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MG MGF Technical - Soggy passenger footwell, that old chestnut

Apologies for not doing a full search of the archive (I'm sure there's loads of info there), but I'm severely lacking time to look at work today, and I'd like to tackle the problem tomorrow.

Soggy passenger footwell....that old chestnut.

Common fault as I understand, and seems (logically) to be worse when I park with my nose pointing uphill. I'm 99.9% sure this is down to a duff heater box inlet seal. After reading the recent 'Leak' thread on the General board, it seems that the quickest, cheapest and easiest solution is to access the heater box from inside the car after taking the glove box off (as opposed to removing the black plastic cowling under the bonnet) and apply liberal amounts of silicone sealant. Agreed?

My questions are:

(a) Is there anything else I need to look out for when trying to sort this imbuggerance?

(b) Will I be able to dry out the felt/soundproofing under the carpet by chucking it in the tumbledryer (don't tell the missus), or over a radiator, or will I be better off chucking it and getting some new stuff.


Jim Hosking


If it is just the passenger side wet then you are probabbly correct that it is the heater box causing the problem so yes silicon sealant will fix this.

As for other things to look out, when I did mine any panel which gave access to the front and could be removed I did and put extra silicon sealant on just for piece of mind.

As for drying out the soundproofing I normally just let it dry naturally and I would leave it out just to confirm that the leak has been fixed before putting it back, although I did this a number of times thinking the leak was gone but due to the normal carpet being thiner it did not retain water thus hid the fact that it was still leaking (this is drivers side passenger side was an easy fix)

Tom Randell

Thanks Tom,

Yep, it is just the passenger side.

Depending on available time I might whack a load of sealant on the join bonnet side as well then. Got the impression from another thread that it was a bit tricky to get to. Any handy tips on this?

Also, will I need to remove the passenger seat to remove the soundproofing, or will it just come away with a good tug? I'm not too fussed about removing the carpet as well, as I'm sure this will dry off pretty quickly being so thin.

Jim Hosking


I did sealant on both sides but yes it is tricky doing the bonnet side specially getting at the fixing nuts but once loose I just cleaned it and then put loads of sealant everywhere and then refixed it. I seam to recall a long socket extension was needed to get at one nut which from memory is behind the brake master cylinder which was tricky. It was easier putting it back together.

I must admit I never removed the passenger side, but if it is the same as the drivers side it should be easy as it should just come out by removing the clips which keep the carpet in place and then fold the carpet back to reveal the sound proofing.

There should be no need to remove the seats.

Tom Randell

Also, check the blind grommet next to where the cables go through the bulkhead (RHS as you look at the car from the front next to the air box). Mine had a blob of paint around the hole and the grommet wasn't seating properly, allowing water to drain into the passenger footwell.

Good tip John - I'll check this as well.

I'll post a progress report on Monday!

Jim Hosking


If your MGF is from the early models then make sure that it has the cutouts in the bottom edge of the door seals. There should be two cutouts each side. They are one at each end of the chrome kick plates. These are easily seen when you open the doors.

The actual door seal rubbers act as hollow drain pipes and it was found that the drain holes in the bottom edge of the seals needed enlarging to prevent them from becoming blocked.

Whereabouts are you in Warwickshire? I live near Rugby.

Bruce Caldwell

I took the seats out and the carpet and stuc kit in front of the fire to dry.I take it youve read the posts on the general board about this where i explained about the heater box. As i said at the time i simply extended the water deflection plate, but have since found that even that isnt good enough.So what ive done now is sealed up the inlet where the air comes in next to the wipers and cut a hole in the side of the heater box under the bonnet, this works alot better as no water can run into the heater box anymore with the inlet now being on the side rather than the top. remembering to seal the gap between the top of the box and the plate where the wipers are top prevent water running down the back and onto the foam seal
. C

Hi Bruce,

I do have an early F ('96 MPi) IIRC, I think I have at least one door seal cut-out on each side, but I'll have to check whether I have 2. I'm based in Leamington mate, however off to Rugby this afternoon for a Sunday Roast! N336 CAJ - if you spot me at any time give us a wave!

GC, thanks for the tips. Like you I'd like to avoid going for the full heater box replacement, so this advice gives me a couple more options if silicone sealant alone doesn't work.

Thanks all!
Jim Hosking

Ok, well hopefully that's problem sorted.

Set about solving my sodden passenger footwell today by applying generous amounts of silicone sealant around the heater box inlet. If anyone else has this problem then follow the instructions below for (touch wood) a cheap and easy fix.

(1) Remove the glovebox. There are 2 screws (philips) underneath the closed box, and 2 inside the open box. Carefully lower the box and unplug the 2 alarm connections, and 2 glovebox light connections (these just pull free). The glovebox will then just lift out.

(2) Lift up the carpet in the passenger footwell (by removing the round plastic fixing plugs) and take out the felt soundproofing underneath. To remove the felt at the front of the passenger footwell you'll have to unscrew (just using your fingers) about 4 plastic plugs. This section of felt disappears under the centre column, so I had to Stanley knife it away. All the felt was absolutely sodden and there's no way this would dry out in the car so let it drip dry over the bath then hang it over a radiator or in front of the fire (‘er indoors allowing).

(3) At this point you can check that the heater box inlet is the source of the leak by tipping a glass of water down the grill above the bonnet (where the windscreen wipers are). In my case water then started coming in through the foam seal on the underside of the heater box inlet. You shouldn’t have to look too hard for this, I was surprised by how much actually came in!

(3) Some back plastic hosing (leading to the air vent near the wing mirror) runs in front of the heater box air duct. Unplug this at the top to give you clearer access.

(4) Remove the air duct by taking off the single retaining bolt. See link below (courtesy of Rob Bell)

(5) Create a new gasket using automotive silicone sealant (cheap and available from Halfords). See link below (again, thanks to Mr Bell)

You’ll look slightly daft, but easiest way to do this is upside down with your head right inside the footwell. Not too comfortable, but needs must! Pipe liberal amounts of silicone sealant around the foam seal, wait 10 minutes and then re-attach the air duct, and air vent hosing.

At this point I’ve just put the carpet back in place, and have yet to re-attached the felt soundproofing and glovebox. I’m going to wait until the sealant has cured before testing that the leak has been plugged before putting these back. Also gives the felt a chance to dry properly.

Really quite a simple job, and will save you quite a few quid.

Hope this helps anyone with the same problem.

Jim Hosking

Nice one Jim,

Will look out for you. Mine's a Flame Red P503PRJ. Didn't see you but spent half the afternoon trying to jump start an F355! LOL. Battery been dead for weeks.

Hope the leak is fixed now. Leaks become a bit of a game, you versus the car.

Bruce Caldwell

I think it is better to have the old air box replaced with the new part. It is better sealed and has bigger drain holes. The thing to be careful about using sealent is that if done incorrectly it can make the problem worse. I had a dealer try to fix it and he sealed all around the box meaning that even less water escaped and the problem got worse. So it is important when sealing that you increase the size of the drain holes in the bottom of the box.

As for removing the plastic cover under the bonnet or removing the glove box. The plastic cover under the bonnet is easier to remove and you will have to do this anyway to put the drain holes in the box.

Another leak problem in the area is the plate that covers where the steering column goes on a LHD car this can sometimes leak road water through the seal. In this case sealent is the way to go.

Bruce, spent half the afternoon playing with a Ferrari eh! I hope you got to take her out for a canter afterwards!

Know what you mean about leaks becoming a bit of a game. Hopefully that's 1-1.

T.E.D, Take your point about enlarging the holes at the bottom of the box, this can only help, so I may do this as well when I have some time.

Jim Hosking

Nice work Jim :o)

Been planning to put this info on my web page for donkeys - perhaps now is the time! LOL

Do you mind if I reference your instructions on my site?

Rob Bell

Be my guest Rob - they are your pix after all ;o)

Jim Hosking

Cheers Jim ;o)
Rob Bell

Another cause of a flooded passenger footwell is the blanking plate thats fitted over the hole where the steering column would come through the bulkhead if the car was L/H drive, removed and resealed it on the wifes car and the carpets have been dry ever since.


I think we have an Echo here :-)



You're right Tony.
Bruce Caldwell

LOL Bruce!

Well, the attempted fix had it's first proper test in last night's deluge, and I'm happy to say that the passenger footwell was as dry as a bone this morning :o)

The soundproofing is now thoroughly dry so that will be going back in tonight along with the glovebox.

I wonder where my next leak will come from....

Jim Hosking

This thread was discussed between 08/11/2002 and 13/11/2002

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