Smoke after idle

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Basically one of the valves was very hard to move in its guide, another had a near enough hole in its centre (excessive pit or burnt through). No valve stem seals present whatsoever.
Got new valves on order, stem seals will be fitted as will new injectors and glow plugs.
I think I took most of the head and ancillaries off with about 3 spanners......
 
There nice easy engines to work on and will stubbornly keep running despite any issues. Mine was running fine with an oval cam follower...

I do get a little smoke after chugging at low steady revs (especially after offroading) but sounds like nothing compared to yours.
 
As well as no valve stem seals present whatsoever, there is also one bolt missing from the rocker arm set up! Don't really want to put it back like that but need to find a bolt from somewhere!
 
This is starting to sound "not good" and hints at some previous BIY maintenance. There's no way one of the rocker pedestal bolts could come out by it's own.
And IIRC, aren't some of them also head bolts ?
 
SimonHobson said:
This is starting to sound "not good" and hints at some previous BIY maintenance. There's no way one of the rocker pedestal bolts could come out by it's own.
And IIRC, aren't some of them also head bolts ?
Click to expand...
I agree.... the head bolts are all good but looks like a bodge job so far! Hopefully my service will make it run much better.
 
Ah, there shouldn't be anything in that hole. The 5 pedestals are all the same - 3 have studs in for the rocker cover nuts, one has a screw in that fixes the rocker shaft in place, and one has an empty hole.
 
SimonHobson said:
Ah, there shouldn't be anything in that hole. The 5 pedestals are all the same - 3 have studs in for the rocker cover nuts, one has a screw in that fixes the rocker shaft in place, and one has an empty hole.
Click to expand...
Nice one. That'll stop me messing around trying to find one now, cheers.
 
All back together now. Sat at idle for over an hour then revved hard. No plumes of wispy smoke but did jet out some grey smoke briefly on blipping themthrottle hard........is this normal? Either way I'm really pleased, runs great and doesn't lay a smokescreen behind it.
 
Basically the diesel process is this : Piston comes up and compresses the air, in the process the air gets hot*. At (hopefully) the right point, the injection system sprays fuel into this hot air - and as long as the air is hot enough*, the fuel will spontaneously combust. The fuel is broken up into tiny droplets, each one burning a bit like a candle flame - the liquid gets hot, evaporates and forms a "shell" of vapour, the vapour mixes with the surrounding air, and in the combustible mixture zone it burns, with the heat from the flame providing heat to keep the evaporation process going.
In the presence of lots of excess air (ie engine at low power), and given sufficient time (ie engine running slowly), the droplets can more or less completely combust.
Change either of these, or both when doing your "drag start" at high power and high revs, then there is little (if any) spare air and limited time for combustion. In this situation, a small "core" of mostly carbon gets left over from each droplet of fuel when the air (and time) runs out - add lots of droplet cores together and you get the grey/black smoke that's so familiar when following a diesel that's just "put the foot down".
So much development work by the engine manufacturers for decades has been on two fronts: getting a finer and finer spray (hence the very high pressure systems common these days) because smaller droplets will burn fully much better; getting a better mix of the fuel mist and cylinder air because the better the mix, the less variation and so less opportunities for fuel to have insufficient air for complete combustion.

It should also be fairly obvious why setting of maximum fuelling is critical. Add too much fuel and there's not enough air to burn it all - so you get lots of smoke. Set it too low and you don't get full power. And if you're struggling to pass the MoT smoke test, a quick fix can often be to turn the fuelling down a bit - which can mask that the injectors are getting a bit worn and not creating as fine/even a spray as they did when new ;)

* This is why starting a diesel can be so hard in cold weather. Compression ratio is critical (many engines have a choice of cylinder head gasket thickness to accommodate manufacturing variations), as is cranking speed (the faster you crank, the less time available for the heat to get absorbed into the cold metal of the engine). And also why most small diesels have heater plugs - basically to provide a hot spot that can initiate combustion when cranking alone doesn't cut it.
 
SimonHobson said:
Basically the diesel process is this : Piston comes up and compresses the air, in the process the air gets hot*. At (hopefully) the right point, the injection system sprays fuel into this hot air - and as long as the air is hot enough*, the fuel will spontaneously combust. The fuel is broken up into tiny droplets, each one burning a bit like a candle flame - the liquid gets hot, evaporates and forms a "shell" of vapour, the vapour mixes with the surrounding air, and in the combustible mixture zone it burns, with the heat from the flame providing heat to keep the evaporation process going.
In the presence of lots of excess air (ie engine at low power), and given sufficient time (ie engine running slowly), the droplets can more or less completely combust.
Change either of these, or both when doing your "drag start" at high power and high revs, then there is little (if any) spare air and limited time for combustion. In this situation, a small "core" of mostly carbon gets left over from each droplet of fuel when the air (and time) runs out - add lots of droplet cores together and you get the grey/black smoke that's so familiar when following a diesel that's just "put the foot down".
So much development work by the engine manufacturers for decades has been on two fronts: getting a finer and finer spray (hence the very high pressure systems common these days) because smaller droplets will burn fully much better; getting a better mix of the fuel mist and cylinder air because the better the mix, the less variation and so less opportunities for fuel to have insufficient air for complete combustion.

It should also be fairly obvious why setting of maximum fuelling is critical. Add too much fuel and there's not enough air to burn it all - so you get lots of smoke. Set it too low and you don't get full power. And if you're struggling to pass the MoT smoke test, a quick fix can often be to turn the fuelling down a bit - which can mask that the injectors are getting a bit worn and not creating as fine/even a spray as they did when new ;)

* This is why starting a diesel can be so hard in cold weather. Compression ratio is critical (many engines have a choice of cylinder head gasket thickness to accommodate manufacturing variations), as is cranking speed (the faster you crank, the less time available for the heat to get absorbed into the cold metal of the engine). And also why most small diesels have heater plugs - basically to provide a hot spot that can initiate combustion when cranking alone doesn't cut it.
Click to expand...
Nice write up, very informative. Cheers
 
I'm pretty sure my lack of valve stem seals were causing the smoke issue. I put in new injectors, new glow plugs, new head gasket, new valves and a valve reset for good measure.
 
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