Abf manifold issues

[bigberty101]

Evening fella. Need advise about this particular manifold. Purchased one of these when I done my engine rebuild as my standard one was crack, not for the 10bhp "gain" as quoted haha. The issue I'm having is trying to stop the exhaust from blowing. Where the manifold joins the cat it is continuously blowing, I've tried a variety of gaskets and styles and wondered if anyone has had any similar issues? Any help or advise would be much appreciated!

Joe

[chris_d66]

Have you bought a stainless 4 2 1 manifold from ebay if so the problem is no flex in the down pipe so it is possible for the gasket in the flange moving/crushing under load you may need to make the rear engine mount solid or getting a flexible link welded in the down pipe. A friend of mine damaged the studs on his head and in the end ditched the manifold. My Abf manifold also has cracks but did seal when hot when I re built the engine I welded up the cracks and so far no leaks.

[bigberty101]

I've got a flexi join in the system fella so it's all good that way, item number on eBay is 350438337072 the issue is this has a tapered flange and the parts which the bolts go through Isn't soild to the end of downpipe, so when you tighten it up with a form of gasket, the gasses blow back around the joint towards the engine, does that make any sense? If you look at the picture of the manifold on eBay you will see what I mean

[chris_d66]

When the 2 flanges bolt together against the gasket the taper probably has little clamping force against it if this is happening then it will blow as the pipe and flange expand at different rates (linear expansion) or it has been badly distorted.
option would be to tack weld the manifold flange to the down pipe with it all bolted up then drop the manifold and completely weld around the down pipe to stop the leak. ideally the flexi joint needs to be in the down pipe not behind the cat if you still have one fitted as any movement up and down will be greater further down the pipe.

That's the same pipe my mate had running with no cat, he cut of the flange and clamped the pipes together before ditching the manifold the flexi he used was 5cm after where the flange would of been I know he had big problems with it.

[gasketface]

when i found my abf manifold was cracked i looked high and low but could'nt find one that was'nt cracked,even though many sellers said they were'nt,when asked to look closely on BOTH sides,cracks were found.I even considered buying a new one from VW at around £300.Then i looked at aftermarket one's and realised that a decent one costs £300 upwards.Through research i found that the one you have is more trouble than it's worth sorry.I ended up getting my original one welded up.

[Len]

Ah the joys of exhaust manifolds!!!