Tyre Dust Covers

All Porsche Macan Related Discussion
B737NGWS
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Post by B737NGWS »

I also seem to remember that plastic TPMS valve caps (grey) have a couple of seals over standard (black) to better protect against water ingress and help prevent pressure leakage. There are indeed warnings on several tyre fitting websites against fitting ‘metal’ valve caps to TPMS systems.

Rarecolour
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Post by Rarecolour »

Nuclear Nick wrote: Tue Aug 17, 2021 1:53 pm
Fairynuff wrote: Tue Aug 17, 2021 9:49 am I wonder what is welding to what? What type of metal is the 'male' screw head on the tyre inlet valve - it looks like brass. I wonder what the chemistry/physics is behind two different metal types welding together without any heat?
The manual states that only plastic caps should be used. The reason is that two dissimilar metals with water present will set up a corrosion cell. The process will chemically bond the two metals together, so it’s not ‘welding’ in the true sense.
This ^^^^^
On my old car the previous owner put metal caps on the tpms valves, no chance of removing them without snapping the valves. They just corroded together.
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AndyC160
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Post by AndyC160 »

Nuclear Nick wrote: Tue Aug 17, 2021 1:53 pm
Fairynuff wrote: Tue Aug 17, 2021 9:49 am I wonder what is welding to what? What type of metal is the 'male' screw head on the tyre inlet valve - it looks like brass. I wonder what the chemistry/physics is behind two different metal types welding together without any heat?
The manual states that only plastic caps should be used. The reason is that two dissimilar metals with water present will set up a corrosion cell. The process will chemically bond the two metals together, so it’s not ‘welding’ in the true sense.
But porsche will actually sell you aluminium caps for £43 :? :roll:
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Nuclear Nick
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Post by Nuclear Nick »

AndyC160 wrote: Tue Aug 17, 2021 10:51 pm
Nuclear Nick wrote: Tue Aug 17, 2021 1:53 pm
Fairynuff wrote: Tue Aug 17, 2021 9:49 am I wonder what is welding to what? What type of metal is the 'male' screw head on the tyre inlet valve - it looks like brass. I wonder what the chemistry/physics is behind two different metal types welding together without any heat?
The manual states that only plastic caps should be used. The reason is that two dissimilar metals with water present will set up a corrosion cell. The process will chemically bond the two metals together, so it’s not ‘welding’ in the true sense.
But porsche will actually sell you aluminium caps for £43 :? :roll:
If you mean these - https://content3.eu.porsche.com/prod/pa ... 07004B1426 - they are sleeves, not metal caps. Beware of non Porsche parts for sale elsewhere.
Nick

Defender 90 V8

991.2 C2 GTS

Macan Turbo - sold

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AndyC160
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Post by AndyC160 »

Nuclear Nick wrote: Wed Aug 18, 2021 7:05 am
AndyC160 wrote: Tue Aug 17, 2021 10:51 pm
Nuclear Nick wrote: Tue Aug 17, 2021 1:53 pm
The manual states that only plastic caps should be used. The reason is that two dissimilar metals with water present will set up a corrosion cell. The process will chemically bond the two metals together, so it’s not ‘welding’ in the true sense.
But porsche will actually sell you aluminium caps for £43 :? :roll:
If you mean these - https://content3.eu.porsche.com/prod/pa ... 07004B1426 - they are sleeves, not metal caps. Beware of non Porsche parts for sale elsewhere.
Ah...my mistake. Do they slide over the plastic caps then?
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Nuclear Nick
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Post by Nuclear Nick »

AndyC160 wrote: Wed Aug 18, 2021 6:50 pm
Nuclear Nick wrote: Wed Aug 18, 2021 7:05 am
AndyC160 wrote: Tue Aug 17, 2021 10:51 pm

But porsche will actually sell you aluminium caps for £43 :? :roll:
If you mean these - https://content3.eu.porsche.com/prod/pa ... 07004B1426 - they are sleeves, not metal caps. Beware of non Porsche parts for sale elsewhere.
Ah...my mistake. Do they slide over the plastic caps then?
I don’t have personal experience of these but from the description that is what they appear to do. And it would be consistent with Porsche’s recommendation to only use plastic caps.
It’s very possible that there are non Porsche caps available that are metal but, again, are to be avoided I would say.
Nick

Defender 90 V8

991.2 C2 GTS

Macan Turbo - sold

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Neil1911
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Post by Neil1911 »

For the record, the Porsche OEM caps I bought from Amazon, link posted above but "currently unavailable", are plastic and at £22.57 might almost seem too good to be true. Can't find it now but when ordering something gave me the impression that they were from America.
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