Fiat 500 Exhaust need replacing?

[Alarm Engineer]

Hi,

Just looking at a car for my girlfriend and have seen a fiat 500 she likes. I had a look at it tonight and took a look underneath and noticed the exhaust back box had what looks like black liquid seeping from it. I have attached a picture. Would i be right in thinking this needs replacing? And what would be a fair amount to be knocked off the asking price? Whist on the subject is there anything else i should be looking for with this particular car?

Its a 2008 model with 70k miles

Thank you.

 

[Diver Fred]

OK - none professional eye comments but my thoughts are the black markings are internal corrosion so it needs a new box. But the big question is how is that been caused ?
Is because a gasket (head or manifold) is leaking?
Is it burning oil? That will damage the Cat.
Is it because the car is doing lots of infrequent short runs and so the engine is not reaching operating temprature regularly (if ever)? - Check the colour of the oil and ask how often it has been changed (with Low mileage time is more important than distance!). If the oil is black, has water droplets or feels rough then the engine has a limited life.
Get 1 or more plugs out - see if they are black or oily.
Ask for the service history!
Check MOT for 'Observations' relating to exhust or emissions.

Interweb price of a back box seamingly ranges from £40 to £160 + fitting (say £70). You might be better off pricing for a complete system (including Cat)!

Its the state of the engine that will really guide your offer decision.

 

[Burnerman]

For sure it's a bit moth eaten but par for the course for a car of this age.....so long as there's no real leaks it will pass the MOT and most folks leave it be until it fails.
The black deposit is just soot washed out by the chemical water the engine produces normally.....it's visible because the silencer seams are getting thin.
As for a discount or replacement you can always give it a try! After market exhausts won't last anywhere near as long as a dealer part but will be a fraction of the price.
John

 

[Alarm Engineer]

Brilliant, thank you for your replies!

 

[Brigade77]

It's not just condensation then?

 

[Burnerman]

For every gallon of petrol consumed, the engine produces the same volume of water.....hence the plume of steam when the engine is cold ( or on cool damp days).
When the engine is hot, the vapour plume is invisible.
John

 

[Brigade77]

For every gallon of petrol consumed, the engine produces the same volume of water.....hence the plume of steam when the engine is cold ( or on cool damp days).
When the engine is hot, the vapour plume is invisible.
John

Really?

Where does all that water go then?

 

[Burnerman]

Just straight out into the atmosphere, as a gas. When the exhaust is cold you can see the water dripping out of tail pipes until things warm up.
Bear in mind when fuel burns, it's much hotter than water boiling point so the gases are superheated somewhat.
John

 

[Brigade77]

Just straight out into the atmosphere, as a gas. When the exhaust is cold you can see the water dripping out of tail pipes until things warm up.
Bear in mind when fuel burns, it's much hotter than water boiling point so the gases are superheated somewhat.
John

Water . . . when it's in it's gaseous form is called 'steam'. Steam should never be confused with condensation, which is steam returning to its liquid form.

Whilst I often see water dripping from the end of an exhaust pipe I rarely see it when travelling down a motorway. If all that water (1gall per 1gall) is coming out as steam . . . then where is all the steam going?

 

[Burnerman]

Steam, when superheated, is an invisible gas. If low temperature steam was used in turbines for example, the blades wouldn't last 5 minutes.
Exhaust gas disperses into the atmosphere....after all, a gallon of water produced within say 45 miles isn't a lot.
John

 

[Brigade77]

Steam, when superheated, is an invisible gas. If low temperature steam was used in turbines for example, the blades wouldn't last 5 minutes.
Exhaust gas disperses into the atmosphere....after all, a gallon of water produced within say 45 miles isn't a lot.
John

Yeah but . . . what density of cars do we need on the motorway to start seeing all this water?

The fuel computer on my car shows 9mpg (& I beieve it) when accelerating, if all the cars bunched up on the motorway start accelerating at the same time . . . where is all this water going?

 

[Burnerman]

If you stand at the side of a motorway or whatever, consider the volume of exhaust gases and products of combustion that are heading your way....yet you can't really smell them because they disperse so quickly.
The water vapour is the same. Even HGV diesel fumes - full of particulates we are told - are remarkably pong free considering the volumes that are produced.
John

 

[freddiemercurystwin]

If you stand at the side of a motorway or whatever, consider the volume of exhaust gases and products of combustion that are heading your way....yet you can't really smell them because they disperse so quickly.
The water vapour is the same. Even HGV diesel fumes - full of particulates we are told - are remarkably pong free considering the volumes that are produced.
John

I tell you what, if you go running for example, as I do and are breathing hard, it's astonishing that even when just one car goes past at a modest speed the fumes are very apparent let alone a few cars or just one with his toe down, I regularly run alongside a railway, good lord when an intercity blasts past it actually feels like the air gets thicker.

 

[Burnerman]

An interesting observation Freddie.....I have to admit my sense of smell is minimal ( courtesy of working down a chemical pit at Glaxo's I think). But happily I have no respiratory issues.
John

 

[baldykev]

Cars do produce a lot of water from burning petrol.Thats why the the manufacturer build into there back box a pitot tube which, when exhaust gases flow over this tube it creates a vacuum and draws the water out of the back box.As the back box is far from the engine heat, water will sit there and rot out the exhaust, special doing short journeys
Some after market back boxes do not have the pitot tube in them, thats why they are some times cheaper.