# stainless



## hesslevtr (Jan 2, 2006)

i have a stainless manifold on my car and has gone brown rusty colour

what products would you use to get it back to its best like the heat soaked blue/purple colour

hope that helps










all tacky blue pipes have gone btw


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## James105 (Oct 16, 2006)

sure its stainless, coz stainless steel doesn't rust, hence why its used in cooking utensils and pots.


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## markyboy.1967 (Feb 6, 2006)

*Manifold*

Doesnt look stainless to me. Looks like a standard one, closer pics would help as it may be just the pic, if this is the case then i dont think anything will bring it up unless you have it removed, bead blasted and coated...


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## Clark @ PB (Mar 1, 2006)

looks like the mild steel Ashley one i had on my saxo, which rusted once all the "heat proof" paint had flaked off!


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## Gav (Mar 9, 2007)

its a saxo they are crap. hehe. im starting to miss mine a bit now. get on msn i got me pc on monday.


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## hesslevtr (Jan 2, 2006)

yup its a stainless one from gmc motorsport

it did have that heated bluey purply effect then went like that


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## James105 (Oct 16, 2006)

id be very surprised if a stainless steel one did that, coz the physical material properties of stainless steel mean it doesnt rust. Are you sure it wasnt plated, and then plated surface has come off?


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## hesslevtr (Jan 2, 2006)

im not sure 

i did get alot of oil over the engine when the oil filter went pop good old citroen fpr you

its coming off soon so il get some autosol and wire wool on it and see what hapends


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## Clark @ PB (Mar 1, 2006)

GMC did staninless and mild steel ones didnt they? (or still do?)


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## hesslevtr (Jan 2, 2006)

yeah they do both this is stainless 

it did go a bluey/purple colour then just faded like this and i dont think the oil helped


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## PETER @ ECLIPSE (Apr 19, 2006)

doesnt look like stainless to me quick check , get a magnet if its stainless it wont stick


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## calibrax (Mar 22, 2007)

Stainless steel comes in different grades - some of them are prone to mild surface rust.


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## cravensmythe (May 26, 2006)

I have noticed that stainless manifolds or even back boxes that are very close to the engine i.e. beetles tend to tarnish, not rust but go a brownish colour. I think this is why you can by ceramic coated ones that maintain their shiny stainless look even with very high temperatures.


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## parish (Jun 29, 2006)

calibrax said:


> Stainless steel comes in different grades - some of them are prone to mild surface rust.


Indeed. Practically any steel that contains chrome and nickel as alloying elements is classed as stainless.

The grade used for cooking utensils etc is 18/8 (18% chrome, 8% nickel) and I think you can get up to something like 24/12 or 22/10.

There are also many "utility" grades with much lower proportions of chrome and nickel (and the other alloying elements). Note that these lower grades *are* magnetic so the magnet test isn't 100% reliable.

When I worked in the sheet metal fabrication business 18/8 stainless was something like 8-10 times the price of mild steel so it's highly unlikely that car exhausts are made from it but rather a low grade utility stainless which, as others have pointed out, will acquire surface tarnish and rust - aggravated by the high temps involved, especially the manifold. The advantage is that you can use chemically aggressive cleaners on stainless but remember that your ally block and head, and the radiator may not be able to tolerate such products. Something like Megs Wheel Brightener used neat, or nearly neat, may be worth a try.


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## PETER @ ECLIPSE (Apr 19, 2006)

dont want to contradict , but what would be the point of using lower grade stainless on a manifold if it is stainless it will probably be either 316 , which is a common hard wearing stainless, or 304


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## parish (Jun 29, 2006)

peter richards said:


> dont want to contradict , but what would be the point of using lower grade stainless on a manifold if it is stainless it will probably be either 316 , which is a common hard wearing stainless, or 304


Price. Unless the system is on show (under normal circumstances, I'm not talking about show cars here) - e.g. the tailpipe - then I wouldn't imagine anyone making a system out of a more expensive material than necessary. Also, life expectancy would come into it I expect - what's the point of an exhaust system with a life several times that the likely life of the vehicle it's fitted to?

I've been out of the engineering business for a good many years now, but I recognize the numbers - AISI (American) aren't they?

The company I worked for made those streetside cabinets for cableTV and we got a contract to make a version of it for railway trackside use (signalling gear etc.). The requirement was unpainted stainless with a working life of at least 75 years. We found a utility stainless that was only something like 2-3 times the price of mild steel that met the requirements. I can't remember the spec now but it was both magnetic and would form minor surface rust - more like tarnishing - after just a couple of weeks outside (we were on the coast - literally - so salty air).


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## PETER @ ECLIPSE (Apr 19, 2006)

apart from the bits that are visible , the main reason for using stainless is for the hard wearing properties it has , thats why the companys offer a lifetime guarantee once fitted.
i remember when i had my capri 280 it was going through exhausts like nobodys business . so i fitted a full stainless system from a company called power and engineering , lifetime guarantee on it and in the long run saved me quite a bit of money , and i think that was 316 fully tig welded , which is stronger than mig


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## Wozza (Mar 3, 2007)

SS does come in different grades, and if it it cheap it will rust, apart from that, mixing different metals can cuase issues, see info below taken from a website. It may not be the same metals but you should get the idea.

Aluminium does not mix well with the stainless steel - in fact aluminium WILL corrode if water is in contact with both materials.

Electrolytic corrosion works on the same principles as a battery. Two metals, an anode and a cathode, are placed in fluid and an electrical reaction takes place which results in the softer metal being eroded due to electrolytic corrosion. Once these conditions are met, a "corrosion cell" is created, an electrical current will flow and metal will be consumed at the anode. The only way to remove this corrosion is by using metals of the same electromotive force (EMF).

For example, Aluminium has an EMF of +1.66 volts and stainless steel an EMF of -0.34 volts. When these two metals are in contact in the presence of a fluid (rain water etc) the electrolytic corrosion outlined above must take place resulting in the erosion of the anode (the positively charged metal in which in this case is aluminium). The greater the difference between the difference in the EMF's of the two metals the greater the level of corrosion


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## Affection to Detail (Jul 6, 2006)

I know of companies that have offered lifetime garuntee's on so called stainless steel exhausts then havent hounoured it. When I had my exhaust made up they went through all the materials made with me and had samples from other companies. I have since been back for bracket repairs FOC etc. No rust on the system, just slight discolouration as expected. My SS exhaust used to be blue and silver, but over time it will discolour. The thing is some discoulouration is deep and you'll be hard pushed to get it off.

My opinion is get it ceramic coated.


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## hesslevtr (Jan 2, 2006)

woah that got a bit technical for my little brain

it will be coming off soon and il give it a polish woth some wirewool and autosol see what hapends 

thanks for all the help


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## kp 115 (Mar 5, 2007)

if you speak to a welding supply company you should be able to purchase a pickling acid/paste that is used to clean up the heated area after tig welding,

I think you would only use this if the manifold was removed though as Ithink it contains Hydrochloric acid !!!

hope this is of help.


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## westie (Mar 28, 2007)

I cant say that this is stainless, but if you bought it as such, from a good supplier, then it must be. The trouble with stainless steel there are many variants, and yes some of them do rust.The main type of stainless steel seen in the home is on saucepans and cutlery, this is grage 18/10 with basically means that it will never rust even in left in the sea, down to the cheaper grade that do form mild form of surface rust or oxidise.
The sorry thing thing to say if yours has gone that way there is nothing you can do, appart from cleaning it up with wet and dry paper, it will then oxidise again


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## Benskett (Nov 6, 2006)

Welders 'pickling paste' - You will never remove the tarnish because the heat will bring it back.


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## rst1990 (Apr 29, 2007)

Mmmm stainless? you shore? souldnt have surface rust on stainless


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## trionic (Oct 3, 2006)

That's cheap stainless steel. Looks great and then quickly looks cak.

The solution would be to remove the manifold, take it to an electroplater an say "fix this". They'll chemically remove the rust and plate the material appropriately. Then it'll be fine for years. Would cost about £40.



peter richards said:


> dont want to contradict , but what would be the point of using lower grade stainless on a manifold if it is stainless it will probably be either 316 , which is a common hard wearing stainless, or 304


How many folk ask which grade of stainless will be used in the manufacture of their new manfold? Not many. So suppliers of the type who might advertise in Max Power cut corners and use cheap stainless.


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