ok... so here's a couple of questions about the indications given by the exhaust pipe end (on the inside obviously):

How it should look like (color) the end of the exhaust pipe for a gasoline engine working in proper condition ?

What factors modify that color and how ?

for a good engine, nothing but a little terracota like dust (or something that looks like rust) that you can whipe away

for a engine thats using too much gas, soot black

I guess the colour of deposits on the spark plug is a better indicator.

Should it make any difference that I am using it mainly in the city? With lots of traffic lights and low speeds.

Edited 13 September, 201015 yr by masster

Mmaster, I presume you use "unleaded petrol" ("essence sans plombe" in French), rather than fuel with Tetra-Ethyl Lead in it? If so, then the exhaust will always be black. The various whites, greys and browns there were lead salts plating out inside the exhaust.

This link http://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm illustrates how to diagnose a variety of engine faults from the spark plug nose colour.

 

I presume you use "unleaded petrol"

yes, I do.

If so, then the exhaust will always be black. The various whites, greys and browns there were lead salts plating out inside the exhaust.

wow, this is news to me... so the so called catalytic converter on Felicia LX is useless ? I mean that's so Tony seeing the tail pipe look like an old chimney...

This link http://www.verrill.c...gcolorchart.htm illustrates how to diagnose a variety of engine faults from the spark plug nose colour.

very interesting and succint.

"the so called catalytic converter on Felicia LX is useless " - Well no. The colouration was from lead salts, which you don't get any more, and the black is basically soot, which catalytic convertor don't treat. What cats trear is CO -> CO2, NOx -> N2 + O2, and sulphur compounds to S2O (rotten eggs smell).

 

The colouration was from lead salts, which you don't get any more, and the black is basically soot

But you see... the "terracota like dust (or something that looks like rust)" legend is alive and well...

I will look better at modern car tailpipes color and I will post my findings.

yep, they're all black. even for new ones... so I guess another legend is demystified.

 But you see... the "terracota like dust (or something that looks like rust)" legend is alive and well...

I will look better at modern car tailpipes color and I will post my findings.

i dont have a cat and i drive a carb felicia, so my tail pipe "Matches"my plugs most of the time, plus the rain and the puddles washes the soot sometimes