Aygo manifold gasket

[Tommy Aygo]

Hello all, due to the age of our Aygo and 92k miles, I have replaced the "Mani cat" or catalytic converter. However on refitting the new on, after cleaning the surface as best I could and using a new gasket.

There is still a bit of blow back / leak coming from it as I can smell the fumes. It is probably because the mating service is not level despite my efforts of cleaning.

Does anyone know if I can use exhaust putty or similar to even out any dips when putting the gasket on and then the "Mani cat" so that any gaps are sealed by the putty. 

Hope the above makes sense and would love to read your thoughts.

Thanks.

[steveo3002]

i wouldnt expect exhaust putty to last long 

id suggest cleaning the mating surface fully , and check the new part is flat by offering it up to a steel ruler or something known to be straight 

it should seal okay if clean and straight 

[dartrader1997]

Exhaust putty is'nt recommended pre cat as it can get blown into the cat and knacker it. I remember a while ago advised to use high temp silicon on joints pre cat if needed as it stays in place and won't break up. This might work in your case but it would be best fitting if without if possible, just a thought.

[flash22]

What make is the gasket and did you torque down the nuts to the correct spec ?

Get yourself a proper metal (MLS) gasket, eg. Victor Reinz 71-53506-00 what should be under £15

If it's an aftermarket cat, the manifold maybe warped, especially if it's the lower end of the market

never use sealant on a exhaust manifold

 

[fossyant]

Had to get ours done on a new to us 97k Aygo recently. Son said he hit a pot hole and the cat to manifold weld went.  Needed it fixing ASAP so local garage did it. Evidence of previous welding found.  Had the lot done as the exhaust was crusty. 

 

I assume these 'go' with age and mileage.

[flash22]

18 hours ago, fossyant said:

Had to get ours done on a new to us 97k Aygo recently. Son said he hit a pot hole and the cat to manifold weld went.  Needed it fixing ASAP so local garage did it. Evidence of previous welding found.  Had the lot done as the exhaust was crusty. 

 

I assume these 'go' with age and mileage.

Yes the manifolds rot and crack add-in the heat and it being hit with moisture doesn't help and the Aygo being a city car they are constantly heat cycled (short trips)

this is an extreme example.... (click to enlarge)

[Tommy Aygo]

Thanks to all the replies. I cleaned the surface of the manifold inlet with some carb cleaner and sand paper to get a smoother surface. Changed the gasket to a new metal one as opposed to the one that came with the replacement manicat and all seems good. Although the where the bottom of the manicat sits into the middle exhaust pipe doesn't sit flush despite having the metal wire type insert to close the gap.. Anyhow no fumes, so all good