Engine smoke

[Graham_Wright]

My BMC 1.5 diesel has now been rebuilt. It has been bored, sleeved and reground all round.
It starts ok in the BMC fashion but the exhaust is smoky. Blue smoke. The injector pressures are correct (135 bar) and the spray patterns look ok (but to my eye).
Possible reasons?

 

[vyv_cox]

Is it fully run in? New bores will leak a little oil for a time.

 

[Graham_Wright]

No, it has less than one hour use. Following recommendations, I am not "mollycoddling" it.

 

[Boater Sam]

Valve guides and new oil seals on rebuild?
What oil is it on?

 

[Ostara24]

It takes a good few hours of run in time to bed everything after a rebuild, particulalry if reboring was involved.

Just monitor it and you should notice it stops after a few weeks.

 

[Graham_Wright]

Valve guides and new oil seals on rebuild?
What oil is it on?

I assume so - sad isn't it? Reputable company I trust.
The smoke is a very pale blue and the running is not very smooth. New nozzles on order although the pressure is per the book and the spray pattern looks good (to me but what do I know?)

 

[Boater Sam]

The correct nozzles for the BMC have an auxillary spray hole to the side of the pintle pin. So there are 2 spray patterns. They are for the Recardo patent precombustion swirl chamber in the head.
The Perkins ones look externally to be the same but do not have the extra hole and are slightly longer in the stem which can break through the top hat heatshield in the head when tightened down.
Very pale blue smoke would suggest a spray problem causing poor combustion, or very retarded injection timing.
The timing can be badly affected by wear in the skew gears driving the injection pump or maladjustment of the pump position.

 

[Graham_Wright]

The correct nozzles for the BMC have an auxillary spray hole to the side of the pintle pin. So there are 2 spray patterns. They are for the Recardo patent precombustion swirl chamber in the head.
The Perkins ones look externally to be the same but do not have the extra hole and are slightly longer in the stem which can break through the top hat heatshield in the head when tightened down.
Very pale blue smoke would suggest a spray problem causing poor combustion, or very retarded injection timing.
The timing can be badly affected by wear in the skew gears driving the injection pump or maladjustment of the pump position.

I believe the injectors are correct and the symptoms are the same when I swap to the injectors from my previous engine. There are two jets from the nozzles but, I suppose, the spray pattern can only be judged subjectively using experience yet to make my acquaintance.
I have ordered a new set of nozzles.
In terms of timing, the precise instruction on positioning the injector pump drive shaft read, "set to 5.00 o'clock".
To an engineer like wot I is, that lacks a little precision. However, there are so few teeth on the skew gear that I think 4.00'clock or 6.00'clock would prevent firing completely.
I have a learned friend who grew up with these engines visiting tomorrow and maybe his experience will serve in terms of which way to nudge the pump.
Thanks for the suggestions.

 

[Graham_Wright]

At the end of a long saga fiddling and swapping, the problem was fixed by swapping the pump for another one.
Having paid £300 for the refurbishment of the (apparently) failed original, it has been returned to the engineer for examination.
Prior to this swap, the smoke was intense although white not blue as previously reported and the engine ran roughly with periodic hiccups.
All now well and back in the boat this weekend.

 

[Boater Sam]

At the end of a long saga fiddling and swapping, the problem was fixed by swapping the pump for another one.
Having paid £300 for the refurbishment of the (apparently) failed original, it has been returned to the engineer for examination.
Prior to this swap, the smoke was intense although white not blue as previously reported and the engine ran roughly with periodic hiccups.
All now well and back in the boat this weekend.

So the diesel shop have involved you in a long and difficult process to correct this engine by dint of their poor workmanship in reconditioning the pump?
I would change my diesel engineer!
I think many of the diesel shops now only understand the modern pumps, the antique units are unknown to them and the original staff who did understand old CAV units are pushing up daisies.

 

[Graham_Wright]

So the diesel shop have involved you in a long and difficult process to correct this engine by dint of their poor workmanship in reconditioning the pump?
I would change my diesel engineer!
I think many of the diesel shops now only understand the modern pumps, the antique units are unknown to them and the original staff who did understand old CAV units are pushing up daisies.

I don't think that is the case. This is a long established business and has kit new and old.
It is still possible it was an incidental cause.
When I receive the pump back, presumably with a successful test, I will try it on the old engine.
Proof of the pudding and all that.

 

[Graham_Wright]

The engineer asked if I had changed anything else when I swapped the pump. I replied No.
However, that was not true. The injector pipes also went with the pump which you may think did not matter.
It seems their main purpose in life is to defeat attempts to turn the pump after slackening the attachment hole bolts.
The old pump pipes, in effect, determined the timing of the pump. Transferred with the pump, they then determined the timing of the new engine.
The engine is back in the boat and, hopefully when reconnected, will run successfully.
I then have to find the courage to swap them back. Bad enough on the bench (due to that bottom bolt) but, on board down the back - erm!

I made an adjuster which give leverage and precision to turning the pump. I'll add a photo in case anyone wants to copy it.