andy4502 Posted October 7, 2017 Report Share Posted October 7, 2017 Hi, I have a 1993 narrow boat powered by a Thorneycroft 27HP, have recently been losing power/dropping out of drive and there is a significant and increasing delay when pushing the throttle forward/back before the drive kicks in (with an audible and felt thump!). Can anyone suggest things I can do before I ask for professional advice on this? (Its already cost me a fortune!!). Any thoughts gratefully received, including expected life of engine/clutch/gearbox and likely/best replacement and cost. Thanks - have had a fantastic summer boating by the way (Boat is a home fit out 1993 V hulled 44ft/6'10" on the mon and brec canal and I purchased this year and have had everything on survey completed (hull/electrics/new exhaust/engine bay clean and serviced engine). There is no rev counter so cant say exactly, however a low tickover in forward drive achieves about 1 mph and middle power about 2/3 mph - haven't gone faster than that as the canal is very shallow.) Link to comment Share on other sites More sharing options...
cuthound Posted October 7, 2017 Report Share Posted October 7, 2017 Sounds like a gearbox problem. What gearbox is it? Have you checked the gearbox oil level? On some gearboxes (PRM 120 & 150, may be others as well) a low oil level will cause intermittent loss of drive. 1 Link to comment Share on other sites More sharing options...
andy4502 Posted October 7, 2017 Author Report Share Posted October 7, 2017 no - will try that first - have no idea what the gearbox is - not even sure I know where it is!!! (after many years of knowing nothing about engines am now trying to learn). This should have been sorted in the full service surely? Link to comment Share on other sites More sharing options...
WotEver Posted October 7, 2017 Report Share Posted October 7, 2017 1 minute ago, andy4502 said: have no idea what the gearbox is - not even sure I know where it is!! You’ll find it between the engine and the prop 1 Link to comment Share on other sites More sharing options...
rusty69 Posted October 7, 2017 Report Share Posted October 7, 2017 4 minutes ago, WotEver said: You’ll find it between the engine and the prop Preferably inside the boat. 1 Link to comment Share on other sites More sharing options...
MtB Posted October 7, 2017 Report Share Posted October 7, 2017 3 minutes ago, andy4502 said: no - will try that first - have no idea what the gearbox is - not even sure I know where it is!!! (after many years of knowing nothing about engines am now trying to learn). This should have been sorted in the full service surely? Yes it should, but relying on trades people to do their job properly can be very disappointing. What exactly did you ask for when you booked this 'full service'? An engine service possibly? If so I can't imagine the bloke servicing the gearbox for free and unrequested... 1 Link to comment Share on other sites More sharing options...
ditchcrawler Posted October 7, 2017 Report Share Posted October 7, 2017 12 minutes ago, cuthound said: Sounds like a gearbox problem. What gearbox is it? Have you checked the gearbox oil level? On some gearboxes (PRM 120 & 150, may be others as well) a low oil level will cause intermittent loss of drive. On the bottom of the blue line 1 1 Link to comment Share on other sites More sharing options...
andy4502 Posted October 7, 2017 Author Report Share Posted October 7, 2017 (edited) yes - I have also learned to become slightly cynical about marina services and what you get for the considerable amount of money spent!! ok - check oil on gearbox - anything else anyone? PS boat is beautiful - to be fair to the marina who did this (ABC @ Gotyre Wharf) also painted her (wife on bow did not come included in purchase) : Edited October 7, 2017 by andy4502 Link to comment Share on other sites More sharing options...
StephenA Posted October 7, 2017 Report Share Posted October 7, 2017 Does it do the same in reverse as forward? Do you know when the gearbox oil was changed? It should be changed quite regularily and should be using ATF rather than engine oil. It would sound like the gear arm mechanism needs adjusting... but it could be that the clutch plates are just about worn out which means a rebuild or a swap for a rebuilt box. 1 Link to comment Share on other sites More sharing options...
Bee Posted October 7, 2017 Report Share Posted October 7, 2017 A service should mean at the very least new oil and filter and a quick look around, I would hope that all levels and antifreeze should be checked as well and belts and couplings looked over. the chances are though that wear in the gearbox will not be discovered unless there is something obvious. The first thing to do though is have a look at the gearbox. On the side of it is a lever. I think its on the right hand side looking from the rear in the picture. When you go forwards and backwards this is the lever that changes the gears in the box. The cable might not be moving the lever properly, try moving it by hand, see if it is moving fully. If not then that is the problem and the cable needs adjusting. Check the oil in any case. If the oil is correct and the lever is moving fully then you probably need to get professional help. Others may know more. 1 Link to comment Share on other sites More sharing options...
andy4502 Posted October 7, 2017 Author Report Share Posted October 7, 2017 (edited) ok - thanks StephenA and Bee - that is a good place to start and I will let you all know. If it is 'tired' which is what I suspect (boat sat around for a couple of years not moving) then what would a gearbox rebuild cost? Also - what would people recommend in terms of me learning this stuff - do a course, or just try to do it with help from here and you tube? Edited October 7, 2017 by andy4502 Link to comment Share on other sites More sharing options...
StephenA Posted October 7, 2017 Report Share Posted October 7, 2017 Our PX'd rebuild was £550 plus £85 for a new drive plate (which was about 27 years old) Link to comment Share on other sites More sharing options...
andy4502 Posted October 7, 2017 Author Report Share Posted October 7, 2017 thanks - in answer to your question 'does it do this in reverse as well' - yes in terms of taking time to drop into gear - not in terms of dropping off power - however this is probably as I don't run in high revs in reverse for a long (minutes) time and therefore it probably would. Link to comment Share on other sites More sharing options...
Rose Narrowboats Posted October 7, 2017 Report Share Posted October 7, 2017 (edited) It's a Hurth/ZF mechanical box, so low oil level won't be a factor in engagement. As mentioned cable adjustment is a possibility worth checking, or it might have the wrong oil in it (it should be ATF), but more likely the clutch packs are knackered. If so, my advice is buy a new one. Extensive (and expensive) experience with a couple of Hurth's we had in our fleet has taught me that by the time the clutch packs are knackered, so many other bits are out of tolerance that they are not economic to rebuild properly and if not rebuilt properly will usually not last more than a few hundred hours before the problem recurs. Once a Hurth clutch has picked up drive, they don't tend to lose it again, so I'd suggest the loss of power after a period of time is more likely down to leaves given the time of year. Edit to add: because of the design of the clutch plates, the thump is normal when the drive does take up. Edited October 7, 2017 by Rose Narrowboats 1 Link to comment Share on other sites More sharing options...
andy4502 Posted October 7, 2017 Author Report Share Posted October 7, 2017 rose - thanks, depressing but hey ho that's the way it goes I suppose. Will obviously check oil and other advice first - well done on knowing the type of box!! How much is a replacement? I definitely get loss/drop out of drive - yes there is the leaf issue which was bad last couple of days, but this was a clear drop out of drive not just leaves. Link to comment Share on other sites More sharing options...
Rose Narrowboats Posted October 7, 2017 Report Share Posted October 7, 2017 There are several versions of that box, identical except in terms of scale. Given the size of the engine its probably either a 100 or 125 (later ZF10 and ZF12). Don't think the ZF10 is available any more, the ZF12 is at about £1000. The smaller (mechanical) PRM boxes are designed to be a straight swap and are a bit cheaper. Link to comment Share on other sites More sharing options...
andy4502 Posted October 7, 2017 Author Report Share Posted October 7, 2017 (edited) I wonder if it is worth doing a full replacement of engine/gearbox etc as it is likely the engine is in a similar state? would this be a cheaper in the long run approach and how much!! We really like the boat layout etc and have brought her fully back to life and would like to keep her for many years to come - thoughts? Edited October 7, 2017 by andy4502 Link to comment Share on other sites More sharing options...
Rose Narrowboats Posted October 7, 2017 Report Share Posted October 7, 2017 Ultimately it's your boat so your choice, but from the condition of the engine bay it doesn't look as if the engine is leaking oil, so if it's it not burning it either then there's probably not much (if anything) wrong with it and the gearbox should be no more than a morning's worth of work to change. Someone who is familiar with it could probably do it in a couple of hours if under pressure. Engines will usually outlast quite a few small mechanical gearboxes on canal use where they do a lot more gear engagement/dis-engagement than at sea. If the gearbox outlives the engine it can always be fitted to the new engine. 1 Link to comment Share on other sites More sharing options...
Up-Side-Down Posted October 8, 2017 Report Share Posted October 8, 2017 11 hours ago, StephenA said: Does it do the same in reverse as forward? Do you know when the gearbox oil was changed? It should be changed quite regularily and should be using ATF rather than engine oil. It would sound like the gear arm mechanism needs adjusting... but it could be that the clutch plates are just about worn out which means a rebuild or a swap for a rebuilt box. SOME gearboxes use ATF and some use engine oil and some started out using ATF and the specification changed from ATF to engine oil (the PRM 120 being a case in point – and yes, I did check direct with PRM in case a typo had slipped in at some point). Always check the specification. 1 Link to comment Share on other sites More sharing options...
cuthound Posted October 8, 2017 Report Share Posted October 8, 2017 11 hours ago, andy4502 said: Also - what would people recommend in terms of me learning this stuff - do a course, or just try to do it with help from here and you tube? River Canal Rescue do courses. https://shop.rivercanalrescue.co.uk/Courses/CourseLanding.aspx Either a traditional "classroom" course or a one to one "show you how to service your own boat" course. I recommend the latter, as it gives you familiarity with your own boat. It lasts 4 hours and if the service is finished in less than the 4 hours, the technician will show you how to fix/test other things on your boat until the 4 hours are up. 1 Link to comment Share on other sites More sharing options...
StephenA Posted October 8, 2017 Report Share Posted October 8, 2017 1 hour ago, Up-Side-Down said: (the PRM 120 being a case in point – and yes, I did check direct with PRM in case a typo had slipped in at some point) Oddly enough the PRM website http://www.prm-newage.com/help-centre-marine States: Q: What Oil does my gearbox take? A: A mechanical gearbox (PRM 60, 80, 90, 120 or 125) must use automatic transmission fluid (ATF) Dextron II or III All hydraulic gearboxes must use mineral 15W40 (not synthetic) Link to comment Share on other sites More sharing options...
andy4502 Posted October 8, 2017 Author Report Share Posted October 8, 2017 So, just to summarise the position so far for my little brain: Check lever on side of gearbox for travel and adjust check oil and ensure is correctly filled with the right oil (some debate but need to know exact gearbox) if none of this works I am doomed to 'Bring out another thousand' (BOAT) and get a replacement gearbox and I will do the course Thank you all very much - any further thoughts please add Link to comment Share on other sites More sharing options...
StephenA Posted October 8, 2017 Report Share Posted October 8, 2017 Yes - check that when you move the throttle/gear lever into forward that the arm on the side of the box moves properly - you might want to check that it has moved properly by hand but of course don't do that with the engine running. Then once you've see how its travelling adjust the cable appropriately to either push or pull the lever further If its a Hurth then it should have ATF in it (which is usually pink) - its important not to mix ATF and Engine Oil. If you have to replace the box then its worth looking at the condition of the spring/drive plate which connects the engine to the gear box and replacing it at the same time Link to comment Share on other sites More sharing options...
OldGoat Posted October 8, 2017 Report Share Posted October 8, 2017 (edited) Totally off topic but - the engine bay is one of the cleanest that I've seen on here and the hull looks almost new with shiny paint. The Management adds to the feeling of a happy boat... In contrast the engine looks tired and neglected, so much so that I wonder whether its a spare that someone had knocking around and it's just been popped in? The exhaust lagging and coolant pipes look new so it's surprising that the engine should looks so bad. If so, perhaps it's possible a matter of adjustment of the controls. I'd check the gearbox oil for level and the correct type. Check the engine oil for level and colour - If it's very black and the engine smokes when running then your suggestion of an engine transplant may be sensible. There was a link on here recently of a yard who had a couple of new small Beta engines at a reasonable price. If you're interested perhaps someone could point you to the thread and give you an independent opinion. Edit: linky - http://www.marineenterprisesltd.co.uk/ Select used narrowboat engines or find the Beta engines in the general listing, but they would need converting from 'heat exchanger cooled' Edited October 8, 2017 by OldGoat link to used engines Link to comment Share on other sites More sharing options...
ditchcrawler Posted October 8, 2017 Report Share Posted October 8, 2017 13 hours ago, andy4502 said: rose - thanks, depressing but hey ho that's the way it goes I suppose. Will obviously check oil and other advice first - well done on knowing the type of box!! How much is a replacement? I definitely get loss/drop out of drive - yes there is the leaf issue which was bad last couple of days, but this was a clear drop out of drive not just leaves. When you say "Drop out" do you mean it goes into neutral, or stays in gear but with no output? Link to comment Share on other sites More sharing options...
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