Bulletin Board - Message Catalyst Failure My RV8 has developed the "death rattle" commonly associated with a disintegration of the cat elements within the catalyst unit. However upon investigation I have found that the rattle is, in my cars case, originating from the top cover of the heat shield. This cover was welded to the catalyst unit and the retaining welds have fractured through fatigue allowing the heat shield cover to vibrate. Four small welds are required to restore the unit - much cheaper than having to replace the catalyst so check before passing the job to a garage! Geoff Harris 26 February 2010 @ 12:13 Under topic: RV8   Reply(ies) received for this Message Catalyst Failure Forgive me if I have misunderstood your problem! The heat shield above the cats is quite a separate unit because the heat generated must be physically diverted from the chassis itself via a small air cushion. The cats shouldn't have anything welded onto the top of them. I have heard of the mounting shield fracturing and disintegrating leaving the chassis fully exposed to the enormous heat. The interior carpet then melts!! Peter Garton 26 February 2010 @ 13:57   Catalyst Failure Peter, I was of the same opinion as yourself until I had the problem. Now I have found that we actually have a double air gap. The top of the catalyst unit is constructed with a double plate giving an air gap of about 1cm between the actual catalyst body and the top of the complete unit. Air to ventilate this air gap is admitted via a radial aperture around the exhaust pipe entry to the unit and is similarly exhausted at the rear of the catalyst. The top plate itself is tack welded to the main catalyst body. Obviously this air gap ventilation system will only work whist the vehicle is in motion thus we have the second fibre heat shield bolted between the complete catalyst and the chassis. Geoff Harris 26 February 2010 @ 16:19   Catalyst Failure OK, now I understand your problem! Hope all goes well, Geoff. Peter Garton 26 February 2010 @ 16:29   Catalyst Failure Geoff, I had the same problem, very anoying when at traffic lights etc. I solved it by looping some thin wire around the offending shield, (it fits nicely into the groove) tightend with pliers then snipped close to the shield. I did mine 2 years back, took about 10 mins, it's an invisable fix that cost pennies! Hope this helps. Steve Birmingham 26 February 2010 @ 20:31   Catalyst Failure Thanks Steve, I shall wire it up until I can get a permanent repair done. Geoff Harris 27 February 2010 @ 08:47   Catalyst Failure Today the fractured welds on the catalyst unit top plate have been gouged out and re-welded. The result is no more catalyst death rattle. Owners whose cars develop a rattle from the catalyst unit are recommended to check the weld security of the cat unit top plate before committing themselves to several hundred pounds of expenditure to renew the catalyst unit. The weld security of the top plate can be easily confirmed by hand without even having to jack up the vehicle. Geoff harris 05 March 2010 @ 19:20   Advanced Search Search for all messages for Last 2 Days Last 7 Days Last 14 Days All Messages Search by key word Search by topic V8 RV8 Spares Events MGCC BCV8 General Online auction Include archived messages in search When making a posting do note the system automatically signs off your posting with your name You are welcome to post a message or response It could be a technical query or clarification, a maintenance or spares tip, a report of good service from a V8 specialist, or news of an event of interest to fellow V8 enthusiasts. As we welcome new members, this service is provided on a "free and open to all" basis and is not restricted by password access. Spares adverts Any spares or other items advertised for sale on the V8BB will be removed and posted on the V8 Spares webpage on the V8 website. More V8 Bulletin Board aims to attract good quality postings in terms of content subject matter and accuracy. It is not a chat box so any "grumping or flaring" or other undesirable postings will be moderated at the sole discretion of the V8 Webmaster and V8 Chairman. Periodically the postings are archived to keep the list of postings to a manageable length. Please disclose your name and email address when preparing your posting. V8 Register - MG Car Club   Neither the MG Car Club, the V8 Register or its officers and committee members can accept legal responsibility for any of the statements contained in any posting or postings made on this bulletin board. Any material considered to be undesirable in terms of its nature, content or implication will be moderated as promptly as is reasonably possible. Should any party feel the content or claims in any posting may cause them actual or potential damage, please contact the V8 Webmaster promptly so appropriate action may be taken. V8 Webmaster