Smokey Exhaust - Why? And how to minimise?

[gav]

Just wondering... as I guess with most older diesels, when I put the engine under a bit of strain I tend to get a bit of black smoke (or a lot if really giving it some welly!).

What's the reason for this, and is there anything I can do to minimise this? I tend to put a bit of engine cleaner in before swapping the oil out.

Cheers,
Gav

[HARD L200]

the black smoke is unburnt diesel and yes older diesels smoke more. it is not burning all the fuel at lower revs cause the pump is adding to much fuel for the amount air entering the engine therefore making it run rich. it can be minimised by making sure the air filter is clean and not resticting air flow. and you can also adjust the injector pump so it governs the amount of fuel.

[gav]

Cheers HARD L200 - great to get a solid explanation! Much appreciated

[sibainmud]

One aspect he has left out, as an engine gets old the piston rings don't seal as well causing blow-by and a lesser amount of compression resulting in less oxygen in the combustion resulting in more unburnt fuel leaving via the exhaust.....phew.

For someone with shyt typing skill that was an effort

Not to mention the wear in the injector tips, resulting in larger droplets of fuel being injected, that the engine finds harder to completely burn.

Cheers,

[TD power]

add more boost

[sibainmud]

^^^^^^^^^^^Yip^^^^^^^^^^^

[Mud Hog]

I found moreys diesel additive helped reduce smoke and runs better on hills.

[TD power]

does it only run better on hills

[HARD L200]

Yea that is one point i missed out on there sibainmud

[Mud Hog]

does it only run better on hills

Yes that's when it's under load smart arse

[Overkill]

I found moreys diesel additive helped reduce smoke and runs better on hills.

Yup, my father swears by that stuff, his Pajero with 380thou on the clock and running morleys gives no smoke, misses it in a tank when filling and he notices the difference including performance....

[gav]

I found moreys diesel additive helped reduce smoke and runs better on hills.

Cheers for the suggestion - I'll give it a go

@sibainmud - Thanks for the extra explanation, much appreciated!

[DDAN]

I second that
MOREYS DIESEL SMOKE KILLER
and MOREYS HEAVY DUTY OIL STABILIZER
is great stuff, I've run it in every 4wd i've had, never had a problem

[gav]

I second that
MOREYS DIESEL SMOKE KILLER
and MOREYS HEAVY DUTY OIL STABILIZER
is great stuff, I've run it in every 4wd i've had, never had a problem

Cheers - I've just ordered some of that smoke killer off Trade Me so I guess I'll find out soon

[gav]

Just thought, had engine problems about a month back - some fuel filter was getting clogged. Apparently there's also a second fuel filter a little deeper in the system that the mechanic informed me he bent some wire to reach in and hook it out as it's not really needed(?). I guess more fuel might be getting through now then making me more aware of the smoke.

It's a 1992 Nissan Safari in case you're wondering

[HARD L200]

ok? as far as i know safaris have 2 identical oil filters, and one fuel filter on the lift pump in the engine bay. and if there is another fuel filter on it would be a mesh in the injector pump or in the tank itself. maybe the mechanic adjusted the fuel governor, which is easily done. also if he just used a piece of wire to pull it out it wouldnt be a paper element fuel filter it would have to be the mesh (gauze) filter in the injector pump. Just MYO.

[gav]

Sounds like he removed the mesh one. Anything I should worry about?

Don't know if it's just my imagination, but black smoke issue seemed to reduce considerably after I did my next oil change!?

[pressy]

hi gav, where in chch are you?

[gav]

hi gav, where in chch are you?

North New Brighton - just updated my profile