Honda civic mb2 DIY de cat

[Hash1988]

Hi I recently had a Rattle from my original catalytic converter so went to my garage I normally go to he said that it needed to be replaced but I wanted a de cat anyway so I just said let's just turn it into one anyway I did it and the exhaust sounds awesome but there's one thing that bugs me when ever I get to about 4000 revs it makes a weird vibrating noise I thought it was the springs on the bolts for the catalyser but changed the bolts it's not as bad now but still vibrates at 4000 revs also checked the o2 sensor to see if that was loose but that's fine does anyone have any idea as don't have a lot of money to get a new de cat I know it's £40 or something for one but can't afford it thanks in advance for any help.

[simpo]

Did you make your cat into a decat or did you buy a decat?

[KiNK43]

It's cus the metal is thin. Heat wrap the cat real tight. Will sound better.

I've been there done that.

[Hash1988]

Yea I made my cat into a de cat so heat wrapping it tight will stop the vibrations? Never thought of doing that so heat wrap the whole cat?

[Hash1988]

Did you use hose clamps to tighten it?

[KiNK43]

Yes mate. I had same a knocked out cat years back. Sounded like wasp buzzing around inside. Heat wrap helped alot

[Hash1988]

Awesome thanks mate for the help was giving up lol il give that ago

[skymera]

iirc, this is due to high speed turbulence in the cat. It's an open space and the air whooshes around at high speed.

 

Though it could be a loose heat shield or something.

[Hash1988]

What power steering fluid would I need for my mb2?

[Didjeridave]

Scott, I'd certainly query the air turbulence idea for the cause of vibrations at particular frequencies/revs; turbulent flows create broadband noise & would reduce the chance of modal vibration; I'd not expect the air itself to be the driving force of the vibrations, more likely transmitting through the metal itself.

 Check welds, if they're starting to rot, they can make a hell of a racket; rotten, loose heatshield as above is another possibility, but if you've knocked out the inner cat meshes via the outer pipes then it's unlikely you've got it all out. If you've access to a welder, could you cut a panel out of the top side of the middle section of the cat, clear all the mesh out & then weld it back together?  Or if not a welder, use some metal strip (large tin cans), jubilee clips or a riveter & a load of gun gum.  It might sound rather 'scrapheap challenge' but I've put cars & bikes through MOTs with exhausts patched with tin cans.  Actually, my bike went through its last MOT with a combination of whiskers & john smiths, although I enjoyed emptying the latter more

 

Power steering fluid - stick to genuine honda. It's not that pricey, you don't need loads & while other fluids may be fine, mixing different fluids can cause issues.