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Porscheaddiction · Posted: Mon Jun 20, 2005 1:20 am Post subject: Exhaust Manifold questions

Ok I am judging by the weight of the exhaust manifold, I am assuming this is a cast iron or steel part? what would be the best way to clean it up its all brownish(rusy) in colour and if its possible would like to clean it.
Thanks
Chris.
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1981 924 NA (Restoring mode)
1984 928S (Enjoying the driving season)

augidog · Joined: 03 Mar 2003 Posts: 1360 Location: New Jersey

High temp paint worked on my heat sheild. Wal-mart sells cans in the auto section.That paint has been holding up well so far.
Red would be a nice color for a hot exhaust manifold.
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1978 924 95 mile daily driver.
Audi TB/POR174M/High Flow Cat/2.25" exhaust
I knew that positive thinking thing wouldn't work.

Porscheaddiction · Posted: Mon Jun 20, 2005 3:03 am Post subject:

ok thanks for the paint tip..now how about cleaning it before painting? whats a good way to clean it.
Thanks
Chris
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1981 924 NA (Restoring mode)
1984 928S (Enjoying the driving season)

Diesel · Joined: 03 Nov 2002 Posts: 1061 Location: Ellington,CT

Sandblast it.
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Dan Flanagan--2002 VW Jetta TDI, 83 Mercedes 300D,83 Mercedes Euro-240D

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

If your talking about the actual exhaust manifold itself no paint ,hi temp or not, will last for more than 1 minute without burning off.That manifold gets so hot it's almost see- through.And as for that rust coloured stuff-it actually acts as a protectant for the parent material underneath,kind of like a really hard coat of paint.It helps keep the salt and other nasty road crud from attacking.The only reason to take it off is if your worried about cracking underneath.Oh and yes it is made from cast iron not steel.
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1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

Mike924 · Joined: 12 Aug 2004 Posts: 2601 Location: IoW UK

Diesel · Joined: 03 Nov 2002 Posts: 1061 Location: Ellington,CT

On my n/a, I sandblasted the manifold with aluminum oxide then painted it with silver high-temp paint. I used 2 coats and went by the directions on the can as to how long to wait between coats and when to 'heat it up'. It still looks like new.
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Dan Flanagan--2002 VW Jetta TDI, 83 Mercedes 300D,83 Mercedes Euro-240D

CBass · Joined: 03 Nov 2002 Posts: 2807 Location: Vancouver, Canada

Depends on whether it's stock or not. The stock manifold is made of cast iron, and looks like this.

It has two pipes coming out of it, which merge after a couple of feet.

No benefit to painting it really, unless you're really concerned about underhood temps and maximizing efficiency, which you shouldn't worry about unless you've already replaced the exhaust system from the downpipe back with a bigger pipe and removed the cat.

If you just want to do it for looks, sandblast it and use high temp paint like suggested. Doesn't really matter which colour, since the big heat issue is going to be manifold to air transfer of heat.
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'81 931 in various states of assembly