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SR2 with LH150 combined weight


BODs SR2

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2 hours ago, r-harris said:

R&D Marine are the only ones I can find that provide the coupling. The engine is indeed bolted down securely and there is a lot of vibration. 

So how well is the shaft aligned? We need actual measurements for angular and radial misalignment, especially angular. I don't have the Lister recommendation to hand but typically it is advised that you get the angular misalignment to less than 0.05mm - that's hard and can take a long time.

Any single flexible element coupling like the R&D will still have a maximum angular misalignment they cab handle with typically zero for the radial. Ideally with flexible engine mounts you need  a two element coupling like an Aquadrive, Pythondrive, or long Centaflex (or a pair of correctly aligned universal joints).

I think misaligned shafts are very frequently the cause of vibration complaints. If this is not a steel boat how well fitted are the engine beds.

Is this basic vibration from the engine or is it something resonating so making an annoying noise?

I am far from convinced just fitting flexible mounts on such an engine will make a significant difference and may well not be worth the cost.

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2 hours ago, r-harris said:

R&D Marine are the only ones I can find that provide the coupling. The engine is indeed bolted down securely and there is a lot of vibration. 

Then there is something wrong with the engine. Most likely is uneven combustion - one cylinder is working harder than the other

Richard

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I suppose it depends upon if the how the vibration level compare between in neutral at idle and at revving and the same in gear.

What strikes me is that on the SL4s we sometimes found it impossible to get all the manifold stubs the same temperature on idle so they were definitely suffering different combustion in different cylinders.  They did however even the temperatures out one off tickover. That is despite spending a great deal of care and time over the bump clearances, timing (phasing) the individual injection pumps and setting the rack lengths. I concluded the engines were built to older standards.

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Even so, an engine with a dodgy injector and coked up ports will give quite a bit of vibration

R-harris, are you set up to do the work needed to fit flexible mounts? You'll need to drop the top surface of the engine bearers to fit them in

Richard

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5 hours ago, RLWP said:

Even so, an engine with a dodgy injector and coked up ports will give quite a bit of vibration

R-harris, are you set up to do the work needed to fit flexible mounts? You'll need to drop the top surface of the engine bearers to fit them in

Richard

That was my first thought but if the OP has stout hardwood beds on top of the steel ones then taking the wooden beds off may give enough room.

On the other point, in our case it was after an overhaul with new injectors, pistons, glaze bust etc. but I take your point. I think this may be another case where giving us a lot more info may save the OP a fair amount of money.

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I have just had the top end done. New rings and a new valve. Injectors were tested. It starts fine firing second turnover. The guy who did it seemed to know what he was doing and paid a lot of attention to clearances etc. 

The boat is steel hulled and the engine is bolted to I beams and spaced with what seems like hardwood. The main problem is resonance at certain revs. There are a couple of Rev points where it cancels out. There is also an underlying vibration throughout the range. I need to recheck the shaft alignment when I get time. 

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Flexible mounts may not cure the resonance. I think many boats with soft mounts suffer from it, even four cylinder engines that should be better balanced than a twin. On my Bukh 3 pot I still get some resonance like the cooker pan supports, window hoppers and (before I replaced the hopper foams), and stuff associated with the solid fuel stove and that is despite an Aquadrive and the engine having extra internal balance weights.

Certainly recheck the alignment and take a lot of care to get it as close to spot on as you can.

Edited by Tony Brooks
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Just now, Tony Brooks said:

Flexible mounts may not cure the resonance. I think many boats with soft mounts suffer from it, even four cylinder engines that should be better balanced than a twin.

They certainly do!

Is this vibration better or worse than before thew head work?

Richard

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Difficult to say. The vibration seems not to be noticeably any better at higher revs however it may be smoother cruising on a third throttle but after a while it becomes a little irritating. The work on the engine certainly cured starting issues and smoking. 

Does anyone have the weight info I was asking about  

thanks  

 

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An industrial SR2 weighs 415 lb/189 Kg nett. The SRM manual lists an SR2 as the same weight, which means that doesn't include the front bearer beam or the gearbox

None of the manuals seem to reveal what an LH150 weighs, I guess I could weigh one

I would be checking out the fuel pump settings first, and be aware that this is a two cylinder Lister, not a four cylinder Isuzu - it isn't as refined an engine

Richard

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1 hour ago, r-harris said:

Can we do a deal?

Yes, although I warn you that: 1/. you'll get a better price for a running SR on EBay -  we are usually looking for engines to strip and rebuild and; 2/. you'll be a long way short of the price of a new Isuzu no matter which way you sell it

Richard

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On 11/13/2017 at 07:34, r-harris said:

R&D Marine are the only ones I can find that provide the coupling. The engine is indeed bolted down securely and there is a lot of vibration. 

You might like to look up on the web "Tico packing" it"s a cork like compound that Lister recommended when the SR motors were first introduced

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As the reduction box (if the OP has one) hangs off the back of the box and the rear engine feet are part way along the box while the front mounting cross member (from memory) is right at the front of the engine is there not a fair chance that the OP will need different strength flexible mounts front and back?  Just asking because the Bukh with a dirk great flywheel hung off the front uses different strength flexible mounts.

 

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58 minutes ago, Tony Brooks said:

As the reduction box (if the OP has one) hangs off the back of the box and the rear engine feet are part way along the box while the front mounting cross member (from memory) is right at the front of the engine is there not a fair chance that the OP will need different strength flexible mounts front and back?  Just asking because the Bukh with a dirk great flywheel hung off the front uses different strength flexible mounts.

 

Oh, probably. I've no idea really Tony. There must be hundreds of solid mounted SRs in boats with happy owners

Richard

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2 hours ago, RLWP said:

Oh, probably. I've no idea really Tony. There must be hundreds of solid mounted SRs in boats with happy owners

Richard

I agree, which is why we both seem to feel there's something else that needs attention. I just wanted to warn the OP that the overall weight of the engine may only be part of the info he needs. I can see a lot of money being spent for little gain, especially if the &D coupling he is talking about is the all but semi-rigid plastic thing that is so often used and as far as I can see is designed for boats with a Cutless rubber shaft bearing and a flexible stern gland - not a typical narrowboat..

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41 minutes ago, Tony Brooks said:

I agree, which is why we both seem to feel there's something else that needs attention. I just wanted to warn the OP that the overall weight of the engine may only be part of the info he needs. I can see a lot of money being spent for little gain, especially if the &D coupling he is talking about is the all but semi-rigid plastic thing that is so often used and as far as I can see is designed for boats with a Cutless rubber shaft bearing and a flexible stern gland - not a typical narrowboat..

I replaced the engine mounts on the Isuzu in my last boat and was supplied the wrong ones, even with such a smooth engine I could feel my eyes shaking in my head! 

 It would seem a bit of a gamble to fit some to an engine designed to be solid mounted. 

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