Lister SR3 Engine cut out when thottle pulled backwards. How concerned should I be?

[KatHasBrokenHerBoatAgain]

We're cruising along for about 2 hours very happily in the winter sun, then the engine sounds like it needs the throttle to he pushed more forward to get the same amount of power. It sounds like it's going to cut out, so I pushed the throttle forward which kept us going along for a good half hour more, but the smoke coming from the engine is significant (I assume because at this point we're burning through a lot of diesel). I realise with playing around with the throttle that pulling it back even slightly risks cutting out the engine, so we continued on full power until we found an appropriate mooring spot. Pulled back the throttle slightly and the engine did indeed stop.

We've got plenty of diesel, had plenty of oil before setting off, filters were cleaned last week.

We're getting a service in two weeks. Should I hold on until the engine service and just travel short distances until then? 

Or is there anything I can check in the meantime? 

Thank you! 

[magpie patrick]

I had a similar problem several years ago - it was caused by diesel leaking into the oil so that the oil was both thinner and far more plentiful than it should have been. I ended up limping all the way from Aynho to Bath with a daily oil change and a can of easy start (and a song has been written in honour of this achievement!)

 

Check the oil, if you have too much of it....

[David Mack]

56 minutes ago, KatHasBrokenHerBoatAgain said:

We're cruising along for about 2 hours very happily in the winter sun, then the engine sounds like it needs the throttle to he pushed more forward to get the same amount of power.

This could simply be leaves around the prop. Just dropping the revs and engaging reverse gear briefly then going back to fowards may solve the problem (but not if the engine stops).

 

After it has stopped, does the engine restart easily?

[mrsmelly]

Lots of possibilities. If its not leaves my first check would be the prop for something on it.

[Tony Brooks]

Smoke coming from the engine - Is this smoke coming from the exhaust pipe or smoke coming up through the boards or out of the hot air outlet? (assuming an air cooled Lister)

 

Certainly do as David Mack suggest, but if that brings no reprieve (probably temporary until you have to do it again) then I second Magpie Patrick. Check the oil for a diesel smell, being much "thinner" than normal, or creeping up the dipstick. The SRs and SLs are well-known for springing internal fuel leaks.

5 minutes ago, mrsmelly said:

Lots of possibilities. If its not leaves my first check would be the prop for something on it.

 

Agreed, but if it is leaves then they won't be found because they will have floated away.

[magnetman]

Yes it sounds like lube oil dilution. 

 

I had this on my first Boat (Lister SR2) and as I was clueless it ended up getting too high and eventually the engine ran away burning its own diluted lube oil. This was near Rugeley. Mental amount of smoke I stopped it by pushing across the decompressor levers. 

 

Check oil level regularly. If it goes up be suspicious and seek professional help. 

 

 

The point is that as the lube oil becomes diluted it also gets thinner and loses its lubricating qualities so the engine can begin to seize up even if it is still running which will cause it to slow down and possibly also overheat. 

 

 

It might not be this but checking the lube oil level is the first thing. 

[zenataomm]

Yes of course you should always know the level of oil on the dipstick, and be aware that if it's creeping up the level then that's bad and an indicator that fuel may be leaking internally.

However, I noticed that you mention a change of filters a week ago.  I'd also be tempted to check for air in the fuel filter.  Show us a photo of the top of it and we can point out the bleed screws if you don't know them.  I imagine your fuel tank is higher than your engine and don't need a pump (mechanical or electrical) to supply fuel to the engine.

[Arthur Marshall]

It does sound like something on the prop. Did you check it? Oil dilution doesn't usually affect engine revs until the engine seriously overheats, when on my Lister it just stops.

[magnetman]

"...we found an appropriate mooring spot. Pulled back the throttle slightly and the engine did indeed stop."

 

Difficult to moor the the boat with it in gear but yes it does need clarifying. 

 

Also a 'filters were cleaned' could result in all manner of nasty outcomes. 

Extra smoke could easily be fuel starvation as suggested by the zen motorbike man above. 

 

 

The most likely thing here is that the Big End has gone. 

Edited December 17, 2023 by magnetman
accuracy

[RLWP]

14 hours ago, magnetman said:

 

The most likely thing here is that the Big End has gone. 

 

Unlikely

 

Richard

[Tony Brooks]

28 minutes ago, RLWP said:

 

Unlikely

 

Richard

 

My thinking also, but I wasn't sure if it was supposed to be a joke or not, so did not comment. Even if it is a partial seizure, my guess is that it's more likely to be the pistons, rather than the bearings.

[MtB]

15 hours ago, magnetman said:

The most likely thing here is that the Big End has gone. 

 

I reckon it will still be there.

 

Distinguishing between leaves on the blade and a more serious engine fault is easy. Take it out of gear and see if it revs freely without smoke in neutral. If the symptoms persist in neutral then its an engine problem. 

 

 

[Tony Brooks]

6 minutes ago, MtB said:

Distinguishing between leaves on the blade and a more serious engine fault is easy. Take it out of gear and see if it revs freely without smoke in neutral. If the symptoms persist in neutral then its an engine problem. 

 

True, but it might still be something around the prop, rather than just leaves, at least the OP has things to check for now.

 

If it is oil dilution and we are told, we can then advise how to solve it.

[magnetman]

I reckon its seizing up. Pistons. 

 

To clarify 'the big end gone' was a flippant remark. 

 

When this happened to my SR2 it did start to seize up a bit. I imagine this was due to the thin oil.

 

That was in 1994 and as far as I know the engine is still running although could have been replaced I suppose.

 

They are durable units and rated for something like 20,000 hours before major overhaul provided servicing is up to date. 

 

But yes the in gear/out of gear question is the first one which needs answering.

 

the OP said they found a mooring and the engine stopped. This to me says it might be seizing. 

 

I'm sure they will have checked the propeller as thats a fairly basic thing most people would know about. 

[Arthur Marshall]

1 hour ago, magnetman said:

I'm sure they will have checked the propeller as thats a fairly basic thing most people would know about. 

I'm not so sure. I met someone a couple of years back who couldn't understand why she'd lost power and had no reverse. It was a tyre round the prop. She'd had the boat two years and had never opened the weed hatch, had no idea what it was for. The latch was so stiff we had to whack it with a hammer to get it to start turning.

[Tony Brooks]

1 hour ago, Arthur Marshall said:

I'm not so sure. I met someone a couple of years back who couldn't understand why she'd lost power and had no reverse. It was a tyre round the prop. She'd had the boat two years and had never opened the weed hatch, had no idea what it was for. The latch was so stiff we had to whack it with a hammer to get it to start turning.

 

Absolutely correct, you should not assume anything, but usually the details given force a degree of assumption. I not that the OP ha snot yet clarified where this engine smoke is coming from, because if it is the exhaust at full throttle then that is typical of overloading - oversized prop, or a properly fouled prop.