4 into 1 leak and rattle.

[James B.]

I have a 4 into 1 exhaust and where the two sets of four join together, exhaust fumes leak out and they also rattle ☹️ Can anyone tell me if there is a compound (or anything else) that can be used to stop this

 

Thanks, James.

 

 

[Peter R Shaw]

I took mine all apart and put a bit of gum gum around the joints ....also ( for the rattle) I got a long jubilee type clip and bound all four pipes together ..its stailess and looks ok .... stopped the rattle dead !

 

Road7runner S7S.1.7 X flo here

[Bilbo]

They all do that sir

 

Well used Peter's method for years.

 

Still in the end mine became so bad that I resorted to swaging out the downpipes just a little it has helped a lot ... still in my case one had been hammering the other for 13 years when I resorted to this. The gap was say 3 mm all round with inward shoulders on the downpipes. I use Hermetite exhaust paste in a tube and not Gum Gum now seems to last longer. Still blows now and then more related to speed humps.

 

So if its become this bad.......... do not do it unless it has its not for the faint hearted.

 

How to swage it out well my solution...........

 

Buy a cheap socket about 2 mm o/d more than downpipe i/d. Heat downpipe until is near red. Fit the socket onto an old extension bar the WRONG way round hammer socket just a tad at time. Do not bang it in or you will be e-mailing me you can not get the bloody thing out ☹️ Twist as you hit and always make sure its levered free as you go........ yes it is VERY difficult to keep it free.

 

I did have the socket stick in the worst one. Quenched the down pipe and stuck socket the heated again say 6" lower and eventually it came free. Socket less expanded than pipe as it had more mass. As I said not for the faint hearted sill a lot cheaper than new downpipes.

 

Get an assistant to keep the down pipe hot and a bucket of water to cool the socket as it gets hot. Time..... well think it took me well over an hour to do all 4. As you go make sure the 4:1 still fits. If you can tack weld the bar to the socket so much the better. If you can get hold of a tapered solid bar also so much the better

 

End result the last 5mm of the down pipes are wider and snug fit.

 

In the end the less the paste width the less likely it is to blow. It has become a bit harder to fit the 4:1 to the downpipes but its not a job I need to do so often.

 

I now wish I had done it years ago.

 

Oh say 2 years on ones starting to blow again.... but just now and then.

 

For those using heat in a garage always have a fire extinguisher or water hand anyway or if your grinding or disk cutting. Always clear away anything flammable.... you know it makes sense. Never get your 7 near these activities red hot disk or grindings going to make a mess of you nearest and dearest

 

'Can you hear me running' ......... OH YES and its music to my ears 😬 😬 😬

1988 200 bhp, 146 ft lbs, 1700cc Cosworth BD? engineered by Roger King, on Weber's with Brooklands and Clamshell wings, Freestyle Motorsport suspension.

 

Edited by - Bilbo on 22 Apr 2004 22:01:32

[James B.]

Thanks Bilbo and Peter, I decided to give the paste a try and see how we go. I did it this morning (Holts Firegum) and it sounds great at the moment; but how long will it last

 

Cheers, James.

 

 

[Delberts Wallet]

The trouble with firegum is that it set hard and is brittle so it won't last that long. I've been told that B+Q clear silicone sealant is good enough for the job

 

Blue and Carbon 6 Speed Supersport

Bare Bones donut machine here

[Tony Whitley]

I was thinking of cutting a slot in the end of the 4 pipes in the 4 to 1 and fitting jubilee clips to each - compressing the outer pipe rather than expanding the inner. Anyone done something similar / can see a reason for not doing that

 

M1 7 SMW Caterham Elise Mem.No. 10376

[James B.]

Is a leak in the exhaust (at the 4 into 4 joint) detrimental as regards bhp 🤔

 

 

[James B.]

Gareth, you can't be serious about the silicone sealant, can you 🤔

 

 

[Slomove]

I tried various silicones including the high temp copper variety. Did not last long. I think the problem is the soot film that prevented the silicone from sticking and after short time it just blew out. I did not try the hardening stuff because I wanted to be able to remove when needed.

 

here is my solution: fiberglass woven "tadpole" tape cut to length around the header. The glass tape is then wrapped in adhesive aluminum flue tape (to prevent fraying) and tightend/held in place with hose clamps. Normal thick fiberglass tape would probably work but the tadpole cross-section tape helps even out the diameter step. After an hour drive the clamps needed tightening but otherwise it seals very well for the last few months.

 

One problem: it only works if you have at least 1/4" clearance between the header tubes at the joint. Otherwise you can't wrap the glass tape and hose clamps around.

 

Gert

 

 

 

Edited by - Slomove on 25 Apr 2004 01:47:06