Mike Fox Posted October 1, 2011 Report Share Posted October 1, 2011 (edited) Can anyone explain the following sequence of events that happened this morning shortly after leaving on the 9.30 bridge lift? Motoring down the main channel, when I suddenly heard the engine revs die, and experienced a loss of power, but the engine kept running. The engine is a 21 year old Volvo Penta 2003, 3-cylinder, 28 h.p. diesel. Suspecting weed/rope round the prop, I engaged forward and reverse several times to see if the cutters could clear it. No difference. I next tried revving the engine in neutral, and while revs did increase, they were very slow to pick up. The water pump appeared to be working still, but the engine was producing clouds of smoke at this point. Tried stopping and starting the engine a few times to see if that might help...but no difference was seen. (At this point had boats everywhere, a wicked flood tide, and no chance of turning to starboard due to the Middle Mud, so sailed towards Parkstone where Carol and I picked up a mooring buoy on that side of the channel). Next checked the throttle linkage (having had cables fail before). Again, this was not the cause. Checked the weed strainer, and this was clear, and the pump was cold when restested, so not a blockage/siezure. Checked the engine oil, still which was still on the middle of the dipstick and fairly clean with no signs of water emulsification, having done oil and filter change about 20 engine hours ago. Restarted the engine with the engine bay open, and the problem persisted, but was now able to hear a "whump whump" noise, as if at least one of the three cylinders was not firing. Was now suspecting something dire, so phoned up a marine engineer, who suggested head gasket which would warrant a tow home, or a fueling issue. I asked him what he'd check next, and he suggested opening bleed points to see if fuel was being stopped at some point. I next opened the bleed point on the secondary fuel filter. This was under extreme pressure, and I was sprayed with diesel. I've never see such high pressure here before when bleeding the system. After the pressure subsided, I checked to see if the lift pump would "pulse" fuel through, and it did, so closed the bleed point again while pumping by hand. Again, tried to start the engine, and this time it fired perfectly on all 3 cycinders, and has continued to run since (but took boat back to its berth), including up to cruising speed. Question: What caused the engine power loss, and how did relieving the pressure on the bleed point appear to correct it? Any advice welcome, as I cannot really explain what went wrong, or what's to stop it happening again! Oh, and have already asked the marine engineer to check it over next week, and the boat will remain lashed to the pontoon until then! Thanks, Mike PS Had the great offer of assistance from Dave (Pirky) on Alice II if needed, which was much appreciated as a possible lifeline home! Edited October 1, 2011 by Mike Fox Quote Link to comment Share on other sites More sharing options...
duncan Posted October 1, 2011 Report Share Posted October 1, 2011 honest answer is no clue........but if grasping at straws it seems 1. fuel related 2. probably one cylinder only logical conclusion I have is that there was a temporary blockage to one injector, something held in place by the pressure build up (fuel pump would continue to deliver even if the injector was totally blocked) that got released when the pressure seal was broken. whatever it was may still be in the area, or gone... again guessing - it's gone. personally I would remove injectors and disconnect. prime through an amount of fuel, wash injectors, replace, prime etc, also check the secondary fuel filter for signs of biological material. Quote Link to comment Share on other sites More sharing options...
Coddy Posted October 1, 2011 Report Share Posted October 1, 2011 honest answer is no clue........but if grasping at straws it seems 1. fuel related 2. probably one cylinder only logical conclusion I have is that there was a temporary blockage to one injector, something held in place by the pressure build up (fuel pump would continue to deliver even if the injector was totally blocked) that got released when the pressure seal was broken. whatever it was may still be in the area, or gone... again guessing - it's gone. personally I would remove injectors and disconnect. prime through an amount of fuel, wash injectors, replace, prime etc, also check the secondary fuel filter for signs of biological material. Mike I would agree with duncan that a partial blockage in the injector side of delivery. Have the injectors been cleaned/checked for spray patten? I know that you use the engine quite often but depends on hours used for injector checks. Might be worth adding injector cleaner to the fuel, some poh poh the stuff but I found it to work both in a 4x4 and my old Romany. Also may be woth adding a small amount of 2-stroke oil to the fuel, this not only lubricates wherever the fuel goes but also quietens down injector pumps and can slightly improve performance. Add 2oz of 2 stroke oil to each 20 gal of diesel. This is quite a common practice and does no harm to pump or injectors. May be worth replacing the fuel filters as well and going for a finer filter if poss. Perhaps when you had tank issues bits may well be getting through the system. Dave Quote Link to comment Share on other sites More sharing options...
Mike Fox Posted October 3, 2011 Author Report Share Posted October 3, 2011 Thanks chaps.... Injectors were removed and serviced in July, when I had a compression test done. I have changed to non-Volvo filters, as was unable to find the usual ones last time, so perhaps that's a check/change I could make. Hadn't thought of that! Additives, yes, sounds a good idea - injector cleaner, head de-coker, diesel bug killer, extra lube etc.....but where do you stop ? Have also had the suggestion of a couple of tank fulls of road diesel, as the additives for cars also apply for marine use. My last tank of diesel was from Cobb's about 10 hours ago...usually use Coralls. Wonder if their fuel has higher bio-diesel content, which can sometimes cause problems? Keep them coming! Thanks, Mike Quote Link to comment Share on other sites More sharing options...
niggle Posted October 3, 2011 Report Share Posted October 3, 2011 Not familiar with you're system i.e layout of components But at a guess on you're description injector or pipe as you had a massive build up of pressure which would/could happen if injector is not operating,that said if injector leak-off is fitted it should of been released on that circuit unless pipe or injector had totally jammed/blocked? Make sure filters/seals haven't started to break up? Internal pipe linings are ok and not starting to break up or flake? Good luck Mike let us know if you find the problem Quote Link to comment Share on other sites More sharing options...
fisherman1055 Posted October 3, 2011 Report Share Posted October 3, 2011 Mike I have occasionally found the engine to run unevenly , lumpy( possibly on several cylinders) only to sort its self out when restating I have put this down to air in the pipes had a similar issue with Citreon Xantia, and on bleeding pipes was greeted with a diesel shower. but this stopped problem have not had repeat of problem on boat for 6 months good luck Mike tony Quote Link to comment Share on other sites More sharing options...
Mike Fox Posted October 4, 2011 Author Report Share Posted October 4, 2011 Update: The marine engineer has removed injectors and cleaned up, finding one of the needles marked as if it had been "scuffed" by some grit or something. His suggestion is something got past the primary and secondary filters, wedged a needle open, and the non-combusting cylinder pressurised the copper piping back up the system. between the filters and the injectors. The pressure and grit stopped the needle dropping again. My relieving the pressure caused the injector needle to lift fully, flushing the grit out, and restoring the injector to operational condition. Not sure I understand why the fuel feed back to the tank didn't clear the excess pressure, but it sounds credible. He's re-assembling. Mike Quote Link to comment Share on other sites More sharing options...
Coddy Posted October 4, 2011 Report Share Posted October 4, 2011 Good to hear it is not a major repair job. Dave Quote Link to comment Share on other sites More sharing options...
Stuie Posted October 4, 2011 Report Share Posted October 4, 2011 Pleased to hear that it's good news Mike - for a change. Quote Link to comment Share on other sites More sharing options...
Mike Fox Posted October 6, 2011 Author Report Share Posted October 6, 2011 Injector now sorted, all three re-checked and re-installed. Engine fired up and back to operational! The return feed to the tank has only a small outlet diameter, and hence stopped the unusual pressure from bleeding off. Thanks for all of the comments folks. Let's just hope that was the cause! Mike Quote Link to comment Share on other sites More sharing options...
duncan Posted October 6, 2011 Report Share Posted October 6, 2011 Update: The marine engineer has removed injectors and cleaned up, finding one of the needles marked as if it had been "scuffed" by some grit or something. His suggestion is something got past the primary and secondary filters, wedged a needle open, and the non-combusting cylinder pressurised the copper piping back up the system. between the filters and the injectors. The pressure and grit stopped the needle dropping again. My relieving the pressure caused the injector needle to lift fully, flushing the grit out, and restoring the injector to operational condition. Not sure I understand why the fuel feed back to the tank didn't clear the excess pressure, but it sounds credible. He's re-assembling. Mike and he had the benefit of pulling it all apart.... anyhow, glad that is resolved Quote Link to comment Share on other sites More sharing options...
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