[Amel Yacht Owners] Re: ONAN FAULT BRAKER
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Olivier Beaute
Good afternoon Paul, your generator is a different kind as the later ones (like Bill's). When the fault breaker trips, this is mainly because of 4 possible problems: -too high temperature on cooling fluid -too high temperature at exhaust pipe -not enough oil pressure -no charge from the 12V alternator So before resetting the small red knob, check: -cooling fluid level and fan belt (driving the cooling fluid circulator) -seawater flow (therefore, impeller and heat exchanger tubings) -oil level -alternator belt and wiring Now that you have found the cause (broken impeller) of the fault breaker to trip, as your impeller was rather new, you should inspect the whole seawater circuit, especially at heat exchanger intake, where pieces of rubber impeller may have collected and prevent a good water flow (and then cause the impeller to destroy because it forces). If you can't find any piece of rubber or dirt, you should check the exhaust elbow where seawater mixes with exhaust gas. It may be partly clogged with soot (according to the engine hours and age). Have a good working day! Olivier On Monday, July 13, 2015 12:51 PM, "osterberg.paul.l@... [amelyachtowners]" wrote: Found the problem, broken impeller, but there are no flash indicating what problem
Thank you SY Kerpa |
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Thank you
Can I reuse the gaskets after cleaning the heat exchanger and elbow? Sy Kerpa |
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Bill & Judy Rouse <yahoogroups@...>
Paul, The elbow will need a new gasket (GASKET-EXH OUT CONN Part# 0185-6853) because the old one will be compressed, and sometimes the end caps and gasket can be reused, but don't try it until you have a spare, unless you need to. I always have 2 end caps and gaskes and o rings, sold as a kit with 1 end cap, gasket and o ring in each kit (Heat Exchanger Cap Kit Part# 130-5176). NOTE: Parts numbers above for a Onan Model MDKAV, but I think they are the same on yours...you should check this. Ok, you have an older Onan model than I thought you had. That switch will open with too high heat (water & exhaust) and too low current or too low of oil pressure. You say that your impeller is faulty...but you could also have:
It could be just the impeller, but if that impeller is less than 12 months old, and/or less than 250 hours you will likely have at least one more issue...one more of the issues I described above. The missing impeller blades will be inside the outlet from the water pump and inside the "water pump end" of the heat exchanger. Best to use a wet/dry vacuum. GENERAL PROCEDURE FOR REMOVING LOOSE BLADES ON THE ONAN: Cut off the saltwater flow to the Onan (normally at the sea-chest main valve) and with the wet/dry vacuum running, remove the outlet hose from the water pump. Suck the water and debris out of the water pump outlet, then out of the hose.The wet/dry vacuum will suck all of the residual water that is currently in the lines, water pump and heat exchanger...this could be as much as 4 liters. Now with the wet/vac running remove the heat exchanger end cap (but I would not remove it unless you have a spare...these are fragile and yours may break when removed). If you do not have a wet/vac, do something to take care of all of the saltwater you are going to get. Once you have the end cap completely off, continue with the wet/vac sucking debris from the exchanger...then inspect the wet vac for blades. If you do not have a wet/vac, the job of finding these blades will be much more difficult using picks and pliers, etc. You may find more blades than you are missing because previous impeller failures did not find blades. While you have the heat exchanger empty of water is a good time to replace the zinc on the heat exchanger. You should be sure that the line from the sea chest to the Onan is free and clear...look at these 5 or 6 photos for reference: Bill BeBe On Mon, Jul 13, 2015 at 2:40 PM, osterberg.paul.l@... [amelyachtowners] <amelyachtowners@...> wrote:
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rossirossix4
Does anyone know if alternator output failure trips the newer Onans? The alternator is a very expensive item so we don't carry one. Also, has anyone sourced a reasonable Onan alternator spare?
Bob KAIMI SM429 (2004) |
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Bill & Judy Rouse <yahoogroups@...>
Bob, good question. I am not sure, but I know that if you disconnect the battery, it will shut down, and if the manual states if battery voltage is above 19.2VDV, it will shut down (code 29), so I suspect that there is battery voltage monitoring with shutdowns at the high of 19.2 and a low of X. If I am right, you could disconnect the belt on your Onan and it will run fine until the battery gets too low or the engine overheats. That belt also turns the coolant water pump and without the belt, it will overheat! In the coming months I plan to change that belt and test this for a minute. If anyone is changing a belt before I get to it, please test this for us. On an entirely different matter, Bob, have you purchased a wet/vac? Bill Rouse
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The heat exchanger was full of white crust as well as parts from the impeller
By mechanical removal of the crust and by treating with first white winneger and thereafter oxalic acid I gott rid of the crust No problem to reuse the gaskets Sy Kerpa |
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Bill & Judy Rouse <yahoogroups@...>
Paul, Good, you got it cleaned. But you also probably saw how delicate those end caps are. I am glad you were able to reuse them. I am curious, how many impeller blades did you find in there? And, can you see the value of using a wet vac to suck the blades out of the heat exchanger? Bill Rouse
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It was a handful of blades but plenty of crust i don't know if it was calcium based crust or not
However a wet vacuum would have made the job easier Paul SY KERPA |
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