The door seal rubber on my 93 318iS has started to harden and I now start to get some wind noise above 60. BMW quote over £100:00 for a replacement. I have looked at other parts sources,but cannot find another supplier.
Doea anyone know of a way to resolve this at a reasonable price?
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Treatment with a product like Back-to-Black (silicone?) might help the seal to conform to the shape of whatever it seats against when the door is closed, i.e. it might make it slide rather than stick. It might even partly restore the flexibility.
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Silicone rots natural rubber, if the seals contain any natural rubber, it will make them hard over time, as it leaches in and drives out the natural resins.
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Silicone rots natural rubber, if the seals contain any natural rubber, it will make them hard over time, as it leaches in and drives out the natural resins.
sooty tailpipes
i am very interested to find out source of this information.
i was aware of reaction between petroleum-jelly and natural rubber.
but the above claimed reaction with silicon is news to me and so would appreciate further details from you.
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Hello, I recall reading this when I used to deal with o-rings, in the Zymol catalogue and on a tyre manufacturer's website who said perishing was caused by ozone, uv light, lack of use, and preparations containing silicone.
I have just done a quick seach on the web... and here is an example.....
Armor All? NO! There are processing and protective additives already formulated in the rubber compound. Putting Armor All on your bands will protect them, but it also replaces those compounds already there - and if the compounds in Armor All were better, they'd use that in processing. The compounds in Armor All and other compounds (silicone oil included) will swell the rubber. What does a swollen rubber mean? (Well, have you ever used a condom with a petroleum based lubricant?) Swollen rubber is weak as the chains on a molecular level are stressed even more, relaxing the physical crosslinks, allowing more stretch with less resistance, and premature failure.
Silicone oil, in addition to swelling the rubber, is extremely permeable to oxygen - oxygen doesn't even slow down when it hits silicone. This means that using silicone on your bands will swell them, weaken them, and provide no barrier to oxygen. There are some commercial bands available that are rubber with a thin silicone rubber coat over top of them. This coating does nothing to stop oxygen. Silicone also has a very poor tear strength - once a nick starts, it propagates very readily. The silicone coating is bound to the rubber - so when it nicks and tears through the coating, the tear is introduced into the underlying rubber more easily. There are also bands out there that are coated with polyurethane, and these are more durable and offer extended life, though I'm not sure which brand uses which.
I will be the first one to admit, however, that I use silicone oil and acetone to swell rubber and make bungee's with it - but those are easy enough to make that replacing them often isn't a problem.
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I can add to this thread that I've used Armor All on my Cavalier's door & boot rubber seals from new - applied about once a year for over 15 years and they are supple and look & seal like new even now.
In a recent Watchdog programme about the leaking Citroen Pluriel roof problem, I was inteested to see certain dealers are recommending Vaseline on the leaking rubber roof seal joins as a get them out of a warranty problem solution! Not to be recommended I would have thought.
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I suppose it al depends on the material used, and we have no way of knowing what it is, eg.
www.marcorubber.com/materialguide.htm
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Interesting information from Sooty Tailpipes regarding silicone and its effect on natural rubber; I knew nothing of this. However I'd be very surprised if there is any natural rubber used on today's cars, more likely that the door seals are nitrile or EPDM rubber.
I'm bookmarking the 'marcorubber' link in the follow-up posting from Sooty because the information in it looks reliable and it's easy to take in. I haven't studied the whole site but I don't think it mentions that Viton is both very expensive and very hazardous when hot (as in a car fire) so, although it would perform better than others for door seals, it won't have been used for that purpose.
Incidentally, I used a silicone spray on the door seals of my BMW for three years and I feel sure that they were in better condition (more supple) at the end than at the start.
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Interesting information from Sooty Tailpipes regarding silicone and its effect on natural rubber; Incidentally, I used a silicone spray on the door seals of my BMW for three years and I feel sure that they were in better condition (more supple) at the end than at the start.
i too believed that frequent advice on this forum said use silicone spray on door seals. apparently because silicone grease oil is supposed to be inert.
now we know different. maybe the same lesson the implant plastic surgery industry learnt that silicone is not inert?
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Dalglish,
*Do* we know different? Did you find that silicone damaged your door seals?
Unless I read it the wrong way, ST's source said that silicone damages natural rubber; it said nothing about damage to the synthetic rubber that car components will be made of.
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Dalglish, *Do* we know different? Did you find that silicone damaged your door seals? Unless I read it the wrong way, ST's source said that silicone damages natural rubber; it said nothing about damage to the synthetic rubber that car components will be made of.
the bit that i didnt know and now i know is different is as per sooty earlier post
" Silicone rots natural rubber, if the seals contain any natural rubber, it will make them hard over time, as it leaches in and drives out the natural resins. "
it is that post which provoked my question because i did not know silicone had any effect on natural rubber.
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I suppose it all depends on the material used, and we have no way of knowing what it is ... >>
I don't know how strictly it is applied these days but some of the rubbers used to be identifiable by their colour. For example, silicone was red and Viton was blue. Nitrile was always black and I think EPDM might also have been black (or was it grey??).
O-rings and lip seals in particular complied with these colour codes. It avoided items of like dimensions but different composition getting mixed up.
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natural rubber has a distinctive odour, so I suppose one could rub the seal to release the smell from the suface and smell the door seal. Thinking avout it, I doubt there would be any natural rubber in door seals, there is in tyres, and radiator hoses though!
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BMW make a special cream for door seals called Gummi Pfledge, about £5 a tube, works a treat, even on Citroens!
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