Lister LPWS4 smoking after prolonged idling

[homer2911]

I've been fretting about this for years!  My Lister LPWS4 engine, 1991 build, emits next to no smoke when under load, but blows light blue smoke when idling for any length of time, and clouds of it for a few minutes after being put under load again.  Very embarrassing when moored in one spot for a few days, and running the engine every day for a couple of hours to charge the batteries.  I had a complete top end overhaul about a year or so ago - no real change.  I'm using Morris marine 10-40 oil - would any other oil help the situation?  Should I consider a rebuild, given that these engines have a reputation for smoking anyway?

[Boater Sam]

Smoke after idling is oil down the valve guides, not bores/pistons.

Your top end job was not well done. Either the oil seals on the valve stems are poor or the valve guides are badly worn.

The rubber stem seals can harden and fail to prevent excess oil being sucked down the inlet valve stems.

[Eeyore]

13 hours ago, homer2911 said:

I've been fretting about this for years!  My Lister LPWS4 engine, 1991 build, emits next to no smoke when under load, but blows light blue smoke when idling for any length of time, and clouds of it for a few minutes after being put under load again.  Very embarrassing when moored in one spot for a few days, and running the engine every day for a couple of hours to charge the batteries.  I had a complete top end overhaul about a year or so ago - no real change.  I'm using Morris marine 10-40 oil - would any other oil help the situation?  Should I consider a rebuild, given that these engines have a reputation for smoking anyway?

Are you doing/checking all the usual things to mitigate the issue given the engines reputation?

The obvious ones being to check that the engine reaches full working temperature; is the thermostat the right one and working correctly. The other is to avoid unnecessary idling and to charge batteries with engine at about 1200rpm.

Most of the smoke is likely to be oil carry over in the exhaust "burning" off as the exhaust gas temperature rises with engine load after idling.

 

Edited July 21, 2018 by Eeyore

[Boater Sam]

46 minutes ago, Eeyore said:

 

Most of the smoke is likely to be oil carry over in the exhaust "burning" off as the exhaust gas temperature rises with engine load after idling.

 

There should be no excess oil there in the first place. The oil gets pulled down the valve stems on idle only if the sealing/fit is poor. Blue smoke is oil burning, white is unburnt fuel,

Blue smoke under load is bore and piston ring wear. Black smoke under load is engine overloaded causing poor combustion temperatures.

[Tony Brooks]

1 hour ago, Boater Sam said:

 

There should be no excess oil there in the first place. The oil gets pulled down the valve stems on idle only if the sealing/fit is poor. Blue smoke is oil burning, white is unburnt fuel,

Blue smoke under load is bore and piston ring wear. Black smoke under load is engine overloaded causing poor combustion temperatures.

Going to argue the last part. I agree overloading (or lack of air) but caused by incomplete combustion because of reduced swirl at lower speeds that the fuel being delivered is expecting. I also think overloading can (like with a fouled prop) cause overheating, rather than low combustion temperatures.

[Boater Sam]

The combustion temperature when suddenly overloaded is actually lower due to over fueling and slow burn, continued use in this condition will however lead to engine overheating mainly due to late combustion due to too much fuel and lack of sufficient air for complete combustion, same as over retarding a petrol engine. Also overheats the exhaust system.

[nb Innisfree]

3 hours ago, Boater Sam said:

 

There should be no excess oil there in the first place. The oil gets pulled down the valve stems on idle only if the sealing/fit is poor. Blue smoke is oil burning, white is unburnt fuel,

Blue smoke under load is bore and piston ring wear. Black smoke under load is engine overloaded causing poor combustion temperatures.

I used to own an Audi 100 Turbodiesel, it developed a faulty seal somewhere in the fuel pump which resulted in the fuel pipe to the fuel tank draining overnight. In the morning the engine would misfire and run weak until all air was purged, this was accompanied by blue smoke which stopped immediately the engine started to run properly, no white or black smoke. 

[MtB]

15 minutes ago, nb Innisfree said:

I used to own an Audi 100 Turbodiesel, it developed a faulty seal somewhere in the fuel pump which resulted in the fuel pipe to the fuel tank draining overnight. In the morning the engine would misfire and run weak until all air was purged, this was accompanied by blue smoke which stopped immediately the engine started to run properly, no white or black smoke. 

 

Did you Audi have a Lister LPSW4 engine then??!!