Exhaust Issue - Sparks & Smoke

mbunting · Unread post by **mbunting** » 30 Oct 2006, 09:28

Ok, so we collect a P-reg car ( make and model shall remain nameless ) last night, and have a 100 mile return trip.

Said car is a 1.8 diesel ( non turbo ).

90% of the journey back was tootling along about 60 - 70mph, and for the last couple of miles on the motorway, I did an italian tune-up at around 90 for 2-3 miles.

We got off the motorway, and after a few minutes, there was smoke coming from the exhaust - a reasonable amount could be seen in the headlights of my co-driver. She also reported SEEING SPARKS FROM THE EXHAUST.

So we pulled into a layby, to be greated with a grey coloured smoke wafting out of the exhaust - like a fag on tick-over.

The strange thing is, it only seemed to do this on high revs, and in 4th at 30-40 with my foot down, there was no smoke at all.

When we got home ( midnight ), I kept an eye on it for a while - there is a light-grey residue ( like fag-ash ) around the tailpipe, which looks as if it's been on for all of the 60k miles on the car.

My initial thoughts are that the back box has broken up inside, I was thinking a valve, but the sparks from the tailpipe would not be caused by that, surely ?

The car is a Fiesta Mk4 1.8D, and if it's any help, when you take your foot off the accelerator there is a distinct slowdown as if the breaks are binding ( the hubs are cold ).

Any thoughts - I know it's not a french car, but my wife was driving the 406 so that counts

jeremy · Unread post by **jeremy** » 30 Oct 2006, 09:40

You've probably set fire to the crud in the exhaust system - good blast of hot gasses as the engine was heavily loaded for the first time for a long time.

I did this on a Hillman Hunter many years ago. I'd rebuilt the engine after it had been burning an enormous (and I do mean enormous) amount of oil and found broken rings on 2 pistons. Got it going quite well and gradually increased the load on it and one day pulled up after a bit of hardish driving to find the exhaust still smoking happily away on its own. I then drove it gently for a while so it could cool down and there was some airflow round the silencer and all was OK.

I don't think its a valve - it would show up as a very lumpy tickover with white smoke form the unburnt fuel still being injected.

I'd just keep an eye on it for the next few runs - or replace the exhaust!

nick · Unread post by **nick** » 30 Oct 2006, 10:41

Fiestas of that age had a sort of rockwool type wadding stuffed in the back box to reduce noise. This can break up and clog up the exhaust, or even start coming out the tailpipe in great handfulls!
Perhaps if this wadding had been covered in a thick layer of black soot from years of short runs it could be that when you gave it an Italian it finally got hot enough to start burning some of the muck off it? The exhaust being partially clogged with this wadding could also cause a "brake binding" feeling when you lift off the accelerator.

mbunting · Unread post by **mbunting** » 30 Oct 2006, 18:43

Thanks for your replies folks, two people aparently as bonkers as me means that my diagnosis was probably right, so it'll be down to the fast-fit place tomorrow for a new back box ( the tailpipe is a little rusty

)..

Cheers all.
Mat.

Unread post by **504** » 31 Oct 2006, 11:37

I've had this too, years ago on a 205 diesel, didnt do it any harm, just assumed an exhaust baffle had started to break up.

Unread post by **alan s** » 31 Oct 2006, 20:59

I had a similar fireworks display many moons ago in an Austin Lancer. (That's showing my age).

I was coming home from the speedway after competing and it was late night. Still a bit velocitised, I was giving this thing a bit of stick as I was keen to get back home around 25 miles away and the car was one that was owned by the car yard I worked at and was an "ex-little old lady who only drove to church on Sunday" variety. It had about 15,000 on the clock after about 10 years. I noticed an occasional brightness in the rear view mirror that I put down to following cars headlights, until one of the passengers happened to be looking through the back window at the time and screamed "the bloody car's going up in flames!!!"

It seems that I somehow managed to get all the accumulated carbon in the exhaust system to be glowing red hot and each time I backed off, it would suck a pile loose and when I again floored the go pedal, it all shot out the back in a shower of sparks that went about 3 - 4 metres back from the end of the exhaust; very spectacular.
What I wouldn't give to have it now with all these tailgating t0ssers in 4WDs around...it really would be priceless.

Alan S

mbunting · Unread post by **mbunting** » 01 Nov 2006, 12:39

Just a quick update to let you know that the fitter checked out the exhaust - there were no rattles from the cat or the silencer, but the middle section and silencer were quite rusty, so these were replaced. The chap said he couldn't guarantee this would fix it, but after a short bedding in period, some idling time, followed by a thrash revealed the true "performance" of the car ( still slower than an AX 1.5 ! ), and no sparks. ( the air filter does need changing though

)

Cheers
Mat.

James.UK · Unread post by **James.UK** » 03 Nov 2006, 01:50

I had problems with my ZX when I first got it, it was sooo s l o w !! mums pushing prams were passing me on hills

Took the exhuast back box off and it weighed a ton! It was full of what looked like black pitch! Replaced the back box and it was like having two more pistons! The car has been fine ever since.

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