Car leak. Will silicone sealant stick to putty?

[Simon Robinson 4Participant @simonrobinson4]

My car boot leaks when it rains. I discovered the source of the leak. Under the rubber seal is a metal flange all the way around where two metal sheets meet. There is a very small gap as they were only sparsely spot welded during manufacture. The gap was filled with a kind of putty but over the years gaps have appeared in the join allowing water to seep in with capillary action and run down the inside under the seal and into the boot.

I covered part of it with gaffer tape and that stopped the the leak, but I want to go around the whole flange with silicone sealant. I discovered however that the putty is soft and malleable, like it had never cured. (The gap is less than 1mm in places making it impossible to remove the putty). My question is can I cover it with silicone or could it result in the silicone not curing or some sore reaction making it worse.

 

Thanks for any advice.

[JasonBModerator @jasonb]

Probably safer to get a tube of “seam sealer” plenty on the market for example

[JasonB]

On JasonB Said:

Probably safer to get a tube of “seam sealer” plenty on the market for example

Thanks. I’ll give that a try.

[Grindstone CowboyParticipant @grindstonecowboy]

A friend who did car bodywork always used Sikaflex 527 if I remember correctly.

Rob

[mgnbukParticipant @mgnbuk]

A friend who did car bodywork always used Sikaflex 527 if I remember correctly.

The same sort of PU adhesive sealant is used to seal motorhomes & caravans. Toolstation sell a PU sealant & I have used a similar product from there when I replaced a damaged TV ariel on a motorhome roof – far more robust & tenacious than silicone sealers & available in a range of colours.

Mask around the area & wear disposable gloves, as it is not easy to remove excess product.

Nigel B.

[OldironParticipant @oldiron]

As said earlier in thread use a seam sealer for caravans or Sikaflex type sealer.

As an aside I know a chap who used silicone to refit some windows in his house. The first time it rained the water poured in through the joints.

[noel shelleyParticipant @noelshelley55608]

Like Sikaflex,  CT1 at about £13 a cartridge is very good and FAR better than silicone. seems to stick to most things even when wet! Noel.

[Oldiron]

On Oldiron Said:

As said earlier in thread use a seam sealer for caravans or Sikaflex type sealer.

As an aside I know a chap who used silicone to refit some windows in his house. The first time it rained the water poured in through the joints.

Silicone does not have any joints so the water pouring in cannot be blamed on the silicone!

Ian P

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