebay........................ Bloody marvellous ...........

Undo the hood and prop it up with a suitable piece of wood, so the rear is all saggy. Then run some of the above starting from the middle around the rear, where the
body meets the hood.
I have no more leaks into the boot or the cabin in over a year of some off the worst rain we have ever had.

Just to update and say thank for the advice.
I've tried the sealer on the goo seal and have applied it a number of times now over a few weeks and the leak into the boot is much less. I think. A few more applications and I could be leak free...

Probably worth making this a sticky or adding to knowledge base?

[henrycrun]

BTW what colour is Captain Tolley's Crack ?

is it runny enough to wick all around the 3rd brake light ?

[Dino D]

It's clear when dry, milky white when wet.
Very runny, almost like water (it is water based).
Wipes off easily enough though if you get some on the bodywork.

[henrycrun]

OK - how does one separate the 3rd brake light lens from its black base ?

[Dino D]

Never done it myself.
With the creeping crack cure you don't have to split apart the items if the gap to be sealed is very small. If you are going to split it then you can use silicone or get a new gasket from BMW which I believe is cheap.
I think there are some detailed posts in the knowledge base on here about this.