General Fiat 500 rain water leak - running out of ideas

[Splash]

Fiat driver's side footwell is wet. Water appears to be weeping from the front seat mounting / front box section area and creeping to the edge of the inner sill and floor join - a low spot.
Water leak is more apparent after driving the car. I struggle to get it to leak with a hosepipe. The water is definitely rain water.

Sills are totally dry inside when I take out the inner sill rubber grommet.

However, the chassis leg has water in it when I take the rubber floor bungs out underneath, under the front seat area.

Door seal is fine - no water passes.

Car doesn't have air con.

I thought it was the rear side window leaking and trickling down near the seatbelt pretensioner, but I've had the seatbelt area/rear window side trim out and it is all dry, even the sound deadening in the rear quarter - and I've tested with a hosepipe. Likewise the roof bar area is definitely not leaking.

Bulkhead is dry and the usual suspect drain rubbers under the bonnet are clear and working.
Rear of the car is dry, water is not travelling from the rear.

Any ideas when the water is coming from? Any ideas how water could get in the chassis leg? I am thinking that water is getting in the chassis somewhere and creeping through seams when the car is driven against rain/wind.

Any suggestions much appreciated as I'm running out of ideas!

 

[chris3234]

I vaguely remember something about water finding it's way into the box section in the center of the car


Try removing any blanking grommets around the rear of the car where a towbar would bolt onto the car if it had one

 

[varesecrazy]

Pretty sure somebody had a roof seam fail . they stripped back the rubber sealing strip and sealed it in

 

[Baglady1990]

Pretty sure somebody had a roof seam fail . they stripped back the rubber sealing strip and sealed it in

With all the rain we are having here atm if the leak is still present… the car will be a swimming pool by now!

 

[chris3234]

Found the post been looking for this a few times this is the post I had seen


Post in thread 'Flooding in footwell behind passenger seat!' https://www.fiatforum.com/threads/flooding-in-footwell-behind-passenger-seat.464892/post-4378103

 

[Ralf S.]

If memory serves me well, Once Upon a Time on the Alfaowner forum, there was a similar spate of leaks on the Alfa 156.

I think the issue there was that water was getting in on a poorly sealed (factory) seam at the leading edge of the floorpan, although not having a 156 or any leaks, I didn't pay too much attention to the thread and didn't have a look for any similar spots on my 155/145 I had at the time.

It sounds like yours could be something similar, particularly if the car has had an interesting history.

If you have the chance/can blag it, it may be worth taking the beast to somewhere with a ramp and let them jack it up for you to have a look at the underneath. If there's any welded seam around the wheel arches, or just inside the engine bay then that may the culprit. If you remove the wheel arch liners and have a look behind them, where the wheel arch is welded/sealed to the body side of the car, then that might be a likely spot too.. the roof drains just dump water behind the liners, so the seams here have to be well sealed.

If the car has or may have had an interesting history then the n/side front corner may have been been accident repaired. Quite often the mastic on a welded seam becomes split when the panel is distorted but the split becomes invisible when the panel is pulled straight again and the mastic closes over the split. It needs re-sealing... I've used a spot of silcone gasket goo or body filler in the past, with good results.

If you can't blag a Lift, then jack both sides of the car up, rest it on axle stands and then crawl under there with a cup of tea and a torch. If you spend a half hour under there just looking upwards you can sometimes spot different things that don't appear when viewed from above.



Ralf S.

 

[Splash]

Thanks everyone for the helpful replies.

I've crawled all over the car, inside and underneath on ramps, and it seems very original - no evidence of crash damage - but like Ralf S says, it only takes one small area of cracked seam sealant to allow water ingress.

One area I'm going to investigate on Thursday - my day off - is the rear bumper bracket area. After reading a couple of posts about Ford KAs it is fairly common for the sealant to allow water to pass into the chassis leg and make its way through the underfloor seam. I'll take the outer bumper plastic off and the bumper bar and re-seal the bolts/bracket. At least this way I can then rule it out even if it doesn't work.

I'll report back after my exploration on Thursday - with pics if I manage to cure it! Thanks again!

 

[Splash]

I've had the plastic bumper and metal reinforcement bar off and the car was clearly letting in water between the chassis end and the bumper bar brackets.

Both chassis legs had water in them - although only water from the driver's side is getting into the car. You can see how the water has travelled by the dirt - and some of that same dirt was inside the ends of the chassis legs.

I cleaned up the faces, treated the rust and sandwiched polyurethane sealant (Puraflex 40) between - and once bolted back into place I used the same sealant around the edges/seams and on the screw threads.

For the time being I have removed a few rubber plugs on the chassis to allow the water to escape but they will be replaced in a few weeks when the box sections are fully dry inside - and waxed.

I hope the pics below tell the story and help others in future. I also hope this is the end of the water ingress - I'll report back in a couple of weeks after a thorough test!

 

[chris3234]

Allways good to get a reply saying the issues has been solved

 

[Ralf S.]

That's a similar setup to my Stilo, although the ones on the Stilo seem to be more sheltered. My channels had evidence that they occasionally got water/dirt carried into them, but no flooding in evidence..

Your fix looks very thorough... I hope this is it and fixes it, rather than the real leak is still to be discovered...

Ralf S.

 

[Splash]

After several bouts of torrential rain I can now confirm that the car is bone dry and the leak totally FIXED!
I hope this thread helps others in future. Thanks for everyone's input.

 

[Baglady1990]

After several bouts of torrential rain I can now confirm that the car is bone dry and the leak totally FIXED!
I hope this thread helps others in future. Thanks for everyone's input.

Wow ok thanks so much for the info! Glad you got it sorted… I’m thinking I’m going to have the rear bumper off now to have a good look myself

Fancy there being holes … nice large ones too

 

[thorn1979]

After several bouts of torrential rain I can now confirm that the car is bone dry and the leak totally FIXED!
I hope this thread helps others in future. Thanks for everyone's input.

I have the same ingress issue and after much faffing with watering cans I don't think the door seal is to blame, and given how wet the drivers side carpets are I'm wondering if I have the same issue. How much of an arse is the bumper to remove?

 

[John202020]

I have the same ingress issue and after much faffing with watering cans I don't think the door seal is to blame, and given how wet the drivers side carpets are I'm wondering if I have the same issue. How much of an arse is the bumper to remove?

first check your duck bills that drain the scuttle area 10 min job and free

 

[thorn1979]

first check your duck bills that drain the scuttle area 10 min job and free

Done already.

 

[John202020]

When parked is the car level, nose up or nose down?

 

[thorn1979]

When parked is the car level, nose up or nose down?

Flat. Spare wheel well is dry.

Both front and rear footwell carpets are swimming, driver's side. I've pulled them up as best I can and removed the side trim inside, then watched for dribbles whilst the o/h has poured water over - door seals all seem fine, nothing coming through. I have suspicions that water is creeping in at the front where the bonnet hinge is, but not enough to account for what I'm seeing. Duckbills are all clear.

Although there's nothing in its history, there *is* accident damage to the rear quarter on that side - the lousy paintwork was a giveaway. I wonder if there's a seam underneath that's distorted and not sealing. I'm going to wait for a nice dry day when I can spend the whole day at it, get the bumper off, and check the bumper mounts and chassis rails for water. Bit scared of what I'll find under there if I'm honest!

Got to replace one of the front wheel arch liners too which is going to be a fun job *sigh*

I'm only keeping it cos it's purple.

 

[varesecrazy]

Damaged liner on the doorskin a possibility?

Being a 500,
as likely through a handle repair as through accident damage..

 

[thorn1979]

No.. the impact area looks to have been on the o/s rear wing below the filler cap, so not the door.

 

[varesecrazy]

No.. the impact area looks to have been on the o/s rear wing below the filler cap, so not the door.

Others have found its the door membrane.. Have you checked it?