Smoking Yanmar engine

[BartW]

Looking at the pictures it looks like unburnt fuel how many hours on the engines are they running at 3000rpm or 1500rpm do the genny's run for long periods on low load setting you say 4amps at 230v = 1Kw do they just charge battery's?

yes valve play is set at 0.2mm for all valves,

and indeed, its thrue that these genny's have been running most of their lives at 1500rpm and LO LOAD
my 2 curent chargers, are set at 200Amps bulk charging, but in our experience the period of bulk charging is not very long,
don't know real timings, but after genny start, we see on the display that the Victron invertor / chargers switch to absorbtion quite soon....(within 30 minutes or so)

moreover,
the charger on the engine bank only has to recharge the consumbtion from one Stabilising fin, (= not much)

we only use the genny's at anchor, triggered when we need the oven or the dishwasher,
or when the domestic batts SOC < 60%
(cooking is on Gas, and we hardly ever use airco at anker)

we have 2 x 610Ah 24V banks, one for Domestic and one for engines, and each bank drives one electric stab fin. via a 8KwVictron charger / invertor
so peak consumption on the genny is say 2 x 24 x 200 = 10Kw, but for less then 30 minutes,
its mostly much less then 5Kw...
the genny max power is 17Kw

 

[BartW]

Blue smoke indicates oil being burnt. This can happen in the following ways:

• Worn valve guides or seals - This would be my first port of call given the gaps and neglect you were reporting.
• Wear in power assemblies (i.e. cylinders, piston rings, ring grooves) - at 4k hours this by consensus seems unlikely.
• Cylinder glaze - If the engine spends most of it's life ticking over and not coming up to temp this is a potential
• Fuel dilution in the oil (oil thinned out with diesel) - not sure with your engine but I have heard some lift pump seals can wear allowing diesel to leak into the engine. Sticky rings, glazing (bore cross hatching wear) etc. Monitor oil pressure and levels.

I'm afraid that your 2 or 3 first bullet points might all be valid !

so conclusion; don't bother: and use that genny as long as it works,
and budget for a new Genny at some date, and mainly use that one,
giving the added advantage of: less smoke, and less noise

these genny's (2 of the same model and age) are too old todo much more rebuild work on them
one is running with less smoke than the other,
that one I can keep as the backup,
and I could keep the bad one just for spare parts.

 

[BruceK]

Possibly, chasing the rabbit down the hole has always been an expensive past time of mine. However if it is simply valve stem seals it might be worthwhile seeing if you can find a complete head gasket kit. They tend to be relatively cheap in a bundled kit. If so swapping out valve stem seals is not an onerous task given the right tooling which can also be got reasonably cheaply. Best though would be to simply take it to a engineering workshop and have them replace the stem seals for you and lap the valves while there. No need for marine engineer prices unless you want to employ one for fitting and removal of the head and reset of the tappets. End to end the whole job shouldnt be more than a days work. I've done enough in my time to qualify that last statement.
As for the rest, unless they are floating cylinders and you can buy a overhaul set with pistons to pop in things look like a yes, maybe just run it until it becomes end of life. Rebore and rebuilds of old motors seldom makes long term sense to replacing the engine entirely, imo at least.

 

[rafiki_]

Bart, does the engine still smoke when the engine is up to temp? I don’t know the ambient with you there, but cooler ambients will cause the engine to run richer, hence more smoke, If the smoke persists I would be tempted to run a compression test?

 

[AndieMac]

......also another routine, when cold, each genny needs 2 starts attempts.............

Hi Bart
I find even the new-ish gensets when cold need the ignition switch held on for between 1-2 full seconds after ignition to keep firing, if you start them like the main engines or a motor vehicle, they shut down.

 

[vas]

discussing with my mechanic, check with an IR thermometer on the coolant pump housing (where the thermostat lives) the actual temp. Mine is v.low and smokes a bit (55C even after 1h running) will check if there's a thermostat inthere, if not (I suspect not-he's pretty sure there wasn't one in there when he rebuilt the engine) I'll install one, or strangle the seawater supply to make up for it.
He recons at operating temp, engine should be at 65-68C (I think it's still low though...)

cheers

V.