Diesel exhausts

[rogerp]

I think I once heard that exhaust systems last longer on a diesel car than the equivalent on a petrol one.

Anyone know if that is true? I believe mention was made that there is less moisture in diesel exhaust.

[m8internet]

Not sure about that one
Usual cause is external corrosion
Internal failure is usually due to hot/cold variances, and in diesel engines this is greater
I can usually get an exhaust to last 4 years / 80K miles

[Readster]

Urban myth has it that a diesel exhaust lasts longer due to less water being generated by engine,
Whether it actually true I wouldn't like to say

[rogerp]

Urban myth it is then. As I said, thats what I'd heard.

Cheers.

[Ste]

It's not really to do with water content of exhaust on it's own.

More to do with the acid compounds produced during the combustion process, eg sulphates, which then reacts with the water vapour and make sulphuric acid which then rots the exhaust from the inside out as well as the normal outside in rust etc.

Your duty cycle plays a huge role in determining how long the exhaust lasts, a long commute means that the whole exhaust gets hot and doesn't allow the sulphuric acid / water mix to condense and start the acid corrosion mentioned above.

I'm still on my original exhaust at 110,000 miles and 5 years old, I consider this normal. I didn't replace the exhaust on my last car either (Vec B diesel) which went to 95K before I sold it and the exhaust was still absolutely fine.

I commute about 70 miles each way to work daily, mainly motorway - which is good for general car sympathy.


The 'myth' that diesel exhausts last longer may be due to the duty cycle 'normally' associated with diesel cars - ie longer journeys more frequently than their petrol equivalents, which is the main reason why people buy diesels in the first place - ie fuel economy for longer distances to off set higher initial costs and other running costs.

HTH (I'm a Professional Engineer working in the automotive world, btw)

[tony050263]

It's not really to do with water content of exhaust on it's own.

More to do with the acid compounds produced during the combustion process, eg sulphates, which then reacts with the water vapour and make sulphuric acid which then rots the exhaust from the inside out as well as the normal outside in rust etc.

Your duty cycle plays a huge role in determining how long the exhaust lasts, a long commute means that the whole exhaust gets hot and doesn't allow the sulphuric acid / water mix to condense and start the acid corrosion mentioned above.

I'm still on my original exhaust at 110,000 miles and 5 years old, I consider this normal. I didn't replace the exhaust on my last car either (Vec B diesel) which went to 95K before I sold it and the exhaust was still absolutely fine.

I commute about 70 miles each way to work daily, mainly motorway - which is good for general car sympathy.


The 'myth' that diesel exhausts last longer may be due to the duty cycle 'normally' associated with diesel cars - ie longer journeys more frequently than their petrol equivalents, which is the main reason why people buy diesels in the first place - ie fuel economy for longer distances to off set higher initial costs and other running costs.

HTH (I'm a Professional Engineer working in the automotive world, btw)

hi there i have a 2.2 sri vectra c and i have the chance of a diesel exhaust system but will it be any good on my 2.2 petrol