Yanmar 3YM30 Fuel cosnumption and white smoke

[Halo]

Hi All
My 3YM30 is getting through about 1.5 litre / hour at 2600 rpm. This seems to be higher than before
There is also some white smoke or steam in the exhaust
I cannot smell diesel ( in this case and more generally)
I have changed the raw water impellor and there seems to be a decent flow of water.
Engine has 950 hours on the clock
Any thoughts about whehther I have a budding problem and what to check ?
cheers
Martin

 

[Twister_Ken]

Your consumption seems low for the 30 horse. I have a 3YM20 at 150hrs, usually run at about 2500 and I get 1.6 lph driving a 5 tonne boat at about 6kts in smooth water. Maybe you're under-propped?

White smoke is often steam - does it dissipate quickly? If so, it's steam and the implication is that things are running a bit hot. If you've got good water flow in and out maybe the thermostat is opening at too hot a temperature or perhaps the heat exchanger tubes need a clean-out?

 

[FullCircle]

If the engine serial is lower than around 4500, has the heat exchanger been changed under warranty recall?

Is the coolant level OK in the degas bottle?

Is the flow through the inlet strainer looking normal? ( I had a partially blocked inlet last season)

Have you got a water feed to a Tides Marine seal or similar that is taking too much raw water flow before going into cooling system?

Is the engine running up to about 3650-3800 RPM under full load in gear? Are you seeing any differing grey/black/blue smoke then?

1.5ltr at 2400rpm (torque/power curve crossover point) is about right.

 

[Halo]

If the engine serial is lower than around 4500, has the heat exchanger been changed under warranty recall?

Is the coolant level OK in the degas bottle?

Is the flow through the inlet strainer looking normal? ( I had a partially blocked inlet last season)

Have you got a water feed to a Tides Marine seal or similar that is taking too much raw water flow before going into cooling system?

Is the engine running up to about 3650-3800 RPM under full load in gear? Are you seeing any differing grey/black/blue smoke then?

1.5ltr at 2400rpm (torque/power curve crossover point) is about right.

Serial No over 5200 and I took the heat exchanger apart in 2011 and cleaned it out
Coolant level OK
Flow viewed through strainer lid looking Ok
All flow to exhaust
Engine will run at full revs - takes her up to hull speed at an indicated 8 kn - not looked at steam /smoke then but will do next weekend
Thanks re consumption figure
cheers
Martin

 

[vyv_cox]

My 3GM30 has averaged 1.5 litres per hour over the past seven years.

 

[Trundlebug]

The white smoke is most probably steam, as mentioned in a post above.

The increased ambient temperature means the incoming raw water, and therefore outgoing exhaust temp is higher too.

I fitted exhaust temp sensors on our boat and in the recent hot weather (31 degrees ambient air temp) obtained the following readings:

At idle, engines hot, 43 deg C
Running at 1500-1800rpm, engines hot, 34 deg C.

The reason for the higher temp at idle is there is less flow.

But these temps are much higher than normal; for example at Easter the running exhaust temp was 22 degrees C.