Water entering E30 - help me locate the leak

[oelholme30]

Hello R3V

I'm the happy owner of a euro 1987 325I facelift 2-door.

About a month and a half ago I went for a drive, and I noticed the carpet was absolutely soaked. I pulled the interior and found water entering the interior from what seems to be the firewall and dripping down to the gas pedal area.

I've been searching for the entry-point for a good while now, but I can't seem to find the exact point of water entering.

Things I've checked:

• The elephant trunk: replaced about two years ago, clean as a whistle
• The cowl drains by the fender: runs out just fine.

Things I've noticed, however:

• Theres still water in the cowl after most of it has drained out. About an 8th of an inch just kind of sitting there.
• Theres a teeny tiny split between the two skins under bonnet gasket, however it's a tiny bit of separation. Should I put some sealant on it?
• Theres a small rust hole to the right of the engine-loom grommet on the firewall, however it's completely dry to the touch - water isn't coming through it.
• There's a bit of crumbling to the left of the loom grommet and a bit higher up looking at it from the interior. It feels wet, but it doesn't seem to be where water is entering.

I've tried to move the fuse box slightly, but the loom is very tight and I can't pull it away. I've also tried spraying water all over the front of the car, and it isn't pissing in. Just a slight drop down the firewall now and then - but it accumulates.I'm unsure what part is leaking in. When I poured a lot of water into the cowl it seemed waterproof, but the day after the floor was soaked again, making me suspect that there's a slow leak from there - but I'm not sure.

It could also be the windshield gasket, but I'm not sure how to test it, as spraying water on it will also get it everywhere else.

I should add that previous owner has applied noise dampening to the floors with a thick rubber skin, so I don't think the water has damaged the floors of the car.

I don't know if it's related, but I've also always found water along the sides of the engine bay when it rains.

PS: New user - I hope I posted the right place!

[tomstin]

There are three drains for the HVAC box. Remove the console, there is one behind the ashtray area, and one on either side of the transmission hump a few inches toward the firewall. The rubber hoses deteriorate over time. With the carpet installed they can be difficult to see and fiddly to replace.

[oelholme30]

There are three drains for the HVAC box. Remove the console, there is one behind the ashtray area, and one on either side of the transmission hump a few inches toward the firewall. The rubber hoses deteriorate over time. With the carpet installed they can be difficult to see and fiddly to replace.

I will have a look. I don't have air conditioning and the car haven't run in about two months - will that effect anything?

[tomstin]

Rainwater will enter in through the center cowl vent. Same place where the air comes in when you turn on the fan.

Also, do you have a sunroof? When those drains clog at the rocker, you can get water into the floorboards.

[oelholme30]

Rainwater will enter in through the center cowl vent. Same place where the air comes in when you turn on the fan.

Also, do you have a sunroof? When those drains clog at the rocker, you can get water into the floorboards.

definitely not sunroof vents, water comes down the firewall.

I'm guessing as a lot of water remains in cowl after done draining that this is the culprit

[oelholme30]

Rainwater will enter in through the center cowl vent. Same place where the air comes in when you turn on the fan.

Also, do you have a sunroof? When those drains clog at the rocker, you can get water into the floorboards.

definitely not sunroof vents, water comes down the firewall.

I'm guessing as a lot of water remains in cowl after done draining that this is the culprit

[brutus]

ther is a black plastic pipe, called ( the elephant trunk) which lets water drip out from the firewall, next to the inner side of the battery tray,,,check its not blocked !

[oelholme30]

I think I've gotten closer to finding the leak.

Yesterday I was looking into the cowl through the hole in the fender, and I noticed there was a lump of something blocking water from draining fully, perfectly corresponding to the height of water visible after draining when looking through the cowl vent.

I tried chiselling it with a hammer and a flathead, and I got most of it out however not all, as I am afraid to damage the paint and metal of the cowl.

I have no idea what material it is. I tried heating a bit I extracted with a lighter and it began burning violently. Hoping to try using some vinegar to see if it dissolves it.

[oelholme30]

Here is the drain after chiselling + the level of water that won't drain when looking into the cowl vents.

[oelholme30]

And here is where water enters cabin - by the three prong bracket under the dash, that I don't know what does.

[BadDays]

Sometimes, Insulation or protective material can clump up and cause issues where you don't suspect it, That actually looks like a mix of insulation and mud so I'd start getting as much out as you can. Pour water over the vents and make sure you got most of it out to verify that you did unclog the mess. This might be a bigger job than you expect!

[oelholme30]

Sometimes, Insulation or protective material can clump up and cause issues where you don't suspect it, That actually looks like a mix of insulation and mud so I'd start getting as much out as you can. Pour water over the vents and make sure you got most of it out to verify that you did unclog the mess. This might be a bigger job than you expect!

Fairly sure it was previous owner who tried to seal the drain from draining into the wheel well. I got a big chunk of it out today, and it seems like building foam almost.

The issue I found now is that it needs to be removed almost 100% as the drain incline is super small. I had to chisel with a hammer and a flathead, and as im getting close to actual metal im afraid of punching a hole or denting it. I need to find a clever way to maybe desolve it. I tried putting a chunk I hammered out in vinegar and it doesnt seem to effect it.