Lister petter engine burning oil and smoking badly, greenmech 150

[Davidmayo]

A few weeks ago I was using the greenmech chipper and it's suddenly started knocking quite badly and chuffing out loads of oil smoke.

 

So I had the engine out, found an inlet valve was stuck open, and corresponding push rod bent. I replaced the valve and push rod and put back together with new gasket set.

 

With the engine now back installed it starts and runs without knocking and all seems fine (runs with no smoke at all) until you get up to the very high revs where it suddenly just starts chucking out massive clouds of blue smoke.

 

This engine has no oil ways through the head so cannot be head gasket, it is now fitted with new valve stem seals, so by my reckoning I have buggered rings?

 

Any advice or experience with similar issue is appreciated, thanks,

[Richard 1234]

A few weeks ago I was using the greenmech chipper and it's suddenly started knocking quite badly and chuffing out loads of oil smoke.

 

 

 

So I had the engine out, found an inlet valve was stuck open, and corresponding push rod bent. I replaced the valve and push rod and put back together with new gasket set.

 

 

 

With the engine now back installed it starts and runs without knocking and all seems fine (runs with no smoke at all) until you get up to the very high revs where it suddenly just starts chucking out massive clouds of blue smoke.

 

 

 

This engine has no oil ways through the head so cannot be head gasket, it is now fitted with new valve stem seals, so by my reckoning I have buggered rings?

 

 

 

Any advice or experience with similar issue is appreciated, thanks,

 

 

I've got a 23hp mower doing the same thing almost chucking out smoke when high revs/under load. 2 mechanics I know both have looked at it and both think piston rings.

I can't think what else it could be if I'm honest but that's the only place the oil could be getting into the combustion chamber I would think.

I haven't had time to rip into mine yet as it's an engine out job. Will have to wait for winter for me to look at it!

[Breezeblock]

A few weeks ago I was using the greenmech chipper and it's suddenly started knocking quite badly and chuffing out loads of oil smoke.

 

So I had the engine out, found an inlet valve was stuck open, and corresponding push rod bent. I replaced the valve and push rod and put back together with new gasket set.

 

With the engine now back installed it starts and runs without knocking and all seems fine (runs with no smoke at all) until you get up to the very high revs where it suddenly just starts chucking out massive clouds of blue smoke.

 

This engine has no oil ways through the head so cannot be head gasket, it is now fitted with new valve stem seals, so by my reckoning I have buggered rings?

run it under load and see how much crankcase back pressure there is check the breather system as well and its may sound stupid but have a look at the air filter if its restricted it might draw oil vapour from the breather

[PeteB]

I'd look to crankcase breather too. Poor rings would show smoke perpetually as well as poor performance through bad compression.

[Davidmayo]

I searched high and low for some kind of obvious breather, Pete b where do I find it on my lpa3 engine?

 

I continued to remove the piston and ring and piston look to be in very good condition

[Davidmayo]

As far as I can see it has no breather, there is nothing that tees into the intake or air filter at all. Therefor even though the rings may look ok it surely HAS to be them?

[spudulike]

The fact the valve jammed, did it take out the valve guide or did the valve contact the piston crown and crack it? Seems strange the rings would fail at bang on the same time!

 

BTW, I know engines and bugger all about chippers!

[gensetsteve]

Was the new valve a good fit or was it a little slack was the valve guide In the head cracked. I think you may have the lister alpha engine with individual pumps inside the block ? Although the smoke looks blue it could be mistaken for over fueling may be worth checking the pumps are set up correctly and not over fueling at high revs. I assume the air filter is not blocked and the inlet hose not collapsing at high revs. Can u run the engine with oil filler cap removed to check back pressure.

[Davidmayo]

The fact the valve jammed, did it take out the valve guide or did the valve contact the piston crown and crack it? Seems strange the rings would fail at bang on the same time!

 

BTW, I know engines and bugger all about chippers!

 

 

The valve guide stayed put and the piston met with the valve. I cleaned off the piston and couldn't see any damage at all, obviously there was a valve shape in the carbon deposit on top of the piston but no visible damage to the piston.

 

But yes does seem to be a coincidence, I think I will price up a new piston

[Davidmayo]

Was the new valve a good fit or was it a little slack was the valve guide In the head cracked. I think you may have the lister alpha engine with individual pumps inside the block ? Although the smoke looks blue it could be mistaken for over fueling may be worth checking the pumps are set up correctly and not over fueling at high revs. I assume the air filter is not blocked and the inlet hose not collapsing at high revs. Can u run the engine with oil filler cap removed to check back pressure.

 

 

 

Yes it's a 3 cylinder Alpha engine with individual pumps however in pretty positive it's oil, this is a serious amount of smoke all at once when you get up to probably top revs. The intake is all fine as is the filter. As for the valve guide, the guide was not cracker just scored so was replaced.