ClioSport.net

Register a free account today to become a member!
Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

Do cat's rattle?



  Octavia vRS tfsi
Do they rattle, meow or purr? ... eh ... sorry gone off on a tangent there ...

I seem to have been getting a rattle between 2500rpm and 2600rpm over the last couple of weeks. I've been under the car a bit and made sure that all relevant parts of the exhaust were secure and not knocking off anything. I've been under the car and made sure that all relevant parts of the heatshield are secure and not rattling, including being head first in over the engine checking all around the manifold.

The only source of a rattle I can seem to find is when I shake the cat. Don't have to shake it particularly hard, just move it about. The car had it's NCT (Irish equiv of MOT) in June and passed so the cat was fine doing it's job on the emissions front at that point.

I'm at a loss at the moment trying to figure out what exactly it is and I'm wondering could it be the first signs of a cat that's on the way out and needs changing?

Car is a ph1 on 93k and on the original cat afaik.

Ian
 
  500 Twinair
The cat could br rattling, unscrew the clamp holding the centrepipe and clamp together and then tighten back up, thats what made mine rattle but the clamp was already tightened, turn out the clamp has rusted away and when it got hot then it loosened up!
 
  BMW E92/Audi S3
refit it. Mine does it. I cant be arsed to sort it out tbh.
The rest of the car rattles so why not let the cat rattle too...
 

Darren S

ClioSport Club Member
Ian,

It could well be the exhaust manifold inserts that bolt the cat onto the front section. The RPM range that you described matches the rattling/ping noise that I had a few weeks back.

Turns out that one side of the insert kit (which is mainly two spring-loaded bolts) had completely sheared through on one end and was flapping about by a few mm. This was the rattling noise that I could hear.

The kit is about £35-£40 iirc and its quite easy to swap out. If it's any help, I'll try to dig out the Reno part number for you - assuming the kit on my 182 is the same as your 172? Might be worth checking that.

D.
 

Christopher

ClioSport Club Member
Manifold-to-cat fitting kit.

It's all one part number. You get a metal gasket, spring-loaded fixings, a clamp and a new gasket for the cat side.

I'm not sure it's the same part number for a 172, i'm unsure if the flange is different, seeing as the manifold is different.
 

Darren S

ClioSport Club Member
Manifold-to-cat fitting kit.

It's all one part number. You get a metal gasket, spring-loaded fixings, a clamp and a new gasket for the cat side.

I'm not sure it's the same part number for a 172, i'm unsure if the flange is different, seeing as the manifold is different.

That be the one. :D

D.
 
i *think* they are the same for the 172 and 182. KTEC offer them at about £20, which is half what Renault are charging at the mo.

it's possible you might be able to get the individual bits from an exhaust specialist - i'm going to take bits of one i've taken off to a local outfit tomorrow to see if anything's available
 
  Nissan 350z
I have the same issue with my Ph1.

Asked my mechanic friend to take a look and he says that aparently cats are filled with some honeycombe/mesh structures that can break and rattle around. Id imagine the only real way to fix this would be to replace it :/
 
  Octavia vRS tfsi
Cheers for the info gents.

Yes, the inside of a cat is essentially a honeycomb mesh. If the cat was on the way out though I'd replace with a high flow sports cat. If it's just the fitting kit that's needed I'll go that route.

Is there any particular way to check if it's the fitting kit that's needed without taking the exhaust apart? It looks like a nightmare of a job to get it off at the manifold end ...
 
it's not easy to get to or inspect; you could try using a handlamp and an inspection mirror before having to dismantle it
 

Darren S

ClioSport Club Member
Cheers for the info gents.

Yes, the inside of a cat is essentially a honeycomb mesh. If the cat was on the way out though I'd replace with a high flow sports cat. If it's just the fitting kit that's needed I'll go that route.

Is there any particular way to check if it's the fitting kit that's needed without taking the exhaust apart? It looks like a nightmare of a job to get it off at the manifold end ...

Ian - have you got just a standard set of car ramps? You'll be able to see/inspect it no worries with the front raised up.

When my 182 was on the ramps, it was pretty obvious that one bolt was shot and it rattled just by tapping it. The biggest issue we had was the fact that the nut on the end of the bolt was properly rusted on. We needed a hacksaw to cut through the bolt in order to seperate it. Once that was out of the way, the other side unscrewed with no issue though.

That enabled the cat to pull away from the front section quite easily.

Hopefully it is the fitment kit that's the problem. It will be a lot cheaper than a cat to replace!

D.
 


Top