I am having problems with an irritating vibration. Both engines accelerate to 1500 with no problem. Port then is reluctant to go on but finally picks up revs with general vibration in the boat. Reluctant to go above 2000 and will occasionally shudder and slow down temprarily.
Both engines free rev to 2750. No signs of vibration or movement in the shafts when boat is moving. No heating of shafts underway. No excessive smoke. Engines regularly serviced Mermaid 225's with about 400 hours. No sign of movement of p brackets inside the boat.
Props are old.
Would love to get back to 34 knots!
Prize of bottle of champagne to anyone who can correctly diagnose problem
John S
Champagne prize
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JohnSK
- Sub-Lieutenant
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- Location: United Kingdom
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Ben
- Admiral
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"occasionally shudder and slow down temprarily" - sounds like fuel starvation to me. Are your return lines clear plastic? If so watch to see for air bubbles moving along. Even with a fuel shortage they will hit high revs with no load as it requires so little fuel to do it.
When were all your filters last changed? tanks cleaned out? Do you use any additive? Maybe you have a blockage and/or sucking air in?
Does not explain vibration though.
Hope this helps.
When were all your filters last changed? tanks cleaned out? Do you use any additive? Maybe you have a blockage and/or sucking air in?
Does not explain vibration though.
Hope this helps.
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tonyhh
- First Sea Lord
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John,
For what it's worth my brother in law in the USA had exactly the same symptoms as you while he was touring Rhode island. Vibration became unbearable for any length of time
Boat came out, shafts removed and props checked; no problems there. Gearboxes removed and checked and found to be fine. Engines mounts suspected and replaced but problem still remained. Fuel lines were checked and filters replaced. Problem still existed.Finally the pumps were sent off. One was fine and the other had a tiny split in a seal. This was replaced, both pumps rechecked and when re-installed he became a very happy chappy!
With that engine off load it revved to 2500 with nil vibration, as soon as load applied on came the vibes and max 1750rpm.
Too much of a coincidence by the sound of it!
Worth contacting Lucas Service, Oakley Road in Southampton on 02380 701133 - postcode is so16 4ll for multimap..ask for Sid and tell him Pete Fisher gave you his number but make sure you change your filters before taking the pumps off
Good luck
Tony
For what it's worth my brother in law in the USA had exactly the same symptoms as you while he was touring Rhode island. Vibration became unbearable for any length of time
Boat came out, shafts removed and props checked; no problems there. Gearboxes removed and checked and found to be fine. Engines mounts suspected and replaced but problem still remained. Fuel lines were checked and filters replaced. Problem still existed.Finally the pumps were sent off. One was fine and the other had a tiny split in a seal. This was replaced, both pumps rechecked and when re-installed he became a very happy chappy!
With that engine off load it revved to 2500 with nil vibration, as soon as load applied on came the vibes and max 1750rpm.
Too much of a coincidence by the sound of it!
Worth contacting Lucas Service, Oakley Road in Southampton on 02380 701133 - postcode is so16 4ll for multimap..ask for Sid and tell him Pete Fisher gave you his number but make sure you change your filters before taking the pumps off
Good luck
Tony
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Scott Pett
- Vice Admiral
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The lack of smoke would suggest lack of fuel rather than faulty or leaking injectors.
Partial fuel blockage to just one or two cylinders would produce misfire like symtoms. This could be the cause of the vibration and also the lack of power.
Once again the engine would still free-rev to 2750 as there might be just enough fuel reaching the injectors to generate enough power.
You could try removing the fuel pipe gallery to the injectors and blowing them through with a compressed air line.
Alternatively it could be that the injection pump is metering in-correctly.
Of course, it might be something silly like water in the fuel, but then you checked the water separators....
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Paul Foulston
- Lieutenant
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I would go with Ben and Scott.
Fuel pumps rarely throw up intermittant faults. High idle of 2750 also suggests pumps are fundimantally OK. I am not an advocate of ripping fuel pumps off. We used to audit pump shops by sending them used but overchecked pumps. 'No fault found' does not seem to exist in their vocabulary.
I would go with pulling air somewhere in the system, this will make engine misfire and shudder and failing to make WOT rpm. Next check for water in your fuel, do not assume ANYTHING, is OK change all the filters. Finally check for a restriction in your return line, this can cause engine failing to meet rated RPM under load.
Hands up those of us who press up their tanks before putting their boat to bed. Not many judging by the early morning traffic jam on the fuel pontoon.
Big bollocking here, hot fuel, half empty tanks, cold nights, 'hey presto'loads of water. Add to that modern fuel refining methods which pass superheated steam though the oil as part of the refining process. Even red diesel is prone to want to 'grab' water as a result. Topping off tanks is cheaper than fighting the bug and or sorting out 'water in fuel' related problems.
Here endeth the lesson
Paul
Fuel pumps rarely throw up intermittant faults. High idle of 2750 also suggests pumps are fundimantally OK. I am not an advocate of ripping fuel pumps off. We used to audit pump shops by sending them used but overchecked pumps. 'No fault found' does not seem to exist in their vocabulary.
I would go with pulling air somewhere in the system, this will make engine misfire and shudder and failing to make WOT rpm. Next check for water in your fuel, do not assume ANYTHING, is OK change all the filters. Finally check for a restriction in your return line, this can cause engine failing to meet rated RPM under load.
Hands up those of us who press up their tanks before putting their boat to bed. Not many judging by the early morning traffic jam on the fuel pontoon.
Big bollocking here, hot fuel, half empty tanks, cold nights, 'hey presto'loads of water. Add to that modern fuel refining methods which pass superheated steam though the oil as part of the refining process. Even red diesel is prone to want to 'grab' water as a result. Topping off tanks is cheaper than fighting the bug and or sorting out 'water in fuel' related problems.
Here endeth the lesson
Paul
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Ben
- Admiral
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John,
Another thought, its the end of the year, how dirty is your bottom? Where do you keep the boat? There has been a really big barnacle problem in Porto Solente this year, its prevented a couple of people I know form getting on the plane. Maybe this is contributing. Although I suspect a fuel problem.
Paul, quite right, I always leave PT2 full, change all filters every year and use Soltron, quite expensive but seems to do the trick. I know others use Fuelset. Also with full tanks she's low at the stern so bilge water runs aft and I can sponge her dry, it was the same with cascade.
Happy new year all.
Another thought, its the end of the year, how dirty is your bottom? Where do you keep the boat? There has been a really big barnacle problem in Porto Solente this year, its prevented a couple of people I know form getting on the plane. Maybe this is contributing. Although I suspect a fuel problem.
Paul, quite right, I always leave PT2 full, change all filters every year and use Soltron, quite expensive but seems to do the trick. I know others use Fuelset. Also with full tanks she's low at the stern so bilge water runs aft and I can sponge her dry, it was the same with cascade.
Happy new year all.