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Topic: Unlucky for some 13 potential water leak areas. (Read 3461 times) previous topic - next topic

Unlucky for some 13 potential water leak areas.

(thanks to eddypeck)

There's a whole bunch of common places where water can get in, most Mk2 owners will be able to tick off at least a handful of these at one time or another. This isn't supposed to be a guide on how to solve each problem. It’s just to give you a start on where to look. There's plenty of info on fixing each of these on the forum. Please feel free to add more as you find them. I'm sure there's plenty.

1. Sunroof seal, often thought to be the main culprit but this is not 100% watertight anyway. However if it's totally gone, in heavy rain more water gets past it than the drain tubes can cope with and let water into the car, potentially damaging the headlining.

2. Sunroof drain tubes, this is the main culprit of water from above. There’s one in each corner and they get blocked and need to be cleared so water can run away freely. Check the spouts or sunroof gutters haven’t rotted away also. Combined with a new seal your roof will be leak free.

3. Inner wing drain holes, these get blocked with leaves etc so water collects in the scuttle and backs up into the car through various points…

4. Blower motor fresh air intake, see item 3. Remove grill, clean and reseal in conjunction with doing the above.

5.  Bonnet release cable grommet, in the scuttle, see item 3.

6. Scuttle panel/bottom of windscreen, these rot. Any sign of rust creeping out from under the windscreen seal it’s worth taking the screen out to check it out.

7. As above, but without removing the screen you can sometime see by just removing the dash speaker grills to see the corners. Or remove the dash to check the full length of the scuttle.

8. Heater matrix, water in the footwell may not be rain water. Check it for coolant it could be a leaking heater matrix

9. Door membranes and window scrapers, as with the sunroof seal water gets past the scrapers. There are drains in the bottom of the door, make sure they’re clear. Damaged or missing membrane will ruin the door cards and let water into the car. Yacht Varnish the back of your door cards for added protection and strength. 

10. Door seals – if water still gets with the above addressed it could be door seals, or door fitment. The doors can drop and not shut properly leaving gaps for water to get in.

11. Rear light seals, the rubber around the rear lights can let water into the boot.

12. GTI spoiler screws, there should be rubber seats for the fixings, if these are perished or missing water can get in.

13. General rot; A-pillars, inner wings, rear turrets, floor pan, bulk head …. There are quite a few common rust areas that are potential areas where water can get in.
National Meet - 18-20 July 2025 @ Curborough Sprint Course

Re: Unlucky for some 13 potential water leak areas.

Reply #1 –
Thanks to James827 for this:

14. leak in the rear boot? check the boot lock seal and all the screws and plastic things that hold in the plinth and number plate lights are there! one plastic screw guide missing can cause an annoying leak, also check the bottom of the rear screen and all along the sides on the inside of the boot-lid, it can be overlooked and could well be rotted out.

Check around the rear wiper, squirter, bottom of screen for rust especially on a GTI where it can be hidden under the sticker but water can still get through.

Also if you're rear washer doesn't work don't just presume it's a blocked jet or faulty pump. You could well have a break in the pipework and every time you try it you could be pumping water into your car....
National Meet - 18-20 July 2025 @ Curborough Sprint Course

Re: Unlucky for some 13 potential water leak areas.

Reply #2 –
Thanks to Wingchundub
15. Wiper grommets especially on earlier type 19 due to wiper being on passenger side.
Water was coming in and I assumed the scuttle with splits.
Fixed them and spotted water coming in via grommet which then drops onto linkage arm directly above blower and can see water trails in fan housing.
Silicon applied and she has been dry ever since
National Meet - 18-20 July 2025 @ Curborough Sprint Course

Re: Unlucky for some 13 potential water leak areas.

Reply #3 –
Even though I wrote the guide, I managed to get a puzzling water leak in my latest Mk2 which wasn't any of the above.

I had signs of it early on with a drip above the fusebox. Sealing the bonnet release grommet (#5) didn't solve it.

Further investigation, which was back-ed up with a tip of from a fellow Mk2 owner had me suspecting the blank panel under the ECU.
For LHD cars this is a big whole the same as we have on the other side, where the blower vent is.

Turns out the panel is sealed with a bead of wax and a sheet of bitumen over the top. Both prone to going brittle with age.

With dash removed, fusebox dropped and the fusebox cradle taken out you can see the pink blank panel:


From the top side, with ECU, ECU bracket and the panel removed:


Cleaned up, rust treated, seam sealant and painted:


Fingers crossed and good luck to anyone suffering with the same.

Re: Unlucky for some 13 potential water leak areas.

Reply #5 –
Quote from: Eddypeck on
Even though I wrote the guide, I managed to get a puzzling water leak in my latest Mk2 which wasn't any of the above.

I had signs of it early on with a drip above the fusebox. Sealing the bonnet release grommet (#5) didn't solve it.

Further investigation, which was back-ed up with a tip of from a fellow Mk2 owner had me suspecting the blank panel under the ECU.
For LHD cars this is a big whole the same as we have on the other side, where the blower vent is.

Turns out the panel is sealed with a bead of wax and a sheet of bitumen over the top. Both prone to going brittle with age.

With dash removed, fusebox dropped and the fusebox cradle taken out you can see the pink blank panel:


From the top side, with ECU, ECU bracket and the panel removed:


Cleaned up, rust treated, seam sealant and painted:


Fingers crossed and good luck to anyone suffering with the same.

Yeah, I think it's safe to say that's not going to leak now! Haha

I'm going to check mine tomorrow. Thankfully mine is ok so far

Re: Unlucky for some 13 potential water leak areas.

Reply #6 –
@Eddypeck - did sealing up the ECU cover 100% solve your leak? I seem to have a leak from the area circled in yellow, but can't see how water is getting in from that location? is that even possible? I ask because my ECU appears to be pretty dry aside from some condensation...

Re: Unlucky for some 13 potential water leak areas.

Reply #7 –
Quote from: samurl on
@Eddypeck - did sealing up the ECU cover 100% solve your leak? I seem to have a leak from the area circled in yellow, but can't see how water is getting in from that location? is that even possible? I ask because my ECU appears to be pretty dry aside from some condensation...



Unfortunately not.
I had the windscreen replaced and after that it seemed to stop, else I didn't notice it for a while.
But the leak is back so I don't know if it's the windscreen seal or if that's a red herring.
I can't work out where it's coming from a have resigned to the fact I now need to keep the car under a cover.

Re: Unlucky for some 13 potential water leak areas.

Reply #8 –
@Eddypeck - I could imagine we are sharing the same issue. I am tempted to pump a small amount of silicone up into the gap to see if that fully solves the leak, and then at least I know where it is coming from. I feel like I have the exact same issue on the passenger side.

Re: Unlucky for some 13 potential water leak areas.

Reply #9 –
Quote from: samurl on
@Eddypeck - I could imagine we are sharing the same issue. I am tempted to pump a small amount of silicone up into the gap to see if that fully solves the leak, and then at least I know where it is coming from. I feel like I have the exact same issue on the passenger side.

I've actually just done a test, I emptied a couple of litres of water into the scuttle and nothing came through. So I think the issue must be further up. Since I've had the screen out and know the top of the scuttle is OK I fear it could be the bottom of the A pillar. I know they can rust there.

I've found a pic that shows the area:



I hope it's not the case but I fear it's the only thing left to check, and the only logical answer.

The pic came form here, and there's some other pics and more info about this area.

Re: Unlucky for some 13 potential water leak areas.

Reply #10 –
@Eddypeck - yes I fear exactly the same...

The v odd thing for me, is that it appears to have happened very suddenly... the car went from dry to wet inside what feels like almost overnight...

Just to share with you... I ran a bead of silicone across the join line and also pumped a small amount into the gap (the one in the circle above) but it hasn't prevented the water from coming in...

Obviously the weather is pretty hopeless so feel like I'm going to have to run with it until spring/early summer and then strip it down further...


Re: Unlucky for some 13 potential water leak areas.

Reply #11 –
Quote from: Eddypeck on
Quote from: samurl on
@Eddypeck - did sealing up the ECU cover 100% solve your leak? I seem to have a leak from the area circled in yellow, but can't see how water is getting in from that location? is that even possible? I ask because my ECU appears to be pretty dry aside from some condensation...



Unfortunately not.
I had the windscreen replaced and after that it seemed to stop, else I didn't notice it for a while.
But the leak is back so I don't know if it's the windscreen seal or if that's a red herring.
I can't work out where it's coming from a have resigned to the fact I now need to keep the car under a cover.

I have exact same issue. As above I tried filling it with some silicone but water still drips from in-between the crease!

Any ideas where it's getting in from?

Thanks
 

Re: Unlucky for some 13 potential water leak areas.

Reply #12 –
See above. I can only assume it's coming in from the bottom of the A-pillar. I'm reluctant to take my wings off to check, but that might be the only way I'm going to find out. I already took my windscreen out already and can confirm the scuttle is all good.