Exhaust/catalytic Convertor

[Chris_Halford]

Hi Guys,

Been a while since I last posted, but I need some advice with the Exhaust/Catalytic Convertor.

I have spent many hours searching on the tinterweb and I am still no closer to resolving my issue. For the last couple of months I've been getting a rattling sound from underneath, like many describe as a marble in a tin can. Ok, sounds like the Under floor Cat has given up the ghost, no problem, just go and get another and replace.

Now, before I do this, is there actually an Under floor cat on a 2004 MK2 Petrol? And secondly, could it be something like a heat shield that could cause the same sound? I ask as I can find no reference to an Under Floor cat on this model, and trying to find a Toyota part code has proved fruitless. All the cats I have come across are either for the MK1 or Diesel Variants.

I am aware that there is a Cat in the engine itself just after the Manifold, but as the noise comes directly from underneath I (hope) its not this one. If there is a second Cat within the exhaust, can it be removed and if so will it still pass an MOT (due in June)?

I really am confused as to whether I have one or not, or if it can be removed or not? And searching has proved fruitless? I can't believe its this hard to get the info I need, unless of course I need the big beast coming from the Manifold, then I can pick one up anywhere.

Cheers

[redlew]

This should help

http://www.toyotaownersclub.com/forums/topic/153000-new-exhaust-for-rav4-xt-r-5-door-2005-model/

[Chris_Halford]

Thanks redlew, did come across that after posting. Does anyone have the part number for the under floor Catalytic Converter?

Also, again I am in two minds about what is causing the noise as I have found this post as well:

http://www.toyotaownersclub.com/forums/topic/153774-exhaust-heat-shield/?hl=exhaust

I guess I need someone to take a good look to determine what is actually causing this, although in that post it mentions 'Immediately I thought of Penny Washer Davrav........pants.........', that doesn't sound to encouraging?

[gjnorthall]

The secondary cat is part of the centre section of the exhaust - this is a fairly long section that goes from the short front pipe to the back box. Part number is 17420-28350 though I'd need the VIN to double check. The cat could probably be removed and the car would pass the MOT emissions test but a vigilant tester may well fail the car because part of the emissions system has been modified outside the manufacturers spec. I would suspect that the cat is OK - you should be able to check for something loose by giving it a few knocks with the flat of your hand. There are two personal protective shields on the exhaust front / mid section. The clips either side of each shield have a habit of rusting / breaking so that the shield then rattles against the exhaust pipe - a sort of metallic tinkle. Have a good look at these shields - it sometimes isn't obvious that they are loose.

[Chris_Halford]

Thanks for the info. I presume if the cat was at fault, there'd be other signs (poor running, engine light shown), if so then as you say the most obvious cause would then be the heat shields. If it is the heat shield, and they are beyond serviceable use because of rust/breaking, can they be removed altogether, or is this not advisable?

If not advisable, where can I get a replacement heat shield/clips from?

The metallic rattling sound is heard when going through the gears and accelerating, but I noticed it was continuous when in 5th gear and travelling at about 60 - 70 mph. At other speeds it appears to be quieter, but I'm sure I can still hear it, especially when accelerating.

[Chris_Halford]

Just found this post. May have a go myself and see if its the same issue:

http://www.toyotaownersclub.com/forums/topic/110898-heat-shield/

[gjnorthall]

There's confusion about the various heat shields. The post you cite concerns aluminium heat shields which are secured to the floor and not the exhaust - they're designed to shield the floor etc from the exhaust heat. They tend to fall off as the area around the fasteners corrode - they can then sit against the exhaust resulting in rattles. Many owners have dispensed with damaged shields with no apparent problems. It's obviously worth checking that one of the shields hasn't come adrift. The shields that I'm talking about are carbon steel and are attached to the exhaust system in two areas towards the front of the car. They're there to prevent contact with the hot exhaust pipe eg someone working on the underside of the car. In terms of protecting individuals, they're next to useless and I wouldn't be worried by their removal. If they're loose they can be secured by something like an exhaust U clip. It really is a case of checking the cat for loose internals, checking that all exhaust hangers are present and sound then checking the underside thoroughly for anything loose and in particular the various heat shields.