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Is a Gardner 4LK a liability in a narrowboat?


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No more of a liability than any other engine really. I've owned Gardner's for well over 30 years now, and the lk is a wonderful engine. PROVIDED, IT'S in good condition, I.e built to the correct running clearances, and properly set up. They can be a right box of frogs if they have been codged up, don't just look at the shiny bits. If you get a good one, you'll love it, there not too big for a 60 foot plus boat, but need to swing a big 24" prop if driving through a reduction box . They have a smaller bore and stroke than the lw series, and can rev to 2100 rpm against the lw at 1700. Bore glazing won't be a problem if you use the right oil, and it shouldn't smoke if the injectors "sprayers" are right. Spares. You won't need any! If it's been done right. You'll never wear it out.   The oil filter is a washable fine gauze, only the fuel filter needs changing and these are readily available. As for rpm , mine drives a heavy, 22 ton 65 foot trad through a 2:1 scg box , 24x19" prop. 400 to 600 rpm on shallow canals, 600 to 900 where you can get a move on. It will go up to 1850 on open water, but becomes uncontrollable. They are definitely an enthusiasts engine, just don't look at a 1935 designed engine with 2017 eyes, things have moved on. It will smoke a bit till it's warmed up a bit, but should be clear after a few minutes. That 2lw crank looks like fatigue failure. Not enough inertia in the revolving mass at idle to iron out the torque reversals. Comes of running too slowly for too long. Shame that, that's one crank ruined, they aren't making any more. 

 

 

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13 hours ago, crossley said:

No more of a liability than any other engine really. I've owned Gardner's for well over 30 years now, and the lk is a wonderful engine. PROVIDED, IT'S in good condition, I.e built to the correct running clearances, and properly set up. They can be a right box of frogs if they have been codged up, don't just look at the shiny bits. If you get a good one, you'll love it, there not too big for a 60 foot plus boat, but need to swing a big 24" prop if driving through a reduction box . They have a smaller bore and stroke than the lw series, and can rev to 2100 rpm against the lw at 1700. Bore glazing won't be a problem if you use the right oil, and it shouldn't smoke if the injectors "sprayers" are right. Spares. You won't need any! If it's been done right. You'll never wear it out.   The oil filter is a washable fine gauze, only the fuel filter needs changing and these are readily available. As for rpm , mine drives a heavy, 22 ton 65 foot trad through a 2:1 scg box , 24x19" prop. 400 to 600 rpm on shallow canals, 600 to 900 where you can get a move on. It will go up to 1850 on open water, but becomes uncontrollable. They are definitely an enthusiasts engine, just don't look at a 1935 designed engine with 2017 eyes, things have moved on. It will smoke a bit till it's warmed up a bit, but should be clear after a few minutes. That 2lw crank looks like fatigue failure. Not enough inertia in the revolving mass at idle to iron out the torque reversals. Comes of running too slowly for too long. Shame that, that's one crank ruined, they aren't making any more. 

 

 

Hi,

This is probably the best answer so far and makes sense, the input on the 2LW crankshaft is interesting and if Gardners indicate 320 rpm is the correct tickover rpm, it's best to stick with it.

Thanks

L.

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I'd suggest that unless your interested in the engine per se, get something modern and supportable. After all you are missing out on 60 years of diesel development having an old engine, like a snapshot from the past. Lk spares are out there, but you have to track them down. The last ones were built in 1968 ish. Check If there are any spares with the vessel, and try to obtain them. Get both the engine manual, and the workshop tools book, read and inwardly digest. They are no more difficult to work on than any other engine, though like most Gardner's, you can't withdraw the pistons up the cylinder bore, the cylinder block is lifted from the crankcase instead. The crankshaft runs in thick wall gunmetal bearings, not thin wall shells in the accepted sense. The bearing areas are massive, and wear very slowly. They do have one unusual feature, that the Cambox and timing Chain are lubricated by surplus oil from the pressure relief valve. In a worn engine at idle the pressure can drop enough to starve these of oil. 37 psi is about right. The sump can corrode, I've broken a couple of badly corroded engines for spares, the alloy used is a magnesium alloy with the trade name Elektron. Most Lk`s had cast iron blocks and heads, though there was a special all aluminium version for private cars, but I think these were to special order and dropped during the war. 

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  • 7 months later...
  • 2 weeks later...
On 14/07/2017 at 01:45, crossley said:

That 2lw crank looks like fatigue failure. Not enough inertia in the revolving mass at idle to iron out the torque reversals.

 

Interesting comment. I'm struggling to grasp what you are saying is going on here. Surely there is a torque reversal in that crank web every time the piston changes direction. And thinking about it, every time the other piston reverses direction too as the flywheel collects energy from or gives it back to the crank. 

I'm inclined to the view that break was caused by the blade coming to a rapid halt and the energy in the flywheel (at the opposite end of the crank from the power take-off) doing the damage. 

But I know little bout this stuff. What do the experts here think? 

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On ‎18‎/‎03‎/‎2018 at 20:36, Mike the Boilerman said:

 

Interesting comment. I'm struggling to grasp what you are saying is going on here. Surely there is a torque reversal in that crank web every time the piston changes direction. And thinking about it, every time the other piston reverses direction too as the flywheel collects energy from or gives it back to the crank. 

I'm inclined to the view that break was caused by the blade coming to a rapid halt and the energy in the flywheel (at the opposite end of the crank from the power take-off) doing the damage. 

But I know little bout this stuff. What do the experts here think? 

Not entirely true, but mostly correct. 

  I would like to see the fracture surface before expressing an opinion on the type of failure.  An overload failure ( MtB's second case) will produce a comnpletely different failure surface to that found on a progressive fatigue fracture ( Crossley's original suggestion).  If it is a fatigue failure (the failure surface looks like a beach as the tide goes out) there will also need to have been an initiation site for the crack, which will be visible when the failure surface is inspected.  From what I can see this might well have started at the intersection between the web and the big end journal. That is a classic place for re-grinding work to leave a score or an inadequate fillet which provides the fatigue initiator.

 

  Anything more certain is beyond engineering estiamtes and experience and into the realm of the WAG.

 

N

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On 3/18/2018 at 20:42, Mike the Boilerman said:

No mention in the blog though of any blade foul, on a brief read.

It would also be interesting to learn which end of the crankshaft was connected to the prop....some connect 'back to front' meaning the flywheel is the last thing to spin/stop in the event of a sudden stop creating tremendous forces on the crankshaft. I have seen Gardners installed this way. 

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9 minutes ago, LEO said:

It would also be interesting to learn which end of the crankshaft was connected to the prop....some connect 'back to front' meaning the flywheel is the last thing to spin/stop in the event of a sudden stop creating tremendous forces on the crankshaft. I have seen Gardners installed this way. 

 

Yes I was imagining the Gardner was installed this way with the flywheel at the front. If installed with power taken from the flywheel end then half my comments make no sense. 

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1 hour ago, BEngo said:

If it is a fatigue failure (the failure surface looks like a beach as the tide goes out) there will also need to have been an initiation site for the crack, which will be visible when the failure surface is inspected.

 

Looking carefully at the photo, the face of the equivalent web opposite the centre main bearing is visible, and has what looks like a straight line ledge in the equivalent place to the break. Could this have been the initiation site? 

Seems unlikely for Gardner to make cranks with a design flaw of that nature though.

 

Edit to add:

That's a numpty comment. That line is the joint where the balance weight is bolted on. Duhhh...

Edited by Mike the Boilerman
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  • 2 months later...

Hi

i have a 58ft boat with a Gardner 4LK, i bought it 3 years ago with very little experience of vintage engines.

i have now run mine for around 350 hrs, it runs very quietly and is very smooth using no oil. It hasnt needed any repairs, all i have had to do is change the oil, fuel filters etc.

It starts on the button and has been a pleasure to own. I havnt even needed to adjust the tappets yet.

It does have a large prop, but ive got used to slipping it into neutral when nessesary.  Once up to temp, it doesnt smoke particularly but i would like an expert to check the injectors sometime.

Quite by chance, i discovered the UK Gardner spares centre is just near where i live in canterbury.

 

 

 

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