Smoke coming out of exhaust on a car
 

Can someone help me settle an argument we're having at work? Whats the difference between White and Blue smoke coming from the exhaust.

Thanks

Edit: Its not my car (thank god), will pass on any info. thanks for all the help.

Re: Smoke coming out of exhaust on a car
 

White smoke, not always too much of a problem, may even be general vapour.
Blue smoke usually indicates that the engine is burning oil......and not in a good way! :(

Re: Smoke coming out of exhaust on a car
 

Yeah my old car had blue smoke on startup, found that my oil level kept getting low. Kept topping it up until i managed to sell it. :cool:

Re: Smoke coming out of exhaust on a car
 

As above.
Blue smoke is often an indication that a piston ring or seal has gone, and soon your car will drink as much oil as it does petrol!

White smoke can normally just be water vapour.
Excess white smoke though, is usually an indication that water or anti-freeze has got in to the cylinders. Headgasket failure. Check of the oil filler cap will show a white gunk around the cap area.

Re: Smoke coming out of exhaust on a car
 

Cheers guys, guy's daughter has major white smoke issues coming from the exhaust when engine is warm. Mechanic said it was excess fuel entering the system and she requires a new ECU, I however disputed this and said the same as you guys. (Not that I really know what I'm talking about :D )

Re: Smoke coming out of exhaust on a car
 

(Not that I really know what I'm talking about :D )[/quote]

That makes two of us. ;)

Re: Smoke coming out of exhaust on a car
 

Sounds like a blown head gasket to me. Is the car also lacking in performance?

Check the coolant (is the level low and is there an oily residue there) and like Gnome said, check the oil filler cap for mayonaise (white gunk)

Excess fuel (if it's a diesel) would be Black smoke (and lots of it) (petrol, I'm not so sure about as I've never dealt with fuel injected petrol engines, but you would get a very strong smell of unburn petrol from the exhaust).

I'd say this garage is trying to rip her off. Take it to another one which you know is reputable.

Re: Smoke coming out of exhaust on a car
 

lots of white smoke? id be looking at Head gasket too.

Re: Smoke coming out of exhaust on a car
 

I'd be looking to sell ASAP. or P/Ex

Re: Smoke coming out of exhaust on a car
 

Indeed... From experience, cars are never the same again after the head has gone... At between £400 & £600 for a repair (at a garage,) they are expensive :!:

Re: Smoke coming out of exhaust on a car
 

...wouldn't be a Rover K series by any chance?

Re: Smoke coming out of exhaust on a car
 

It could be over-fueling.
Are there any sooty marks on the rear of the car?
Are the exhaust pipes very black and sooty?
What colour are the sparkplugs? White, black/wet? (obviously the bit inside the cylinder head.....)

It could be the Lamda sensor (located in the exhaust close to the engine) and it could also be the thermostat. These are connected to the ECU and tell it how to fuel the car. If the thermostat is shot, the ECU is never told that the engine has warmed up, so it continues to fuel it as if it was a cold engine - i.e over fuel. It is very very unlikely to be the ECU that's at fault.

I also agree that the other reasons outlined here should be looked for.

Blue smoke indications are dependent on the exact circumstances that they happen - on over run (changing gear etc) indicates worn valve guides, constant or under acceleration indicates piston rings. Lots of it indicates terminal ending of engine; often with an accompaying bang as a piston exits the engine as a big end gives up. Bless volvo.

Re: Smoke coming out of exhaust on a car
 

Also, if the engine is turbocharged, then the turbo is on its way out.

Re: Smoke coming out of exhaust on a car
 

Umm, its a Fiesta. I havent got a clue about what the exhaust looks like as I posting on behalf of a mates daughter but will get them to have a look. I have spoken to my Uncle whos a mechanic and he said it leaned towards head gasket so will pass on all info.

Thanks for the help guys.... a great source of knowledge as ever :p

Re: Smoke coming out of exhaust on a car
 

Definitly agree with headgasket failure and will be losing coolant, as my car did :( It got really worse on my car when i kept driving it until topping up the coolant became no longer effective.

Over fueling, is a common rip off term. I had trouble starting (my fault really after flattening battery and getting no fuel) and they said ECU, but was not at fault. Just needed a charge and more petrol, needs at least 5 litres in the tank! Garage rip me off and broke my car to bits, sued them for damages

Re: Smoke coming out of exhaust on a car
 

All potential reasons need investigating - the problem with a minority of **** poor mechanics is that they do not know how to fault find, since most of them are taught to repair by replacement without understanding cause and effect.

Everything mentioned so far is a reasonable fault given what we know of the symptoms of course ;)