Diesel Fuel Injection System Help Desk

[bennisiozo]

Sirs, good day po,
i have problems with my nissan bd25 engine. when accelerating it emits white smoke after idling the engine for 5+ minutes.idling is also rough but when at 1000-3000rpm its smooth, at 3000+ rpm engine sometimes misfires and emits gray to black smoke.engine response is compromised.

i recently changed the oil, all filters oil,fuel,air but it did not change.it runs 10km/L city,12km+/L h.w.
there is little clear blow by gas at the oil filler but none at the dipstick tube but it consumes 1 liter of oil per 3000kms+.
what is the correct idle speed for my engine?
is the rate of oil consumption normal?
faulty engine?
faulty injection?
I hope you could help me out, thanks.

hi po sir,

may i share my knowledge regarding your concern?

first thing to concider sir is, ilang km n po ba ang natakbo ng bd25 ninyo? if tama po ang estimate ko mahigit 250K n yan or ilang years na po ang inyong sasakyan. regardless of how you use it po. kasi medyo may katandaan na and ganyang modelo ng nissan engine.

the usual problem of old engines with white smoke are, loose compression. loose compression due to the following:

1. worn and carbon filled valve face and valve seat.
a worn and carbon filled valve face and valve seat causes loose compression which leads to rough idling.

2. leak on cylinderhead gasket
leak cylinderhead gasket usually draws oil or water into the cylinder or combustion chamber that causes white smoke when oil, and gray if water.

3. worn cylinder liner/cylinder wall
4. worn and excessive piston ring and its gap
worn cylinder liner and excessive piston ring gap also leads to rough idling, gray smoke due to loose crompression, not all diesel fuel is burn during compression and combustion.

i recommend personally a general overhaul
replace the ff:

valves
valve seat
valve guide
overhauling gasket set (buy)
cylinder liner
piston rings

you can also replace the connecting rod and main bearing if you want to or not if the mechanic says its still OK.

hope it help. thanks