Last night I fitted a new decat Magnex centre and found that I had to tighten the bolts extremely tightly before the seal seemed to be air tight between the down pipe and centre section. Can anybody tell me if this is normal or if it should seal fairly easily?
Also, can anybody explain the reason for the type of join used between these sections and the purpose of the spring on the spring bolts as they are now totally compressed after tightening. What advantage do they offer?
Thanks for any replies.

 

The springs are there to give some flexibility in the join, so that if you clout the centre section (on speed bump etc) the join will flex rather than ripping the turbo off!!

When my d/p was fitted, the springs were a bitch to replace (apparently) but still had some play to retain the flexibility.

 

I've loosened the joint slightly now so there's a bit of slack in the springs and it seems ok.

 

The spring bolts are there to allow the downpipe to flex/twist with the engine. As the engine rpm increases, it tries to turn on its mountings. I think it's called torque!

Magnex usually supply replacement (longer) bolts & springs with their centre pipes to make fitting easier since the centre pipe flange design is slightly different.

Dark (Mark)

 

Scoobysnacks.

Are you sure that the conical fibre gasket on the end of the downpipe is either a) there(!) or b) in good condition?

It does sound like there may be an issue with it if your springs are compressing totally.....

Neil.

 

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Neil F:
<B>Scoobysnacks.

Are you sure that the conical fibre gasket on the end of the downpipe is either a) there(!) or b) in good condition?

It does sound like there may be an issue with it if your springs are compressing totally.....

Neil.[/quote]

I fitted an HKS d/pipe to my old uk turbo, retaining the centre cat. The HKS downpipe had a full face flange and my OE centre section had the fitting as described above. Is there a mismatch between the magnex/ OE exhaust?
I had to do some cutting and welding to make the HKS a) flange compatible b) fit the back box on the hangers. At the time I put it down to the HKS either being compatible only with other HKS exhaust sections or for use on Jap import motors. I'm still not sure if the grey imports have a different flange assembly. If this is the case, I would presume that magnex make de cats for both types and you may have the wrong one.
Are there any exhaust Guru's out there who can clear this up?

 

I checked the end of the downpipe again yesterday and as you thought might be the case Neil, there is a gasket on there but it was so dirty I thought it was part of the pipe. I could also see close up that the surface had a brilo pad effect but was worn smooth - does this mean I require a new rougher surfaced one for a better seal?
Thanks for your comments.

 

Should be okay, mine was the same.

When it's all assemblied you can check for leaks by feeling around the outside edge of the joint.

A minor leak will seal itself after a few days driving. The twisting action of the downpipe against the centre section will force the gasket to bed itself in.

If it's still leaking after a week or so then you might need a new gasket. Don't use exhaust sealant, it can find its way inside and will lodge inside the backbox.

Dark (Mark)

 

Thanks Dark (Mark). Just what I wanted to hear.

 

Scoobysnacks.

As Mark says smooth is fine so long as it's not worn too thin (hence the bolts clamping all the way down).
Only other thing I can think of is that the inside of the magnex section isn't perfectly rond or has a lump of something stuck to it which is causing a gap.
Other than that I suppose that it could bed in OK?

Neil.