which silicon/

[Paulprior]

Hi

I am trying to find the source of water leaks into the footwells on my 95 Chimaera, the seal on the brake master cylinder cover looks a likely candidate, considering that this cover needs to come off drom time to time what is recomended to seal it with?
also any suggestions on how to remove all the old black silicon thats already there apart from scrapping at it with my nails?

Thanks

Paul

[bobfather]

It's not silicon, it's a polyurethane sealant. Silicon does not offer an adequate surface adhesion and breaks down easily. Use Sikaflex EBT

http://www.screwfix.com/p/sika-sikaflex-ebt-all-we...

[Magic919]

It's not silicon as that's nothing like silicone.

[Paulprior]

Hi
Not being familiar with Polyurethene sealers, what is the differance to silicon? what i have on mine is black and certainly has the appearance and feel of silicon, but the car is new to me so i have no idea what was put on

I will buy some Sikaflex this afternoon, does that remove easily for servicing?

Thanks

Paul

[bobfather]

Polyurethane sealant is a permanently flexible highly resistant sealer with very strong initial grab. It is similar to silicon in that it is flexible but tougher and less glossy when cured

[Paulprior]

Hi Bobfather

So what happens next time i need access, do i try and remove it all and start again?

Several of the rubber grommets to the right of the cover are also perished, any idea where i can get replacements from?

Thanks

Paul

[bobfather]

The sealant can be cut round with a craft knife and then just ease the cover upwards. I don't use new sealant any more because the old cut through polyurethane sealant acts like soft rubber and provides a watertight seal when the screws are tightened.

The rubber grommets on mine are okay so I have no knowledge about those

[phillpot]

bobfather said:

Use Sikaflex EBT

Sikaflex 221 dries with a smoother, glossy finish.


Unlike silicone, polyurethane sealants will stick to themselves so something like your cover can be carefully cut off then stuck back together with a light smear of sealant whereas silicone would need to be all cleaned off and start again.

[ianwayne]

Would this stuff do the job?

http://www.ebay.co.uk/itm/262199695738?_trksid=p20...

It has a good temp range and because of this, it could be used on the plenum as well maybe.

[sheel]

You can get the large grommets from powers performance in Coventry,they keep them on the shelf. Anywhere you have a penetration on the os front wing is a potential for water ingress,so check round the bolts,master cylinder reservoir etc,due to the design you really don't have much option but to gob it all up with sikaflex
Rich

[bobfather]

ianwayne said:

Would this stuff do the job?

http://www.ebay.co.uk/itm/262199695738?_trksid=p20...

It has a good temp range and because of this, it could be used on the plenum as well maybe.

Yes but only because the cover is screwed down. This isn't about heat tolerance, it's about surface adhesion and toughness. That stuff would do the job but not as well as a polyurethane sealant.

Car manufacturers often bond panels together and use sealants to prevent water ingress. It is very rare for them to use silicon, polyurethane is the industry standard. As an example, the rear lamp covers on Chimaera's are held in place with polyurethane, silicon sealants would not grab the surfaces strongly to maintain adhesion

ETA, silicon is used on engine components because of its inert properties. Silicon and polyurethane are very different materials with very different properties, because silicon is good for engine sealant doesn't mean it's good for body panel bonding and visa versa

Edited by bobfather on Sunday 24th January 09:39

[Magic919]

Silicon and silicone are completely different materials too.

[SILICONEKID345HP]

You need something you can easily rub off after maintenance .

http://www.siroflex.co.uk/sections/SXrange/TSsilic...