We have a Hunter 50 just 3 years old and are sailing in Malaysia. Coming up the coast to Rebak Island we found that the engine would not rev over 1800 rpm under load and in neutrl it only revved to 2000rpm. We motored sailed most of the way but missed the extra speed we should have been able to do. At Rebak Island we have a very good Australian mechanic looking at the problem but even he is perplexed. Having surfed through lots of threads it does appear to be a problem many others have had with varying solutions. As it happens in neutral we eliminate the prop. The boat has been at Puteri Harbour in the marina idle for 6 months and we have only just returned from Australia. Our trip up the coast started alright but after the first 24 hours we noticed the problem when trying to avoid a ship. We pulled into shore and replaced the primary filter with no change. We decided to continue on. At Rebak we have tried fuel direct from a can, put a pump in the fuel line and checked and bled both filters. There is now bluish smoke once 2000rpm is reached. Throttle cable has been checked. No change in the revs. Next avenue will be check the injectors. Does anyone have any ideas?
Loss of power Yanmar 4jh4-hte
- Thread starter smartchoice
- Start date
i'd have the mechanic check the play on the throttle linkage. if it's a morse cable, they can stretch and loosen over time and they will give you the low-idle / no top end issue you are having. pulling the cable tighter is a simple matter of loosening the screw that holds the cable onto the throttle lever on the engine. (while your are at it have the mechanic grease and adjust both the gearshift and throttle morse cables.) if the throttle linkage is not your problem, spend $50 and get an online subscription to boat diesel.com they have a Yanmar board. as a member you can post questions.
I had to change the part of the exhaust hose because it was collapsing and restricting the flow. You could see it hapenning as you gave the engine more throttle. No more problems afterwards.
Sorry ... finger fumble. Engine has 1400 hrs. Pretty disappointed! Watching the exhaust ... When revs go past 2000 immediately get lots of bluish smoke and water mix exhausted looks unusual. Like frothy but disapates quickly. Mechanic is going to check or remove injectors today.
By the way a priority when buying the next boat will be engine installation. There is no room to get to anything. Mechanic has said engine will have to be lifted out to be able to remove injector pump. Why do we buy new boats?
I have tried to register on boat diesel but nothing happens. Might be my java script is too old but thought it should at least do something.
You mean like this one .......................
I chopped this one up at about 4-500 hours. I show no smoke under heavy load but still seem to suffer from excessive coking since the engine and boat were brand new. All the usual engine operation and maintenance tactics as well.
I think checking the exhaust elbow is a easy place to start. If that checks out...
If the injectors were bad I don't think you would see blue smoke. Blue smoke indicates that engine oil is being burnt. Boat has sat idle for 6 months. Did engine work properly 6 months ago? If so then problem has occurred during non use. Oil can get to combustion chamber by going past valve guides or seals, piston rings or turbocharger bearing seals. Compression check would indicate if valve seals or piston rings are bad, perhaps a cylinder differential leak-down test would also be needed. Perhaps there is internal rust from sitting idle?
I think that the turbocharger is the problem as it could certainly cause the blue smoke from oil getting past the bearing seals and also explain why the engine will not rev faster than 2000 rpm under no load. If the turbocharger is not operating properly boosting the airflow, that would cause the loss of power. Perhaps a pressure gauge could be used to see if the turbocharger is working properly.
Hope this helps, good luck!
If the injectors were bad I don't think you would see blue smoke. Blue smoke indicates that engine oil is being burnt. Boat has sat idle for 6 months. Did engine work properly 6 months ago? If so then problem has occurred during non use. Oil can get to combustion chamber by going past valve guides or seals, piston rings or turbocharger bearing seals. Compression check would indicate if valve seals or piston rings are bad, perhaps a cylinder differential leak-down test would also be needed. Perhaps there is internal rust from sitting idle?
I think that the turbocharger is the problem as it could certainly cause the blue smoke from oil getting past the bearing seals and also explain why the engine will not rev faster than 2000 rpm under no load. If the turbocharger is not operating properly boosting the airflow, that would cause the loss of power. Perhaps a pressure gauge could be used to see if the turbocharger is working properly.
Hope this helps, good luck!
Injectors checked ok. They feel it is the fuel pump. Really appreciate your inputs. Heading back to put them back in and check exhaust bits. Pump very difficult to get to. We just have to keep eliminating things
Well I don't believe it ... it is all working. Replaced the injectors, also freight from Australia had turned up so the secondary filter was replaced. Diesel from that did look pretty dirty. Before starting engine the mechanic removed a tube where the boost pressure comes from ... maybe turbo???... and when engine was running he blew into it and it revved fine with no smoke. He was unsure if that had fixed the problem as he could here the turbo working. Re-attached everything and it worked fine. Quite bizarre but perhaps if he had tested before the blow job it might have worked. Never change three things before testing. Either way, next options would have been difficult! Having done soooo much research on this I now understand diesel engines! Thank you all for your input ... I have found the site amazing.
You're quite right. A good friend told me years ago: "Only do ONE thing at a time or you'll never know what the problem really was."
Still we probably will not know but he took the old filter and is going to cut it open. We believe it was the filter but he thinks a blockage in the turbo tube thing. Great load off our plate as we bought new to avoid problems like this. I suppose your car does not start every time but this was a difficult one.