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Markinaboat

Anyone have a 2LW with hydraulic drive & bowthruster?

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Am in the process of buying another boat (yes I know!) with a 2LW. The engine has 8500 hrs on the clock but most likely done close to 10,000 as the clock was retrofitted. Drive is ARS hydraulic with bowthruster, a system I like (headroom) as have had two before.

 

Had engine and drivetrain survey done (by one of the most knowledgeable in my book) and as was expected (over pressure in crankcase, oil everywhere, water leaks etc),  a full top end rebuild is required for around £4k to bring her back to her former glory - this in itself is not a problem as had budgeted in with the offer. However, the thruster when operated for more than 3/4 seconds is taking the engine down to around 300rpm, possibly less (tick-over on this one is set to 450) and could even stall. This was tested in neutral at max revs (was pulling 1260 rpm in neutral and 960 with prop engaged). The thruster is turning/working without (I believe) any unusual noises (not much noise with hydraulic of course) and it has us stumped. 

 

Has anyone had a similar experience with a 2LW or indeed any engine? FYI, my previous hydraulic experience has been with a 3LW and JD3 with massive thruster power when required (mainly to get the boat alongside in heavy winds with a failing/failed back).

 

No anti-thruster boring quips please, unless particularity witty or humorous! 🤡

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We have Nanni Hydraulic drive together with Hydraulic Bow and stern thruster. We went through a period when we found a skim of oil in the engine compartment with a small loss of power, but we couldn't detect any obvious leak. It took a number of weeks of frequent use, and many checks around the engine compartment by us and also by marina engineers before a microscopic pin hole was found on a delivery pipe which was tucked away in a location which was difficult to reach. This had been spraying  hydraulic oil but 3was so small that it was very difficult to see. Changing the pipe resulted in an immediate return to normal as you would expect. It may be worth just double checking for a similar issue.

 

Howard

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9 minutes ago, howardang said:

We have Nanni Hydraulic drive together with Hydraulic Bow and stern thruster. We went through a period when we found a skim of oil in the engine compartment with a small loss of power, but we couldn't detect any obvious leak. It took a number of weeks of frequent use, and many checks around the engine compartment by us and also by marina engineers before a microscopic pin hole was found on a delivery pipe which was tucked away in a location which was difficult to reach. This had been spraying  hydraulic oil but 3was so small that it was very difficult to see. Changing the pipe resulted in an immediate return to normal as you would expect. It may be worth just double checking for a similar issue.

 

Howard

Interesting. Did you notice the oil level dropping before you sussed it? Even with a hydraulic leak, the pump will only work to a pre-set maximum pressure (I think?) and of course has a PRV for any over-pressure at the (thruster) drive unit. Can't see how this would put such a load on the engine as an even greater load is exerted from the prop without pulling the revs down so significantly.

 

I'll be calling ARS tomorrow to get their take on it. IT may of course be just a poor match of hydraulic pipe size and/or too powerful a thruster model (8 bhp/75 kgf from a previous sales blurb) although the boat's been chugging away since it's launch in 1998. Valve clearances, timing chain etc have not been checked for a very long time apparently so requires a fair amount of TLC & ££'s but worth it.

 

Edited by Markinaboat
ommission

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31 minutes ago, Markinaboat said:

Interesting. Did you notice the oil level dropping before you sussed it? Even with a hydraulic leak, the pump will only work to a pre-set maximum pressure (I think?) and of course has a PRV for any over-pressure at the (thruster) drive unit. Can't see how this would put such a load on the engine as an even greater load is exerted from the prop without pulling the revs down so significantly.

 

I'll be calling ARS tomorrow to get their take on it. IT may of course be just a poor match of hydraulic pipe size and/or too powerful a thruster model (8 bhp/75 kgf from a previous sales blurb) although the boat's been chugging away since it's launch in 1998. Valve clearances, timing chain etc have not been checked for a very long time apparently so requires a fair amount of TLC & ££'s but worth it.

 

The complication is that this is on a share boat so there was a range of technical aptitude which masked things. It did show up in the sight glass but despite reminders, there were some who thought a small reduction in level was to be expected and just topped the tak back to the correct level! 

 

 

 

Howard

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Hi I have the same engine and bow thruster in my boat and have had the same problem, found it was the alternator a 75amp 24v when batterys bit low if you used the bow thruster at tick over revs dropped well down, the engine just has not got enough power at low revs to power prop. alternator and bowthuster a smaller pulley on alternator helped a bit

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45 minutes ago, Mickj said:

Hi I have the same engine and bow thruster in my boat and have had the same problem, found it was the alternator a 75amp 24v when batterys bit low if you used the bow thruster at tick over revs dropped well down, the engine just has not got enough power at low revs to power prop. alternator and bowthuster a smaller pulley on alternator helped a bit

 

Hi, as I read it the OP's bowthruster is hydraulic.

 

 

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Are you sure  the thruster prop is not fouled. One possibility is it stops turning so the hydraulic pressure rises until the PRV opens. This would load the engine well. No direct experience but had similar on hydraulic hire boats a few times.

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Hi, as I read it the OP's bowthruster is hydraulic.

 

So is mine should have said that i guess

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9 hours ago, howardang said:

The complication is that this is on a share boat so there was a range of technical aptitude which masked things. It did show up in the sight glass but despite reminders, there were some who thought a small reduction in level was to be expected and just topped the tak back to the correct level! 

 

 

 

Howard

Well on the positive side, at least they kept the level up!

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5 hours ago, Mickj said:

Hi I have the same engine and bow thruster in my boat and have had the same problem, found it was the alternator a 75amp 24v when batterys bit low if you used the bow thruster at tick over revs dropped well down, the engine just has not got enough power at low revs to power prop. alternator and bowthuster a smaller pulley on alternator helped a bit

Also has a Leece Neville 24v 110amp although the batts were fully charged having been on float and this was after the engine had been warmed up at full revs in gear for an hour so I would have thought that the alternator wouldn't have been loading too much? Also, this was happening at full revs 1260rpm in neutral!

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I also had a problem with the bowthruster when first fitted the rubber inside was the wrong one it would work sometimes but labored the engine at any revs had to have a replacement after lots of hassle with ARS 

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Something is absorbing the power output of a 2LW.  That something is going to get hot, quickly.  Look for that and you have found where the power is going.  An IR thermometer may be a help for hard to get at to feel stuff.

 

N

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Just a thought  about a possible diagnostic test.

 

If you force the problem to occur in neutral and then put it in gear if the rives rise again you could surmise that the drive motor has provided an alternative path for the hydraulic oil so the pressure in the system drops.

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11 minutes ago, BEngo said:

Something is absorbing the power output of a 2LW.  That something is going to get hot, quickly.  Look for that and you have found where the power is going.  An IR thermometer may be a help for hard to get at to feel stuff.

 

N

Good idea, am not sure Charles had the time for that as his focus was of course on the engine. I'm hoping to be able to to the boat again before the hull inspection on 11th so could take my IR gun with. Locating the relief valve may be difficult though as no idea what it would look like amongst the various components.

9 minutes ago, Tony Brooks said:

Just a thought  about a possible diagnostic test.

 

If you force the problem to occur in neutral and then put it in gear if the rives rise again you could surmise that the drive motor has provided an alternative path for the hydraulic oil so the pressure in the system drops.

Thanks Tony, good point. Apparently it was happening both when in gear and neutral. I know from experience that to expect a good blast from the thruster whilst driving the prop (unless at full chat) is asking a lot.

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1 hour ago, Markinaboat said:

Good idea, am not sure Charles had the time for that as his focus was of course on the engine. I'm hoping to be able to to the boat again before the hull inspection on 11th so could take my IR gun with. Locating the relief valve may be difficult though as no idea what it would look like amongst the various components.

Thanks Tony, good point. Apparently it was happening both when in gear and neutral. I know from experience that to expect a good blast from the thruster whilst driving the prop (unless at full chat) is asking a lot.

It could well be inside the reservoir or part of the control valve assembly. If its external it will have just two connections, one Teed into the main pump outlet  and the other into the reservoir. My guess would be its part of the control valve. 

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26 minutes ago, Tony Brooks said:

It could well be inside the reservoir or part of the control valve assembly. If its external it will have just two connections, one Teed into the main pump outlet  and the other into the reservoir. My guess would be its part of the control valve. 

Thanks Tony. Will look on my current boat first as same system.

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I don't think its a PRV fault because as long as the thruster was running there would be oil flow. I also don't think its a leak because that could not load the engine until all the oil was expelled and the pump seized up. It sounds much more like something stopping oil flow so that could be the motor not turning for some reason, a maladjusted valve, be it for the propulsion or the thruster, or something blocking a pipe. I can't really think the following is likely because of the pressures but I am wondering about the hoses  to the bow thruster. On wet exhaust hoses if the inner skin burns through it can form a sort of vale affair that gets pushed across the bore under high speeds, this can stop the raw water pump pumping so it might be the same on a hydraulic hose except it would load the engine and open the PRV.

 

 

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4 minutes ago, Tony Brooks said:

I don't think its a PRV fault because as long as the thruster was running there would be oil flow. I also don't think its a leak because that could not load the engine until all the oil was expelled and the pump seized up. It sounds much more like something stopping oil flow so that could be the motor not turning for some reason, a maladjusted valve, be it for the propulsion or the thruster, or something blocking a pipe. I can't really think the following is likely because of the pressures but I am wondering about the hoses  to the bow thruster. On wet exhaust hoses if the inner skin burns through it can form a sort of vale affair that gets pushed across the bore under high speeds, this can stop the raw water pump pumping so it might be the same on a hydraulic hose except it would load the engine and open the PRV.

 

 

It is somewhat confusing. Needs a hydraulic specialist with the correct kit to test all areas. Long chat with ARS this morning and they said if the PRV was malfunctioning (which they can do apparently) then the back pressure so to speak would of course load against the engine. They also said the drive unit on the thruster could have a similar effect although I don;t see why the PRV would not then balance this out, unless of course both have gone!

 

I'm hoping to be able to get to the boat again and test it myself, away from the pontoon and see how well it works or not. Need to find a hydraulics expert that isn't light years away or OTT with the ££'s. At the end of the day, I'd be spending the best part of £4k for a full top end rebuild of the 2LW and another £3k in other areas so really can't manage upto perhaps £3k to get the thruster issues sorted as well. If all working as it should be, the boat would be worth maybe £68k but at this rate, it would've cost me  £73k and that's without the unknown such as batteries and quite old (but good condition) inverter, charger etc.

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Are there any filters on the hydraulic oil header tank? There should be a low pressure return line filter. Renew that. The hydraulic manifold block may have a pressure filter in it. Check that. Are there any test points on the manifold, minimess connections? Check standby and running pressures if so. Is the pump a load sensing type, having  a smaller load sensing line going to it from the manifold block, so 3  hoses go to the pump? 

Can't really see what a top end overhaul is going to do for crankcase pressure unless the valve guides are badly worn.. 

I'd be looking at honing the liners & New rings if you're getting blow by.

Have a look at the crankcase ventilation arrangement. Is the filter ok? 

 

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2 hours ago, Tony Brooks said:

I can't really think the following is likely because of the pressures but I am wondering about the hoses  to the bow thruster. On wet exhaust hoses if the inner skin burns through it can form a sort of vale affair that gets pushed across the bore under high speeds, this can stop the raw water pump pumping so it might be the same on a hydraulic hose except it would load the engine and open the PRV.

 

It very definitely does do this in hydraulic hoses, and with exactly the effect you describe.  At high operating the pressures the next thing that happens is all your hydraulic oil decides to come out, usually in the worst spot.

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57 minutes ago, crossley said:

Are there any filters on the hydraulic oil header tank? There should be a low pressure return line filter. Renew that. The hydraulic manifold block may have a pressure filter in it. Check that. Are there any test points on the manifold, minimess connections? Check standby and running pressures if so. Is the pump a load sensing type, having  a smaller load sensing line going to it from the manifold block, so 3  hoses go to the pump? 

Can't really see what a top end overhaul is going to do for crankcase pressure unless the valve guides are badly worn.. 

I'd be looking at honing the liners & New rings if you're getting blow by.

Have a look at the crankcase ventilation arrangement. Is the filter ok? 

 

Thanks for the detail but ?? It's not my boat ... yet and there's no way I can do perform these tests! ARS want £500 + vat to come out and test. With regards to the lump, according to the very thorough engine survey performed by Charles Mills, it does require that amount of work. I do not feel it would be PC to post the contents of, especially as I am only at deposit stage. It hasn't been well maintained, certainly not for the last few hundred hours. Very slack timing chain, quite noisy tappets, water leaks requiring more than new gaskets/sealants, so much oil someones chucked a mass of cat litter beneath the sump etc etc. However, if this goes ahead, I most certainly will seek other opinions from other engineers who can do the work to the same standard.

57 minutes ago, TheBiscuits said:

 

It very definitely does do this in hydraulic hoses, and with exactly the effect you describe.  At high operating the pressures the next thing that happens is all your hydraulic oil decides to come out, usually in the worst spot.

correct me if I'm missing something here but if this were the case, surely the PRV would allow the flow to return to the tank and therefore not putting back-pressure to the engine? It kind of made sense as I typed but I'm not so sure now ... matron!

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13 minutes ago, Markinaboat said:

correct me if I'm missing something here but if this were the case, surely the PRV would allow the flow to return to the tank and therefore not putting back-pressure to the engine? It kind of made sense as I typed but I'm not so sure now ... matron!

 

Depends where in the system the unexpected flap valve has turned up in relation to pump, PRV and thruster,

 

 

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6 minutes ago, TheBiscuits said:

 

Depends where in the system the unexpected flap valve has turned up in relation to pump, PRV and thruster,

 

 

yeah, I thought after posting that if it was en route to the prv, unless the theory that pressure is equal in all directions blows that one out

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10 hours ago, Markinaboat said:

Thanks for the detail but ?? It's not my boat ... yet and there's no way I can do perform these tests! ARS want £500 + vat to come out and test. With regards to the lump, according to the very thorough engine survey performed by Charles Mills, it does require that amount of work. I do not feel it would be PC to post the contents of, especially as I am only at deposit stage. It hasn't been well maintained, certainly not for the last few hundred hours. Very slack timing chain, quite noisy tappets, water leaks requiring more than new gaskets/sealants, so much oil someones chucked a mass of cat litter beneath the sump etc etc. However, if this goes ahead, I most certainly will seek other opinions from other engineers who can do the work to the same standard.

correct me if I'm missing something here but if this were the case, surely the PRV would allow the flow to return to the tank and therefore not putting back-pressure to the engine? It kind of made sense as I typed but I'm not so sure now ... matron!

The PRV on a hydraulic system is in parallel with the motor(s) between the main pump outlet and an open return to the reservoir. Under normal conditions the PRV should not open because if it did it would rob power from the system by allowing the fluid to return to the reservoir.

 

When the direction valve(s)  is in neutral drillings within the valve simply return all the pump output to the reservoir so there is no pressure build up to open the valve.

 

The valve might open momentarily as drive is engaged because to inertia stopping the motor accelerating fast enough to pass all the fluid of as the ports in the valve moved to their new alignment. It will open if the flow gets blocked or a motor fails to turn. You will not notice the momentarily loading of the engine in this case - if it happens at all.

 

If the PRV jammed open you would simply lose power to some degree, if fully open you would get no drive but in all cases the engine will not be loaded and slowed down.

 

Now, in view of the Biscuits confirming my hypothesis I think by far the most likely cause is a faulty hose between pump pump and bow thruster but I cant tell which one as the oil flows in either direction depending upon which way the thruster is set to run. To the best of my knowledge the only diagnostic tool is a pressure gauge that can be inserted into various parts of the circuit but I would expect it to go up to well over 3000 psi (the PRV opening pressure, whatever that is). In your case I would check on either side of the thruster, at the motor under fault conditions. Normally the return side should read all but zero and the other a moderate pressure well below the PRV opening pressure. If you got the PRV pressure on both sides then the return side would be blocked, if on one side the motor would be stationary for some reason , and if you got a low pressure on both sides then the feed side would be blocked.

 

 

You may be able to get an idea of where you have pressure and  where not by feeling how stiff the hoses are.  £500 to me sounds liek a "we don't want the job" price or as the job may be messy and time consuming an "up to" estimate.

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12 hours ago, Tony Brooks said:

The PRV on a hydraulic system is in parallel with the motor(s) between the main pump outlet and an open return to the reservoir. Under normal conditions the PRV should not open because if it did it would rob power from the system by allowing the fluid to return to the reservoir.

 

When the direction valve(s)  is in neutral drillings within the valve simply return all the pump output to the reservoir so there is no pressure build up to open the valve.

 

The valve might open momentarily as drive is engaged because to inertia stopping the motor accelerating fast enough to pass all the fluid of as the ports in the valve moved to their new alignment. It will open if the flow gets blocked or a motor fails to turn. You will not notice the momentarily loading of the engine in this case - if it happens at all.

 

If the PRV jammed open you would simply lose power to some degree, if fully open you would get no drive but in all cases the engine will not be loaded and slowed down.

 

Now, in view of the Biscuits confirming my hypothesis I think by far the most likely cause is a faulty hose between pump pump and bow thruster but I cant tell which one as the oil flows in either direction depending upon which way the thruster is set to run. To the best of my knowledge the only diagnostic tool is a pressure gauge that can be inserted into various parts of the circuit but I would expect it to go up to well over 3000 psi (the PRV opening pressure, whatever that is). In your case I would check on either side of the thruster, at the motor under fault conditions. Normally the return side should read all but zero and the other a moderate pressure well below the PRV opening pressure. If you got the PRV pressure on both sides then the return side would be blocked, if on one side the motor would be stationary for some reason , and if you got a low pressure on both sides then the feed side would be blocked.

 

 

You may be able to get an idea of where you have pressure and  where not by feeling how stiff the hoses are.  £500 to me sounds liek a "we don't want the job" price or as the job may be messy and time consuming an "up to" estimate.

Thanks for the detailed info Tony. If it was my boat, I'd borrow the equipment to do some initial tests. But it isn't. It's also a 2.5 hr drive away so first need to find a weather window  as well as fit it around a very busy work schedule. I hear cake and eat it! 🙂 

 

 

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