how to change catalytic converter?

[51steve]

Hello Everyone,

I've got a 2000 protege that now has 158k repair free miles on it (ok the camshaft sensor went out last year- do 5 min repairs count?)

The check engine light went off- and the code was for the catalytic converter- verified by the mazda dealer. The haynes manual is useless. How do I remove/replace the converter and the manifold heat shield?

Before doing a repair I always look around to see where problems could arise before I do anything- well the bolts that attach the heat shield to the manifold seem to be the first problem. They are corroded and pitted and the fit is sloppy on the socket. I've been using PB blaster to no avail- and I don't want to shear the bolts off. What do I do?

So as a back up plan, if in fact I do shear off the bolts, I contacted a machine shop to see if the would be able to retap/clean out the threads in the manifold. The shop said that it is often easier to remove the whole manifold from the block with the converter attached and disassemble on the bench. Which, after looking where the five bolts that attach the converter to the manifold seems like it might be the case.

Which brings me back to my question, how do I remove the heat shield and converter?

Also, there are a lot of aftermarket converters. How do these stand up to Original Equipment?

Thanks,

Steve

[hobie237]

Unless a car is an unusual, garage-kept, rust-free example, it can usually be safely assumed that any bolts on the exhaust system will crumble rather than come apart. Thus, I would (and do, whenever I need a converter replaced on such a vehicle) simply cut out the old unit and weld in a replacement. If you can't weld the replacement in yourself, any exhaust shop can do it for you (they can do the cutting, too) and with a generic aftermarket catalyst, the final bill will likely be less than the OEM replacement bolt-in that, um, isn't likely to actually bolt in. Well, it'd bolt in, but the old one won't bolt out.

I don't know what converters cost for Proteges, but I almost always buy generic Magnaflows or whatever is cheapest from the local auto parts store. Just make sure it's a 3-way/OBDII compatible, etc., but as long as it pulls in the parts store's computer as a replacement for your year/make/model, it should be fine as a replacement.