black smoke when accelerating
 

Hi all,

I noticed that I get some black smoke from the exhaust when doing a fast acceleration (i.e. burying accelerator to the floor) when:-

1) Joining motorway at 50mph then fast accelerating
2) at say 20mph then fast accelerating

Problem disapears under normal driving speed, acceleration conditions

Any idea what it is?.

Additionally, Is whatever the problem is, covered under warrantee ?


Cheers

cooa99

you don't say what model you have, but im guessing its a diesel, if so this is perfectly normal

sorry, its a 3.0d Auto.
I only just changed the oil 3 weeks ago and it seems black again! i was expecting it to look slightly clear at least

cooa99

Perfectly normal for any diesel - or any petrol come to think of it - when you bury the throttle. you asked the engine for lots of go, but it can only burn so much fuel, the rest is soot and gets chucked out the back. If you lift off just a bit, the smoke will stop.

Sometimes you can get a build up of soot in the exhaust if you're not running the engine very hard and next time you do give it a boot-full of loud pedal it picks up that soot - and throws that at the following motorists too.

Also, your nice clean oil will have picked up all the crud left in the engine so it goes black almost instantly, even with a filter change there's always some detritus left in there. You would have to do several changes to totally flush the engine out in order to get rid all of it from every gallery. It's still a lot better with the slightly black new oil than it was with the old stuff in there though. Hot (warm rather than running temp) changes are supposed to be better at getting rid of it as the oil is thinner.

That definately puts my mind at rest.
Might probably take it in again in next couple of days for another oil + filter change at kwikFit for £50 and use and engine cleaner as well.

beign an automatic. Is it possible to spin the rear wheels, 1 side jacked or both wheels have to be off the floor (and in Neutral gear ?) ?

I agree. Sudden acceleration will give you black smoke. Normal !!!

OT - I am curious about your diesel consumption per 100 liters ? care to share such info.......:D

I do mostly motorway mileage for work so i get about 640miles on a full tank doing 80mph using cruise control.
I also get around £250 weekly tax free mileage allowance from my employer(me) which helps. still comes out of my pocket(via my company) though :(.

The difference between the allowance & petrol cost goes Into a Car savings account. That way I am able to save for car depreciation or maintaining the car but easier said than done.

I only wish hector will raise the mileage allowance in light of current petrol costs & up-comming RoadTax hike

One thing I have noticed is that I seem to get different mileage range depending on which filling station i use i.e Shell/BP/texaco. Can anyone shed light on this or its just my imagination?
whats ur consumption like?

cooa99

change your crank case breather valve,I changed mine and the x5 feels quicker and the black smoke is gone.

Romal

where would the crank case breather be and what does it look like, is it something that you should service too.

I would like to see you drive 640 miles on a full tank before refuelling .
do you mean the range display says RANGE 640 MILES after a fill when you have been cruising motorway .
my V8 says optomistic range after a refuel whilst cruising but always needs refuelling way before I get close to the previously indicated range .
I calculate the actual MPG based on how much fuel I put in against miles covered .