Omega Owners Forum

Chat Area => General Car Chat => Topic started by: swordfish on 11 March 2015, 16:51:05

Title: after market cats
Post by: swordfish on 11 March 2015, 16:51:05
 :( :(  why is it that after market cats make a farty trash noise
Title: Re: after market cats
Post by: The Sheriff on 11 March 2015, 17:41:30
Cos they're not genuine GM  ;D
Title: Re: after market cats
Post by: swordfish on 11 March 2015, 19:32:16
i was thinking of adding a small universal silencer just after the cat  :-\ :-\   
Title: Re: after market cats
Post by: The Sheriff on 11 March 2015, 19:35:38
i was thinking of adding a small universal silencer just after the cat  :-\ :-\
Why? Does the sound an omega makes really matter? I would be happy they were doing their job at a reasonable price. But, each to their own  :-\




TOP TIP: Turn the stereo up.  ;D
Title: Re: after market cats
Post by: 05omegav6 on 11 March 2015, 22:16:23
The black beastie has aftermarket cats on and sounds fine... Each to their own I guess :-\

That said, they don't look particularly cheap...
Title: Re: after market cats
Post by: biggriffin on 12 March 2015, 06:52:39
:( :(  why is it that after market cats make a farty trash noise
Check manifold, to down pipe isn't blowing..
Title: Re: after market cats
Post by: Marks DTM Calib on 12 March 2015, 08:42:55
Many reasons.

1) Aftermarket cats are cheap and often single skinned
2) Aftermarket cats have little in the way of CAT surface area an consequently only tend to last 1-2 years  before they fail the emissions test.

My advice is ALWAYS to get good second hand ones or if its the 2.2 and the flexi has failed, weld a new flexi into the genuine part.

The only thing that kills cats is over fuelling or potentially a head gasket failure where large quantities of antifreeze get fired down them.
Title: Re: after market cats
Post by: swordfish on 12 March 2015, 09:00:35
there is no   blowing anywhere i had to replace mine due to one breaking up inside and rattling about  .the aftermarket one is just more raspy  and spoils the car
Title: Re: after market cats
Post by: Marks DTM Calib on 12 March 2015, 09:34:33
there is no   blowing anywhere i had to replace mine due to one breaking up inside and rattling about  .the aftermarket one is just more raspy  and spoils the car

That will be due to the single skin, what does help is putting some exhaust wrap around it or keep an eye out for a good second hand part. Adding a silencer wont help sadly
Title: Re: after market cats
Post by: Diamond Black Geezer on 12 March 2015, 09:49:46
Have to say I repaired mine, needed two new flanges welding on, but try and source good second hand ones where possible.  :)
Title: Re: after market cats
Post by: swordfish on 12 March 2015, 15:19:45
the honeycomb  fell apart in one of mine  not   rotten
Title: Re: after market cats
Post by: Nick W on 12 March 2015, 15:40:52
the honeycomb  fell apart in one of mine  not   rotten


That's what happened to mine. I had to put up with the god-awful rattle until I got back from France.
The replacement was £70 delivered, and sorted the problem: it's quiet, fitted perfectly and there's no difference in the performance. I wish I'd replaced the other cat when I had to do the rest of the system a few months later. I accept that it's unlikely to last as long as the original, but then I don't expect to have the car for another 14 years. And replacement exhausts never seem to last as long as the originals even when they're genuine.

As for used cats? Not on my car; they're likely to be at least 12years old, and are more used-up than used.
Title: Re: after market cats
Post by: Marks DTM Calib on 12 March 2015, 15:48:30
Nick, there is nothing in a cat that is consumable, they will last 30+ years if they don't see certain conditions which will cause them to glaze or overheat.  :y

I would take a 14 year old genuine cat over a pattern one every day of the week  :y
Title: Re: after market cats
Post by: Sir Tigger KC on 12 March 2015, 19:03:55
there is no   blowing anywhere i had to replace mine due to one breaking up inside and rattling about  .the aftermarket one is just more raspy  and spoils the car

Is that what happens when they fail?  ???  As I have a healthy rattle when the engine is hot and ticking over.  :(

I've had a quick look but couldn't see anything loose...  :-\
Title: Re: after market cats
Post by: chrisgixer on 12 March 2015, 19:12:32
there is no   blowing anywhere i had to replace mine due to one breaking up inside and rattling about  .the aftermarket one is just more raspy  and spoils the car

Is that what happens when they fail?  ???  As I have a healthy rattle when the engine is hot and ticking over.  :(

I've had a quick look but couldn't see anything loose...  :-\
Could be numerous things.

Heat shields. On the cat or pre cat. Or the heat should for the lambdas. Opti had one fall off.


Internally could be the pre cat braking up. Or the main cat. But as said, on an oe cat, the innards are unlikely to disintegrate. The efficiency of the cat honey combe coating is what cleans the gases, so as the pre cat is smaller and nearer the cylinders for the same amount of gas the main cats get, it's not surprising they fail/throw pre cat codes etc (Fail, doesn't mean they break up, necessarily. )
Title: Re: after market cats
Post by: Sir Tigger KC on 12 March 2015, 19:49:25
Yes I was thinking a heat shield, but it sounds like something quite substantial rattling.  :-\  I need to have a proper look really.  ::)
Title: Re: after market cats
Post by: ted_one on 12 March 2015, 20:23:35
Well in that case.....if anyone is interested,I have 2 sets of 3.2 cats and 1 set of 3.0 cats,would probably suit someone who is going to relocate their Lambda sensors to eliminate the EML,would give you a chance to do them on a bench at your leisure. No charge/no posting....collection only.Frigg me about and I'll set my missus on you,and anyone who has had a bollicking previously will know it ain't a pleasure.....except for Terbs and Mark who for some weird reason seem to like it :-X :y
Title: Re: after market cats
Post by: omegod on 12 March 2015, 20:26:23
Speaks volumes that a used original Omega cat could have a scrap value of £60-100 due to the precious metal inside but any pattern cat will be worth just £1-2, utter sh*te !
Title: Re: after market cats
Post by: omegod on 12 March 2015, 20:27:03
Well in that case.....if anyone is interested,I have 2 sets of 3.2 cats and 1 set of 3.0 cats,would probably suit someone who is going to relocate their Lambda sensors to eliminate the EML,would give you a chance to do them on a bench at your leisure. No charge/no posting....collection only.Frigg me about and I'll set my missus on you,and anyone who has had a bollicking previously will know it ain't a pleasure.....except for Terbs and Mark who for some weird reason seem to like it :-X :y

Nitro i'm on my way  ;D ;D

Seriously tho ring EMR with the codes off the cats and they'll give you a price for them
Title: Re: after market cats
Post by: the alarming man on 12 March 2015, 20:30:35
Well in that case.....if anyone is interested,I have 2 sets of 3.2 cats and 1 set of 3.0 cats,would probably suit someone who is going to relocate their Lambda sensors to eliminate the EML,would give you a chance to do them on a bench at your leisure. No charge/no posting....collection only.Frigg me about and I'll set my missus on you,and anyone who has had a bollicking previously will know it ain't a pleasure.....except for Terbs and Mark who for some weird reason seem to like it :-X :y



yeah well you know me ken....lol :y

she is a fluffy puss cat...well that is until she learns of the impending monaro then carole will turn into a fire breathing lioness
Title: Re: after market cats
Post by: ted_one on 12 March 2015, 20:33:51
I have tried to get the local scrappy to take these cats which are VX items and they are only interested in diseasal cats,so hence me giving these away.And in all honesty if no one wants them I'll cut them up and take them to the local tip PDQ....not going to hoard stuff that will never get used ::)
Title: Re: after market cats
Post by: omegod on 12 March 2015, 21:01:45
I have tried to get the local scrappy to take these cats which are VX items and they are only interested in diseasal cats,so hence me giving these away.And in all honesty if no one wants them I'll cut them up and take them to the local tip PDQ....not going to hoard stuff that will never get used ::)

 PM'd you Nitro
Title: Re: after market cats
Post by: JamesV6CDX on 12 March 2015, 23:53:41
If omegod doesn't need them, I have a genuine need for some cats, mine are shot. Can collect early next week :y
Title: Re: after market cats
Post by: Marks DTM Calib on 13 March 2015, 08:09:08
Fit the 3.0 ones James... :y
Title: Re: after market cats
Post by: JamesV6CDX on 13 March 2015, 12:17:23
Fit the 3.0 ones James... :y

That's what I'm thinking, and mount the second lambda behind the main cat to ward off the efficiency codes. This would be an excellent upgrade as mine are not in the best shape. I will wait to hear from ken :y
Title: Re: after market cats
Post by: gstylebaby on 13 March 2015, 20:41:36
Can not believe the timing....Was driving home after dropping the boys off and all of a sudden I hear a noise up front think what the  is that.  Get home and part of what looks to be a heat shield has dropped off and scraping on the floor.  How the hell do I sort this out then ??? can you get hold of new parts or is this a new/second hand cat job ???

I add the car still runs o.k just like op has stated its now a bit raspy.
Title: Re: after market cats
Post by: 05omegav6 on 13 March 2015, 21:08:00
Can not believe the timing....Was driving home after dropping the boys off and all of a sudden I hear a noise up front think what the  is that.  Get home and part of what looks to be a heat shield has dropped off and scraping on the floor.  How the hell do I sort this out then ??? can you get hold of new parts or is this a new/second hand cat job ???

I add the car still runs o.k just like op has stated its now a bit raspy.
Large stainless jubilee clips will do the job as a temporary bodge repair :y
Title: Re: after market cats
Post by: gstylebaby on 13 March 2015, 21:32:05
Thanks al. :y
Title: Re: after market cats
Post by: Merlindriver on 17 March 2015, 14:51:52
Speaks volumes that a used original Omega cat could have a scrap value of £60-100 due to the precious metal inside but any pattern cat will be worth just £1-2, utter sh*te !

Blimey, if that's the case I will definitely break my 3.2 rather than trying to sell it or ditch it in one piece to the scrappy.
Title: Re: after market cats
Post by: JamesV6CDX on 17 March 2015, 15:23:00
Speaks volumes that a used original Omega cat could have a scrap value of £60-100 due to the precious metal inside but any pattern cat will be worth just £1-2, utter sh*te !

Blimey, if that's the case I will definitely break my 3.2 rather than trying to sell it or ditch it in one piece to the scrappy.

What's the gearbox like on it? I may also need a cylinder head!!!!
Title: Re: after market cats
Post by: Merlindriver on 17 March 2015, 15:29:00
Gearbox is auto and is fine - needs oil and filters change though. I'd probably like to keep the engine intact though. I expect to lay it up in a couple of weeks.