Sealing Exhaust Manifold

[Guest davidimurray]

As per the title any one reccomend anything to put on the exhaust manifold along with the gaskets to make sure it seals. I've got an annoying misfire and the Lambda is showing lean so wondering if a leak could be the cause.

 

(Full details of my problems here http://www.locostbuilders.co.uk/viewthread.php?tid=189530 )

[richyb66]

If it's a tubular a manifold and the flanges are distorted they you could try doubling up the gaskets so you've got more compressability (not a proper word) to take up any gaps.

 

Other than that, you could use a smear of exhaust assembly paste on either side of the gasket. It's messy and bit cowboy but it should do the job.

[Longboarder]

Careful check of the mating face of the manifold. My RH pinto manifold had the pipes and weld about 0.5mm proud so when bolted up the mating faces of manifold and head were held apart. Very simple to dress down with an angry grinder used gently.

 

Nigel

[Guest mcramsay]

Straight edge across the manifold flange, you will prob find its bent like a banana due to it not being machined after the exhaust runners were welded on. File the flange until it's square. I wouldn't use a grinder, you could end up taking too much off or cutting scores in the flange. I wouldn't use double gaskets either, it's bad practice and will most likely introduce more problems as there are more leak paths. I'm not a fan on using sealing compound on gaskets... Kind of defeats the point. And again introduces other problems. Such as creep and squeezing the joint out rather than compressing it.

[richardm6994]

As said above, it's probably your flanges are distorted and need flattening.

 

Also as correctly pointed out above, it's bad practice to use 2 gaskets as the joint-faces where the two gaskets meet are extremely weak when compressed against each other (due to both faces being soft) and could create a leak path.

 

If you need thicker gaskets to take up bigger undulations in the flangers, use thicker gasket material...not 2 thinner gaskets on top of each other.

[Guest davidimurray]

Thanks everyone. Will have a look and see how it looks. Really annoying as she has run beautifully for the first 300miles and now I just want to go out and play

[Guest davidimurray]

Didn't get chance to play last night as domestic duties got in the way

 

Thinking back I remember dressing the manifold weld back flat, also that each exhaust pipe has it's own flange (not one big one) so I would have though there is less chance of it being 'un square'

[Guest mcramsay]

Check ieach individual flange then. When you weld a pipe on to a flange it will always distort the flange, even when jigged. It will actually be easier on individual flanges as you have less are to file, stick a straight edge on each flange length ways and breadth ways and have a quick check, if you will then see how much the flange has distorted.