Water Leak - E36 Coupe

[wrs 120]

I've been chasing water leaks for the last few weeks. I've identified all but one of the sources. The last leak has me a bit baffled though so hopefully someone here will know this one. It's in the front left corner of the passenger footwell up against the firewall.

The photo below shows where the water reveals itself for the first time. The yellow circle encloses the wet area where the water comes out. The water appears to be coming out from behind the black sound padding and runs down the cable loom marked, goes behind the plastic shield and ends up on the floor. The small ledge where the sound padding finishes is also wet. Is this similar to the A-Pillar leak I've seen mentioned on many sites or something else?

The water has been coming in over the last few days while it's been raining. I've tried to get water to enter by running the hose on the sunroof, down the windscreen and onto the shield below the windscreen but cannot get the leak to show. It doesn't appear to be leaking through the door or door seal.

I have to take the dashboard out soon to replace the heater and want to install new carpet at the same time but have to have all the leaks fixed prior.

Any ideas where to look?

Edited October 9, 2017 by wrs

[dirtydoogle 383]

I have a few e36s with no interior and no motors if you wan to come have a look for leak points, am in Hastings 

[wrs 120]

Nice!!

I think that would be worthwhile.

When you say no interior do you mean completely stripped as in no dashboard too? At the very least it would show where the water can track from-to...

Edited October 9, 2017 by wrs

[aja540i 1906]

Have you checked the little compartment where the ecu lives? It is accessible from the engine bay and I believe if the drains get blocked the water can track back down the wiring loom into the car.

[wrs 120]

Thanks, haven't checked this yet. I have a Link G4+ in this compartment and definately don't want water getting into it. I'll be checking this tonight for sure...

Some years ago I did get water in this compartment due to the drain in the heater area getting blocked and water would flow into the ECU compartment when going round a corner. It fried one of the coil driver smart transistors and I thought I'd need a new ECU. However, the local BMW shop showed me to a box of old blown ECU's so I robbed a transistor to replace into mine. Got it going again using the robbed part. I thought I'd solved the water problem by gluing in a baffle to stop water ever getting in there again. Worth checking it's still working + to see if water is somehow getting back in now...

[wrs 120]

Found it - nasty little bugger too...

It's coming from the big plastic bung where the fusebox pokes through the firewall. You can see a drip forming. It's seeping in from all round the perimeter as well as where the cable comes through.

Water goes down this gap in the metal round the engine bay and drops directly onto the electrical fusebox area.

Since this is going to be near impossible to seal round the fusebox/firewall the only option is to stop the water getting into the engine bay. Why this gap is there beats me... I'll fill is with poos to seal off the engine bay and hopefully that's the end of the problem.

[wrs 120]

1 hour ago, aja540i said:

Have you checked the little compartment where the ecu lives? It is accessible from the engine bay and I believe if the drains get blocked the water can track back down the wiring loom into the car.

Checked this too - dry as, so my original mod still appears to be working well.

Was just about to seal up the gap and it started chucking it down again...

[Mad_Max 231]

21 hours ago, wrs said:

I have to take the dashboard out soon to replace the heater

Just on a side note, if you're changing the heater core, the dashboard doesn't need to come out to do this, everything comes out the passenger side. Don't believe what the American websites say when they claim it's a day's work to get one out, I removed, flushed and refitted the one in my E36 coupe in about 3 1/2 hours. 

[wrs 120]

Thanks, but the dash is coming out so I can change the sealing frame between the heater body and the firewall - it's leaking. I'm also doing an electric conversion to get rid of the risk of the heater core splitting sometime in the future.

I'm 3/4 of the way there anyway since I had to strip everything to find the leaks. Had 4 in total - between the heater and firewall, from the heater core, from the fusebox/firewall and from popped bungs in the floor. 3 out of 4 are now fixed with the last one (heater/firewall) getting fixed when Ireplacing the heater with the second hand one converted to electric.

The only leaks I didn't have were two of the most common ones - A-Pillar from the sunroof and door seal...

[wrs 120]

Here's the original 'Sealing Frame' gasket from between the heater box and firewall. This was the bottom left corner which happens to be where the leak was. It's pretty clear the seal has either failed or was never installed correctly from the factory.

On the new install the seal has been checked and the sealing foam can be seen bulging out from the inside and from the engine bay so it looks like it has a good seal this time. Another give-away was when the old heater was removed it didn't take much of a push to get it free. On the donor heater I got from the wreckers a jimmy-bar was needed to pry it loose - it was stuck pretty good.

[Michael. 2313]

Nearly every e36 I've touched has water leak problems, passenger side. 

Certainly a design problem + age/enviromment that causes it.