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Corrosion underneath the car [rust]

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Dear fellow members,

I would be extremely grateful to you if you could give me your opinion on the following matter: I discovered underneath my car the very corroded following part [see e.g. picture]. I've treated the part with an anti-rust product and covered it with a high resistant temperature transparent paint. My car is a four months old 997. Before the treatment, the part was all covered with red rust. The picture below is after treatment.

Well, is that normal?

I would be interested to know if you've experienced the same "flaw" on your 996s or 997s, and if you've applied a treatment in the case of corrosion of this particular part.

However, be very attentive to the fact that this part is very hot after engine operation.post-3260-1112119150_thumb.jpg

Edited by zacharie
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It is quite hard to see, due to the close proximity of your photograph, but it looks as though this is part of the exhaust manifold. If so, these parts are made of a cast material, (not sure if it is actually cast iron) and it is very normal for them to have a 'rusty' appearance.

The 'rust' is a surface patina or oxide that forms, however this never gets worse to the extent that it begins to rot away - once formed it prevents further or deeper oxidation.

You say the surface gets very hot in normal use, if it is the exhaust manifold, expect temperatures in excess of 600C. The workshop manual is quite particular that no part of the exhaust system needs or should be treated with any corrosion protection, be it underseal or paint.

The use of this material for exhaust manifolds is not peculiar to Porsche.

(However, I'll eat my words with Humble Pie if this is not your exhaust manifold..!)

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Thank you for your response. Yes indeed, it's a part related to the exhaust manifold [see picture, bottom of part number 5] . In fact, it is the systems support for the exhaust manifold. The paint I put on as a protection is called Thermo 600 from Julien [a french product]; the formula is studied for temperatures approaching 600 degrees celcius.

Do you think I should remove the paint and let it get rusty as day one?

Have you already observed that rusty film over the system support?

Orient Express, if you read my post, may i also ask your advice please?




Edited by zacharie
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That may not be corrosion, but rather burnt or cooked cosmoline. Notice the white stuff on the headers? That is burnt cosmoline as well. I had the same issue around the exhaust manifold when my car was new, but it cleaned up quite nice with some mineral spirits and steel wool.

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