Water in Passenger Footwell - still!

[Bumpa]

I am determined to fix the wet footwell on my 1977 1850HL. If you look at my photo you will see that the water appears at the joint where the vertical panel meets the floor, tracks along the top of the anti-drumming surface, then spills over to form a puddle as indicated.

There is no corrosion in the bulkhead area and all welded joints look fine, but the water must get in somehow. Has anyone had a similar problem and how can it be fixed? I hate a car with wet floors.

Mike

[new to this]

Have you checked the windscreen seal,get some one to spray a hose or watering can over windscreen,you lay down in the footwell,but as your laying there dont go to sleep

Dave

[GrahamFountain]

I still haven't got the Doly windscreen seal watertight yet. I know there's a leak above the mirror - it runs down the inside of the screen driving into the rain.

I think the two little puddles that form on the outer bottom corners of the windscreen when it's stood are part of the problem. On the Herald, I've filled the trough above the seal with black silicone rubber, made to slope slightly away from the glass. It ain't pretty, but it seems to have gone a long way to fixing the swimming pools in its footwells.

Graham

[Bumpa]

After much work I am sure that the water does not come from above. Today I have stripped off some of the sound deadening from the engine side of the bulkhead and I directed a thin jet of water from within the engine bay directly onto the bulkhead, and the familiar beads of water appeared inside as per my photo. I am convinced (almost) that it penetrates the seam between the vertical bulkhead and the floor. I'm going to slap some sealer over this area under the bonnet and see what happens.

[MIG Wielder]

When I had an identical problem I found the two most useful bits of diagnostics were...
Take the glove box out and look behind it with a bright torch.
Stretch some cling film over the heater air-box intake .
On this test you can remove it 1/3 at a time to check for water ingress.
In my case the main leak was the windscreen seal but there was also one from the wiper spindle. A new seal didn't cure it so I filled the orifice with silicone sealant and then added thick grease to the wiper spindle.
As you note though I agree that the source of your leak is lower down.

Tony.

[dollyman]

Have you tried talcum powder Mike? It has never let me down when tracing leaks

Tony.

[Richard the old one]

I have a similar problem in one of my cars and I have found that if i place some polythene over the air plenum chamber and then shut the bonnet this stops any rain getting into the plenum chamber and no water finds its way into the foot well. If I pour water into the plenum chamber it does drain away but I have not as yet found how some ends up in the foot well because it obviously runs down behind the sound deadening.

I did this in part to proved that my windscreen was not leaking.

The following photo shows how the water drains down behind the sound proofing on the off side.

[Bumpa]

That's it Richard. The arrow on the right of your picture deposits the water on top of the joint between the bulkhead and the floor and the inner wing, and that's where I think the water somehow seeps through that joint. The design allows a small amount to collect there. I slapped a load of sealant on that seam last night and must use the hose to see if I have have stopped it. But although it's sunny here this morning, it's a tad chilly at the moment!

Rain water ingress seems one of the hardest things to eliminate on many types of car. I had an early MGF which let water through body seams, as did my BMW Z3, so what chance have older cars got? The MGF was astonishing - it seemed great when I bought it, but after heavy rain you could actually hear the water sloshing about in the sill structure. The Z3 has thick foam sealed to the underside of the carpet and I reckon there was at least two pints of water absorbed into that.

[cleverusername]

You're not going to want to hear this but if you strip the paint off that I would put good money on the fact you will find rot. That was what was causing the leaks on mine. I found them by waiting for heavy rain and sticking a torch behind the dash. What looked solid turned out to be rotten once I took a belt sander to it.

I hope I am wrong but I think your claims about rot are probably based on wishful thinking.

[Bradman]

I had similar problem. I tried the talcum powder route with the dashboard out (what a PITA!) but found nothing much other than a little water getting between glass and rubber on the front screen. I sealed that with clear silicone. Seemed to work for a while, but eventually I got wet footwells again, yet without evidence on said rubber . Then I heard a chap with a GT6 say that his car used to leak around the window wiper spindles, with water collecting in the metal box behind them until it had reached the right level to start dripping out through an access hole. I gave the spindles’s nut and washer some of that silicon and... no more leaks since

Edit: this is the same as Tony’s experience above

[Richard the old one]

I have produced an article for Dolly Mixture on water leaks into Dolomites and it might be in the next edition and I include in the article that the June 2020 edition of Practical Classics contained the following tip from Peter Harris who wrote “After a few flooded BL cars, our dealership discovered the most common cause was the windscreen wiper mounts.”

This is something I have also found is worth checking before blaming the windscreen seal. A couple of my cars have suffered to a relatively minor extent from this leak.

[Bumpa]

Further investigation of my car has shown conclusively that the water does not come from above - ie it isn't coming from the screen rubber or the wiper spindles. I am pretty sure it is getting under the edge of the gearbox cover. I had the cover out last summer and the rubber seal was knackered so I used a new self-adhesive rubber strip but it looks as though the seal is not good at the corner at the front of the footwell. The rain escaping from the heater plenum runs down the bulkhead and finds its way round the seal, entering where there is a weak spot in that corner, runs along the top of the sound deadening material and then spills over to form a puddle.

I have been under the car today and have tried to seal the outer edge of the gerabox cover, but access is poor because of the exhaust pipe. It is supposed to rain tomorrow. Let's see if I have made any difference.

[cleverusername]

Further investigation of my car has shown conclusively that the water does not come from above - ie it isn't coming from the screen rubber or the wiper spindles. I am pretty sure it is getting under the edge of the gearbox cover. I had the cover out last summer and the rubber seal was knackered so I used a new self-adhesive rubber strip but it looks as though the seal is not good at the corner at the front of the footwell. The rain escaping from the heater plenum runs down the bulkhead and finds its way round the seal, entering where there is a weak spot in that corner, runs along the top of the sound deadening material and then spills over to form a puddle.

I have been under the car today and have tried to seal the outer edge of the gerabox cover, but access is poor because of the exhaust pipe. It is supposed to rain tomorrow. Let's see if I have made any difference.

I had a leak in exactly the same spot and like you concluded it was the transmission tunnel seal. I was wrong, in reality it was a hole in the scuttle above the transmission tunnel and the water was tracking down from above. It look solid, till I removed the paint and found the metal behind had rotted away. The cure was putting in new metal.

[payload]

Can anybody explain the talcum powder method of leak tracing that has been mentioned in this thread? It's not something I have heard of before and I am intrigued!

[dollyman]

Can anybody explain the talcum powder method of leak tracing that has been mentioned in this thread? It's not something I have heard of before and I am intrigued!

You scatter talc everywhere then when it rains the water will leave a trace in it. You can then find the origin of the leak It does however cause serious injury if you use swmbo's talc without asking

Tony.