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DIRECT Dent Repair
21-06-2011, 09:51 AM
Hi all I'm still new to the diesel vehicles.

A few questions if some of you can answer for me would be appreciated.

These D40's tend to blow smoke at low revs, some black and some I've seen white/blue colour.

With the very cold weather we are having I 've seen some blow a small amount of white coloured smoke at start up.

From what I can see these D40's run a little rich down low and I think this contibutes to the smoke.

White smoke is oil burning , unburnt diesel when first started in the morning in cold weather or overfueling?

Black smoke overfueling or not burning fuel correctley?

Manual or automatic is there a big difference?

I'm taking guesses here.

tweak'e
21-06-2011, 10:37 AM
white on cold start up could simply be one dead glow plug or poor injector.
white/blue smoke is most likely turbo leaking oil into he exhaust.

black smoke is unlikely over fueling (unless chipped), more likely to much EGR or fuel not burning well (poor injectors) or simply from crap fuel.

Old.Tony
21-06-2011, 11:01 AM
I couldn't say it better.

If there are clouds of blue smoke there might be a more serious problem, like stuck or worn piston rings, intake valve guide wear/seals ... that's not the sort of damage you'd expect to see in a diesel engine in its early life (<100,000km) unless it was seriously flogged. You haven't indicated the age of this vehicle or how much blue smoke you're seeing.

There might be some visible steam on startup - the combustion process emits several gases but since diesel is a hydrocarbon that is being burnt in air, part of the output is H20 which at normal temperatures you can't see because it's so hot, but at cold temperatures the water molecules coalesce and will be visible as steam.

WoodyD40
21-06-2011, 11:01 AM
mines a manual ... i often blow black smoke when taking off. No chips (yet).

DIRECT Dent Repair
21-06-2011, 12:49 PM
white on cold start up could simply be one dead glow plug or poor injector.
white/blue smoke is most likely turbo leaking oil into he exhaust.

black smoke is unlikely over fueling (unless chipped), more likely to much EGR or fuel not burning well (poor injectors) or simply from crap fuel.

17k on the clock.
No miss on cold start up.
One small puff of white smoke on start up.
3inch,egr mod,chipit module,catch can
No oil usage issues
Runs great
Getting 680plus city from tank and is manual
Caltex vortex fuel

DIRECT Dent Repair
21-06-2011, 01:05 PM
white on cold start up could simply be one dead glow plug or poor injector.
white/blue smoke is most likely turbo leaking oil into he exhaust.

black smoke is unlikely over fueling (unless chipped), more likely to much EGR or fuel not burning well (poor injectors) or simply from crap fuel.

From what I understand if one glow plug is sus then I would have a miss at cold startup.
Injector yes but getting good fuel economy.

If it was turbo then would have constant blue smoke.

burgo
22-06-2011, 01:04 PM
My understanding is the butterfly valve in the intake closes on shutdown, this may intice a little oil into the cylinders ??
Mine used to do it too but not now.
Sounds like your unit is running well so
If it isn't buggered then don't fix it.
Rd's

tweak'e
23-06-2011, 06:27 AM
From what I understand if one glow plug is sus then I would have a miss at cold startup.


not necessarily. my old toyota dropped 3 out of 4 glow plugs before it got hard to start and it never missed on a cold start up.

if you can, test the glow plugs.

turbo leaking oil doesn't always blow blue smoke constantly until the leak is really bad. a small leak is barely noticeable but as it can accumulate in the exhaust after you turn off the engine, when you start up next time it burns it off. however its usually a little bit more than a puff of smoke.

it can still be just crap fuel. i think aussie gets fairly low cetane fuel, lower than what nissan specs call for. simply using a better fuel or a fuel additive may fix all your smoke problems.
to give you some comparison, smokey diesels over here are very rare. i've yet to see ANY d40's blow smoke. the only difference is the fuel.

4.8GU
23-06-2011, 08:17 AM
These things are very sensitive to oil levels in the motor too. Just the slightest bit over the full mark can end up with problems.
They seem to get more into the intake system etc when over full. I am not sure why but

tweak'e
23-06-2011, 09:15 AM
These things are very sensitive to oil levels in the motor too. Just the slightest bit over the full mark can end up with problems.
They seem to get more into the intake system etc when over full. I am not sure why but

crank whips up the oil. closer the oil is to the crank the worse it gets.

DIRECT Dent Repair
08-08-2011, 11:03 AM
Just a follow up on my tailpipe smoke.
Apparentley I had too much oil.
Just had 20k service and no more puff at startup when cold.
These engines a so touchy.