Problems with OE exhaust mainfold (how to repair ?)

[DamirGTI]

Hello !

Please can somebody help me out (Guy or somebody else ?) , i need advice regarding exhaust mainfold repair .
It's OE Peugeot 205 GTi exhaust mainfold and it blows out at the corners , I've try all sorts of mainfold gaskets , sealants etc. but all of them was just temporary fix for 5-6 months and it started to blow out again ..

Well the problem is because contact surface of the mainfold isn't flat on the two end corners , it haves 2-3mm deep craters from where it blows gases out (you can see that on pictures as black areas on the corners ..) , and i can't seal this surface to make long term gas tight seal with any brand of exhaust mainfold gaskets or high temp. gasket sealants ..

So I'm looking for some tips on how to repair this manfold surface on the corners ?
Can i mill/grind entire mainfold 2-3mm down in order to make fresh flat contact surface ?
Or can i just weld this craters on the two end mainfold corners and then grind this welded area back down to the original contact surface ?
Something else maybe ?

Thanks !!
Damir

pics :

[Kev Rooney]

Welding cast metal is difficult, welding cast metal contaminated with carbon is nigh on impossible. I think you have enough flange thickness to attempt a milling operation although it may be cheaper and simpler to obtain a secondhand replacement ?

[DamirGTI]

Hi !

Well i can't buy/order new exh. mainfold they don't make them no more for this car/engine :( . I can only look for a spare one from breakers , but these cars are also a bit rare here in my country so the secondhand spare parts are also..

How much can i mill down cast iron mainfold ? This one is now 12.5 - 13mm thick .

Thanks !
Damir

[Kev Rooney]

As little as you can get away with really. I'd go for a maximum of 3 mm off. The burn away was probably caused by not dealing with an exhaust blow as soon as it occured. I not sure if Peugeot use brass exhaust nuts ? This is how Ford engines dealt with loossning of the exhaust manifold nuts caused by heat /metal expansion.

[DamirGTI]

Hello !

2mm or maxi 2.5mm will be enough for resurfacing !
The nuts and studs for exhaust manifold on this engine are made from steel , they are not brass nuts/studs .

Thanks a lot for help !!

Kind regards
Damir