Catalytic Converter

[hokenmk3]

Hi Golf Gurus:

The catalytic converter in my mk3 golf 2.0 GL rattles like buggery when the the car is cold. I think it is stuffed. I have been using 98 octane fuel for the last year and I think it may have eaten through it. Would this be the case?

To replace it, I like the idea of using a Magnaflow hiflow cat off ebay from Brisbane cause they are only $130. They are available in a number of sizes and I was wondering what size would be best for me to get.

What size is the intake side of the cat? Is it 2 1/4 inch? I think the shop would chop the middle section out of the stock cat and weld in the replacement cat and I would like to get the appropriate size so it is easy for them. Would this fit under the heat shield cause I have read somewhere that the catalytic converter's heat shield is entirely necessary on a mk3 golf 2.0 GL.

Would they have any trouble putting the oxygen sensor in a non-stock cat?

Should I be using 95 octane or 98 octane fuel with the new cat? Will the 98 chew the rhobium catalyst because the car is tuned for 95/96?

Any assistance with this enquiry would be much appreciated!

[MattyT]

... I have been using 98 octane fuel for the last year and I think it may have eaten through it. Would this be the case?

In a word, no. AFAIK, cat's just... die. They live in a pretty noxious environ and only very high EGT's kill em. But I'm no mechanic.

Magnaflow ftw!

The common aftermarket size for golf exhausts is 2.25". NO idea on stock size, sorry.

[Mrk_Mickey]

Stock size is 2.25" actually the better fuel you use the BETTER it will be for your cat mate, it won't have to work as hard crapping out good smoke!

Magnaflow make a proper cat for the mk3 so I think having the oxygen sensor put in should be very simple. You could shoot an email to the seller before you buy if you're a bit worried about it, I'm sure they'll answer your question. I'm not sure about the heat shield but I'd take a guess and say the magnaflow will fit above it cos it looks small!

EDIT: My bad, stock size for the VR6 is 2.25"...someone with a GL will have to tell you your stock size lol.

[Golf Loon]

The ghetto mod is to take yours out and knock all the bits out and fit it back in. Thus making it real free flowing.

Disclaimer : This may be illigal in your state and I am in no way condoning doing this.

You should only use 98 octane, the car will go further and run cleaner, so it ends up costing the same as commodore sluury fuel.

[hokenmk3]

The $130 cat off ebay was 3/4 of an inch wider in the middle than the one recommended by magnaflow. I ended up getting the cat recommended for a VR6 for $155 because it was significantly cheaper than the cat recommended for the 2.0. They only differed by the oxygen sensor port. The cat for the 2.0 already had the port and the cat for the VR6 had no O2 sensor port (yet!) They were both 2 1/4 inch in and out.

Thanks for your assistance gang!!