Honda Civic 1998 Leaking Into Passenger Footwell.?

Question

I have a water leak coming into the passenger footwell of my Honda Civic. Its from rainfall, as it happens when the car is standing.

When I peel back the carpet on the passenger side, I can see a black rubber type mat that goes from the floor up towards the engine. This rubber mat has a fabric type bottom. The water is coming in under this rubber mat and collecting on the passenger floor.

I stuffed some newspaper under this rubber mat to soak up the water. When I removed the newspaper it was mostly wet on the left hand side (bodywork side).

I tried sealing round the bottom of the windscreen on the passenger side with silicon sealant but this has made no improvement.

I left it into a mechanic on Monday and he sealed bulkheads - its still leaking this morning.

Any ideas how best to trace the leak. I was unable to remove the black rubber mat going up into the engine to get a good look at the source of the water

I hope I'm adding this addition in the right place.

I don't think it is the heater core as that would suggest water leaking from the closed heater water system. The radiator level has not dropped and there is no discoloration in the water from the antifreeze.

Similarly, there is no water leaking from the window washers.

This problem only occurs when it rains.

I am in the UK - hence I refer to the bodywork being on the left of the passenger side.

I don't believe it is leaking from the door seals as the water is coming from under the black rubber mat that runs up towards the engine. This mat is at the most forward point of the footwell.

A quick recap.
The leak is definitely being caused buy falling rainwater. If I dry the water up then none reappears until it rains again. The water is coming from under the black rubber mat/shield that is under the carpet in the passenger side. This runs up into the engine but I don't know how to remove this mat to go any further towards tracing the leak.
As the leak is rainwater there are a limited number of places where it could enter the car. I have been advised outside of Y.A that it could be via the sunroof seal, the windscreen seal, cracks in the bodywork, through the ventilation system and so on.
I'm going to attempt to narrow it down by using food-colouring in water and pouring the water onto specific areas that could be at fault. I need to wait until I get a few dry days before I can try it properly.

Answer 1

I'm surprised your mechanic did not say anything about the heater core, because as you see some of us agree in here that the heater core is probably at fault... I am guessing you live in England maybe? ( I was confused at first, because the body side of my car is on the right side of the passenger side....lol). I'm thinking the winter snow and the salts on the roads take a toll on the bottom of the car causing rust at the floor boards.

Answer 2

Oh my goodness. For years I drove a 1988 Acura (it's basically a Honda) - and just last year I had the same exact problem. I never even thought to ask the mechanic about it because I thought that somehow the water was coming from outside - and just like you - it only happened when it rained. (I'm in northern california. It only rains here in the winter)

At the same time - I DID have problems with my cooling system. The car would register as running hot - but there was never any steam or anything. Because the car was 20 years old - I didn't even bother with it for a long time. I thought the gauge was goofy. But - when I did take it into the shop - my mechanic said it was something to do with the radiator - and that it was losing water. (I'm sorry - I can't remember exactly what part he replaced). I never thought anything about the two problems being related to each other. Still - like you - there was no smell of anti-freeze in the car - and you'd think that would happen.

My Acura died last year so there was never a resolve regarding the water on the passengers side. If you get a definite answer on this - would you let me know? I've always wondered. Plus I'm driving a 1990 Civic now - and maybe this is a Honda thing. Great cars though!!!

Answer 3

Check the rubber door seals on the passenger side. They are located on the actual doorway rather than the door. The water can leak through them and then run along and down into the footwell.

Another cause of a wet footwell is a burst heater matrix.

The very best of luck

Geordie

Answer 4

Hello, i have exactly the same problem with my civic 98. I saw it 3 months ago and i left it with Honda Service and they changed something in radiator. They said it's all right but after some days when it rained again i saw water in the passenger's floor. This week i will go the car in bodyshop. Did you manage to find out anything about your problem?? Many people write about the same problem but none of them seems to find a solution. If you know something more please answer to me. Thank you in advance, Lena from Aberdeen, Scotland.

Answer 5

Try drying it up as much as you can then shutting yourself in the car & get someone to play a powerful hose over it from the outside, including underneath. With luck you should see where it's coming in, otherwise you're guessing.

It's unlikely to be the heater, as you'd smell the coolant.

Answer 6

there are a number of different reasons why it would leak, the windshield is a possibility. but if you take the cowl off (the black plastic thing underneath the windshield wipers) you may beable to find a crack in a seam someplace. if it only does it when it rains, thats probably where its going to be. a good body shop should be able to find where its coming from.

Answer 7

Probably the heater core, but try taking the car through a car wash.

Answer 8

Most cars that leak under those conditions are leaking from the windsheild and the windsheild must be removed and resealed, resealing from the out side will not solve the leak

Answer 9

If water came out the heater behind the glove box, sounds like you need the heater checking by a mechanic. or maybe theres a hole under the car

Answer 10

it mite be the heater coil, check the radiator level for loss of fluid.
if it low then it mite be it.