Half dead cat? 1993 vw polo

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Tue 7 Jun 2005 11:39
Half dead cat? 1993 vw polo - Roberson
Hi all,

About 6 months ago, as far as I can recall, shortly after having a new rear silencer fitted to my '93 Polo, a 'rattle' started to make itself heard. It seemed to be coming from the exhaust system, but where exactly, was hard to pinpoint.

Then, I thought I had found the problem. The next time I was under the car, the centre box was blowing at the weld from the silencer to the pipe. This weld had failed, which allowed the rearmost pipes to twist, letting it hang lower that it should. In turn, this was allowing certain parts to catch the heat shields, which is what I thought was causing the rattle, which was starting to get worse.

But... having that part replaced just over month ago, cured the blow, but not that rattle.

Just to clear up. The clanking is like someone striking a scaffold pole or cast drain pipe with a stick, very quickly. It occurs at low revs, usually when pulling away, or accelerating from low engine speeds (when pulses and 'wobbles' from the engine are most frequent and strong).

As this clanking was still getting worse and starting to annoy, I put the front up on some ramps, in an attempt to a) find it, and b) fettle it.

Once on the ramp, i got my mate to shake the exhaust pipe, at the center. The noise was coming from the front, and seemingly, none of the exhaust system was catching on anything. Getting in closer, it seemed to be coming from within the catalyst. Oh dear!

Is this the sound you would expect from a failing cat? It is the original, fitted 12 years and 105550 miles ago, and according to the Haynes, this is the lifespan of such a part (50000-100000 miles). To me, this sounds like the inner structure has collapsed, which is a symptom of overheating due to excess fuel. This is not an impossibility, since i had a lot of trouble with a failing distributor and poor HT leads.

The question is (finally), what to do? For the past few years, emissions have been borderline on CO, but Lambda and Hydrocarbons are still well within the tolerances. Do I change it now or could it be something else entirely? I was thinking about getting the opinion of my local VAG specialist, but this is all time and money, but just a quick look probably wont cost anything. GSF seem to have the best price at £115 (which is half that of euro car parts)

Any ideas and thoughts?
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Wed 8 Jun 2005 18:26
Half dead cat? 1993 vw polo - Roberson
Just to let you know...

I took the car to my local VAG specialist this afternoon and they confirmed that it was indeed, the catalytic converter which was the source of this clanking.

It might be clanking like a good 'un, but it still passed its emissions test!

Total price? £211 inc part (OEM [Ernst]), fitting and VAT.

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