Problems with inboard diesel (part 2)

[Birvidik_Bob]

Morning chums (well, it’s 8:50 here).

Thanks for all your suggestions on my previous post (& Hi Chris – looking forward to seeing you here). To recap & bring things up to date:

Mermaid melody 4 cylinder 90 HP naturally aspirated engine, 1100 hours since new. Regularly maintained according to manufacturer’s recommended schedule. 11 hours since last service (including oil change, new injector nozzles and tappet adjustment – the last two done by a mechanic in Gouvia).

Ran fine for the first 4 hour run to Mourtos. 5 hours into the run to Lefkas oil pressure began to progressively drop and exhaust began to give out increasing amounts of white smoke.

Now the engine’s cooled down I’ve had a look at things. Oil level much higher than it was. Viscosity difficult to determine, but if pushed I’d say it was thinner. No sign of milkiness or emulsification. Coolant level a little lower but not much. Some signs of oil spray from the fitting for the breather pipe that redirects oil vapour into the air inlet. Small signs of oil leakage from two of the studs holding the rocker box cover down.

Another point, which may or may not be of significance, is that there appear to be small amounts of diesel pooling in the wells in the cylinder head where the injectors are fitted.

So – I’d guess it looks like diesel leaking into the oil, but still three questions:

1) What’s the most likely cause?
2) How would this diagnosis explain the white smoke? There was a large increase in smoke over a few hours.
3) Anyone know of a good diesel engineer in Lefkas?

Thanks again

Bob

 

[oceanpilgrim]

hi
white smoke is normaly to much fuel ,has the cold start fuel stuck in,if fitted ?,would suspect fuel inj pump,but before getting to involved try getting fresh fuel in a can and running the engine on that first,have been sold parafin mix before,change the oil and filter asap,also check the air intake is clear

 

[seamaster30]

if the fuel pump uses a rubber diaphragm and is attached to the block it could have split letting fuel into the engine.

 

[Latestarter1]

Bob,

You have a CAV/Delpi DPS fuel injection pump on the Genisis. Never had problems with the earlier CAV DPA however failure of the DPS front seal is not unknown and will lead to lube dilution as the rotary pump is lubricated by fuel not oil.

Once lube oil contaminated the dramatic loss in viscosity will lead to the symptoms you describe.

Although a pump shop job to replace the seal should not be expensive, about a tenner for the seal and a hours work, however are in the hands of the robdogs. Seal replacement should not requre full pump strip down and recalibration, expect this try on.

Change oil and filters and away you go.

 

[oldharry]

White smoke is either steam from overheating or lack of coolant flow, or is unburnt diesel 'fog' - i.e atomised diesel fuel as it emerges from the injectors, passing through the engine without igniting. This happens when there is insufficient fuel being delivered to the combustion chamber to ignite properly - exactly what would happen if the fuel pump had developed a leak, as Lateboater has suggested. Diesel fog has a very pungent and distinctive smell, and a lungfull does you no good at all! It also occurs if there is insuffient compression or heat to ignite the atomised fuel charge.

Also the lack of viscosity in the lube could result in compression loss as possibly the rings will not be doing their job so well, so reducing compression which would also contribiute to non-ignition of the fuel spray.

Over fuelling results in black smoke, not white, because as the fuel/air ratio increases there is insufficent oxygen to allow the excess fuel to burn properly.

 

[boatmike]

Concur with Old Harry and Lateboater. Most probably leak from Fuel Pump. Would explain white smoke and low oil pressure.

 

[charles_reed]

Spit diaphragm in lift pump or leaking oil-seal on injector pump.

First the more likely.

 

[Heckler]

Suspect also a bad rebuild on the injectors, note the fuel in the injector wells, on the older ford engines as I recall the injectors were inside the oil bearing spaces.
Stu

 

[essexboy]

If thats the Ford based 4 cyl unit, the injectors were indeed inside the rocker cover. Check the leak off pipe from the top of each injector. and also the pipe for cracks.