Smoking exhaust when under load

[ritmo]

I've had a problem with Betty the BX TZD turbo since I bought her.

When I am accelerating or climbing a hill or any other high load situation I see a cloud of black smoke out the rear view mirror. I would guess that it is unburnt diesel as it doesn't smoke so much if I let off the throttle. Sometimes it's absolutely fine, no smoke even when hammering it (more so when She has warmed up, but sometimes when cold also).

I wonder if the BX maybe has an unburnt fuel sensor, and if so, maybe mine has broken? Or if it completely normal and I just need to get better and controlling it?

I have changed all the filters (apart from the fuel filter, which is planned for the near future). And the oil was changed recently. One point of possible interest is that recently I have been hearing a faint rattle (like a shaking glass jar full off pennies in the distance) on the front offside just as the engine is on 2000rpm. I hope it isn't the turbo packing up. I am hoping that it's the soon replaced driveshaft bearing resonating in it's housing.

Thanks in advance.

[MULLEY]

How much smoke is there? If it seems really excessive such as the cars behind you dissapear in the cloud, then perhaps there might be a problem, if not then it's probably nothing to worry about. I've found that if i drive the car gently, when i eventually boot it, it does clear out the crap in the exhaust that's built up. It does seem to clear after a bit even ragging the car, is this similar to what you are experiencing?

[ritmo]

There's a fair bit of smoke. Doesn't make cars disappear but certainly makes pedestrians run for cover!

She pasted her MOT emissions test well under half the allowable limits and the nice mechanic who tested it didn't look at all surprised when his garage filled with smoke after revving her up.

I've noticed even new diesel cars dump smoke when accelerating hard, but it's not nearly as bad as mine.

Cheers for getting back

[MULLEY]

I'd just keep an eye on it to see if it starts to get worse. I saw a modern alfa diesel 16v thingymagig blow out an amazing black cloud, the chap was really gunning the car but the amount of shit that came out was quite impressive, put my bx quite in the shade/cloud

[kiwi]

You mentioned Turbo! Could be on its last legs or could go on for many more miles.

Glow Plugs? Worth a look

One thing I find about Diesel vehicles is also altitude but then again that will not be an effect in the UK.

[Linegeist]

I think you'll find this is fairly normal.

Diesel isn't the cleanest-burning of fuels, and leaves behind a fluffy black soot very similar to the stuff you find in your chimney after prolonged use (especially if the air filter's clogged). This soot coats everything downstream of the exhaust valves, including the turbo, the exhaust manifold and the exhaust piping, especially if, like me, you pootle around like a geratric slug swimming in molasses.

Once its settled comfortably on a handy surface this soot sits there with no good reason to go anywhere and builds up into a woolly blanket - until you hit the throttle hard and the gas velocities in the exhaust system go into warp drive.

When that happens, and especially if a turbo's fitted and starts spooling up, the engine gets very efficient very quickly (and you get that rather nice 'shove in the back' that the 1.7 engine delivers) and that exhaust system suddenly starts shifting huge amounts of very hot gases.

If you introduced those jolly hot gases down your toilet pan, you'd have the cleanest bog in the land. Same goes for your exhaust. By the time a few hundred cubic feet of roiling, almost incandescent, high-speed exhaust gases have been shoved through the turbo, the downpipe and even the silencer, the poor old soot has been blasted from its various perches and ejected from the tailpipe as a ballooning black cloud. Your exhaust will now be squeaky-clean - and the prat tailgating you will have experienced a momentary total eclipse.

So, the slower you drive, the more soot you'll build up, and therefore eject when you give that ol' motor a handful of right clog. This is why:

• 1. You always give the car a quick thrash before its MOT
  
  2. Modern diesels are having such a problem with their exhaust particulate filters if driven slowly for too long
  
  3. When bored on long drives, you can play WW1 battleships with the traffic following.

Here endeth the sermon.

[MULLEY]

I remember when i was being tailgated by some cabriolet thing with a couple of young girls in it, down a couple of cogs & out comes the smog, they soon backed off rather dramatically (the roof was down at the time )

[mat_fenwick]

I've done the same with agressive tailgaters, although the effect is more pronounced on mine as the max fuelling screw is wound out 'quite a lot'

Any chance of a YouTube video of the smoke to get a better idea whether it's normal or not?

[MULLEY]

I remember having a spin in your car & was impressed by the cloud coming out the back.

[Dollywobbler]

When I had a Pug 306TD, I always took it for an 'Italian tune up' before the MoT as diesels to get sooty if driven gently and then booted. Even my non-turbo BX does this - which I used to great effect with a tailgater this very evening. Don't notice the soot so much in the day, but by night, it's great fun. Stick that in your pollen filters!