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Post by Zanshin on Apr 19, 2015 14:23:42 GMT
My Cummins-Onan genset on Zanshin goes through impellers with a vengeance. While I've heard that this is not atypical for this family of generators, I had to replace another impeller the day before yesterday and while I was at it I cleaned out the heat exchanger in order to remove any collected debris and remnants/fragments of old impeller blades. This turned out to be a major task - I had to remove all of the soundproof housing to access that part of the generator. In order to remove the housing I had to remove several hoses whose hose-clamps didn't feel like budging. Once the housing was off I had access to one side of the heat exchanger which also had the Zinc anode, which I removed in order to replace; at least I had planned on removing it but the Zinc part broke off and stayed inside the heat exchanger. So off comes the end and out come my tweezers and after a bit (well, a lot) of work I had the Zinc removed and the new one installed as well as the "hot" end of the heat exchanger re-sealed. In order to get at the other end of the heat exchanger I needed to remove the oil filter, which was in the way. And in order to remove the oil filter I had to drain all the oil and perform an oil change. This was made difficult since I had the old cooling water pump and impeller removed as well as many hoses unplugged, so I couldn't warm up the engine in order to facilitate the oil change. But I managed somehow, and removed quite a bit of debris from the heat exchanger. Then came the task of putting everything back in place and seating the new impeller; in total I worked non-stop for about 7 hours for what should have been a simple job. I believe that the debris plugging up my heat exchanger caused not only an inadequate flow of water to cool the engine but give the system sufficient back pressure to prematurely age the impeller(s) that I kept on feeding my generator! My lesson, that I'd like pass on, is that if you wait too long to replace the impeller on your generator (or main engine) and lose blades, please take the time to clean them from the heat exchanger in order to prolong the life of the next impeller.    |
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Post by abgreenbank on Apr 19, 2015 17:57:22 GMT
As an owner of a low hours, about 5 so far Cumins 6.5kva generator probably the size smaller than yours, just wondering how long your impellors last?
my genset has the option for 50 or 60 hz , but for 60 hz the engine is closer to 3000rpm rather than 2400 rpm for 50 hz, does yours run at 60 hz and 3000 ish rpm or is it a 1500rpm model. Just wondering if operating Rpm has a significant influence on impellor life.
My DS 50 also looks to have much less space to work on the genset than you have, so no looking fwd to its first service.
rgrds
ab
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Post by Damir on Apr 19, 2015 20:39:08 GMT
Hi Zanshin
It is recommended that after the impeller is broken open, the first water cooler because parts of the impeller shut the flow of cooling fluid. When you open the cooler look for shells (especially in warm seas) once you move in them difficult to remove because there are conditions for their growth and ideal for us horror. This applies to engines genetatore compressors (all what is cooled with sea)
Regards Damir |
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Post by sailbleu on Apr 22, 2015 6:30:41 GMT
Same thing for the engine's raw water pump impeller Zanshin .
I replace mine at least every 2 years , and depending on running hours annually if neccessairy . Although it' s not easy to tell with a typical non-functional Volvo Penta hour meter , but a new one is on its way :-)
When removing the old one , Most of the time I see fracture(s) on the base of the impellers blade(s) , that will eventually lead to blade(s) breaking off , clogging the heatexchanger , and in worst case scenario overheating the engine due to no raw water pumping with possible devastating effects.
All for a 25 € impeller and an hours work.
Next month I will be replacing mine again before our season starts .
It's best you install a new one after the winter so the new impeller is not squeezed in the housing for all those cold months.
Unless you sail around the year of course.
Regards
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Post by rxc on Apr 22, 2015 22:13:31 GMT
Six months after I had a genset installed, it sucked up a jellyfish in the Chesapeake Bay and stopped. I cleaned out the mess, restarted, and then spent 7 years trying to figure out why the cooling water flow was too low, causing the genset to stop all too often on high temperature. I changed impellers, took down the hoses, even removed the end caps on the genset heatexchanger to check for impeller parts. Nothing.
Then, finally, in a fit of desperation here in Florida, where the water temperatures are too high to make up for the low flow, I looked at the hose from the thru-hull to the strainer. It was clear. But I continued to see if there was anything in the thru-hull or the seacock, and in the process I removed the 90-degree tailpiece that was threaded into the seacock. Lo-and-behold, there was a bit of mummified jellyfish in the tailpiece, blocking the flow from the thruhull. It was the one part of the jellyfish that could not make the turn into the hose. Out it came, and full flow was restored.
Yes, some boat issues take quite a bit of time to finally resolve...
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Post by Zanshin on Apr 23, 2015 11:38:39 GMT
As an owner of a low hours, about 5 so far Cumins 6.5kva generator probably the size smaller than yours, just wondering how long your impellors last?... My impeller blades have lasted about 150 hours each, so far. As a 220V 50Hz boat the generator is chugging away at low speed. I wish the engineers would have designed the heat exchanger inlet to be more accessible, they should know by now that the generators get installed in very narrow and small places! And to design it so that the oil filter needs to be removed in order to access the end of the heat exchanger is just thoughtless. |
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Post by abgreenbank on Apr 23, 2015 12:17:55 GMT
Just wonder if it is possible to fit a strainer/ filter before the heat exchanger to collect the impellor bits .
150 hrs per impellor sounds pretty poor performance considering these onan generators should last many thousands of hours.
i guess you are getting pretty good at replacing them!!
regards
ab
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Post by sailbleu on May 9, 2015 6:28:53 GMT
Just wonder if it is possible to fit a strainer/ filter before the heat exchanger to collect the impellor bits . 150 hrs per impellor sounds pretty poor performance considering these onan generators should last many thousands of hours. i guess you are getting pretty good at replacing them!! regards ab Ab, I intend to do just that after replacing the impeller yesterday , as stated in my post of april 22. Very disturbing news when I removed the old one . 2 of the blades were gone and several others were cut and ready to break off. This impeller was in use for 2 seasons of which one was very short with a minimum of engine hours that year ( 2013 ) Last year I had more , but all in all not that much. Although it was tough to make an estimate since my engine hour meter is still out of business. I also solved that Volvo Penta problem yesterday by installing a 12 volt non-digital one. Dont seem to be able to post a picture. Regards |
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Post by rxc on May 9, 2015 15:38:15 GMT
Sailbleu,
I think you have a good idea. I am going to look at my genset configuration and see where I can install another strainer to catch impeller blades. I don't think it will cut down the flow too much, especially since it will be on the discharge side of the pump. I just have to see what the hose sizes are, and if a strainer will fit into the genset enclosure.
Regarding access, I have pretty good access to my Northern Lights unit, but I think that access problems are due to the fact that genset manufacturers use standard engines that are built for all sorts of applications, most of which do not involve the access limitations on boats. And since you really don't know where/how it is actually going to be installed, it is hard to pre-determine exactly which sides of the unit should have all the important access points. Most inboard propulsion engines have the same problems. I think that maybe the boat-builders should think about access more, for things like oil and filter changes. They do, somewhat, by providing doors, but they don't include oil drain hoses from the sump or remote filter mounts, which they could do much cheaper and easier than an owner could.
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Post by sailbleu on May 10, 2015 11:41:17 GMT
Ok , this time tinypic worked , here is the pic  I never acceed 2500 revs , exhaust elbow is completely clear , and yet this happened. Ordered a new impeller already , from now on it's an annual obligation ! Regards |
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Post by captbillh on May 10, 2015 12:14:04 GMT
Since my engine impeller is easily accessed, in the fall I remove it and put it in a ziplock bag with olive oil and relax the alternator belt.
Even then in 250hrs over 2 years a blade broke off and it was found in the tube sheet of the heat exchanger.
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Post by Damir on May 10, 2015 13:15:33 GMT
Implellers are made off the rubber, if stand long on the shelf is too old and brittle is simple.
Somethime you must have luck. Most of us have a reserve on a ship that is useless (can work a few hours - a few days if you're lucky a couple of months). Impeller must be purchased from authorized dealers who have great sales. I have 2 or 3 piece but don't kow oldest
Regards Damir
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Post by DUET on May 11, 2015 19:55:53 GMT
Interesting common problem. On my 50DS, it listed an Onan genset which I exchanged for a Northern Lights (up charge, of course). The main reason was to have the genset run at its stated 1800 rpm rather than the Onan at 3600. This increase in rpm's may or may not have any bearing on the longevity of the impeller. My impeller on the Northern Lights is difficult to access although nothing like the impeller on the Yanmar 4JH4-HTE which is almost impossible. To make life easier, I have installed the SpeedSeal Life impeller plate on both the genset and the Yanmar. Also, because the genset seemed to pick up all seaweed available, I also installed a strainer on the thru hull which can be opened with a removable pin for inspection or removal of anything that gets through. An additional strainer after the impeller seems like a good idea although I'm not sure how to do it.
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Post by Zanshin on May 12, 2015 10:49:09 GMT
Interesting common problem. On my 50DS, it listed an Onan genset which I exchanged for a Northern Lights (up charge, of course). The main reason was to have the genset run at its stated 1800 rpm rather than the Onan at 3600... Are you certain that it wasn't a Fischer-Panda in the original? I ask this because the Fischer-Panda generators run at 3600, which is why they can pack so much power in a small package. The Cummins-Onan and Northern Lights, on the other hand, run at 1800 or 1500 RPM to generate 60Hz and 50Hz respectively. I just checked my Onan manual which lists the other Onan models as well and see none that run that high. |
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Post by DUET on May 12, 2015 15:22:22 GMT
I may have been mistaken about the Onan. As with you, I purchased the 50 DS through Chris Bent and I may have misunderstood him. I did order the Northern Lights, based on lack of maintenance and the 1800 rpm specification. I did have an issue with the installation which allowed water to seep into the alternator. It required removal to repair with a fabricated drip tray to solve the problem, not at Bay Yachts (Atlantic Cruising) however. No issue with the impeller, but I'm always checking the water flow due to the previous issue with seaweed, etc.
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Post by abgreenbank on May 13, 2015 12:58:56 GMT
I have standard onan 6kva on my 50DS, it runs at 2400rpm for 50hz and around 3000rpm for 60hz and then it also produces more power. Mine a European spec 50hz and reasonably quiet.
ab
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andre
New Member
Posts: 1 
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Post by andre on Mar 18, 2016 1:50:28 GMT
I own a 2013 Jeanneau 44DS equiped with air condition on the three cabins and a Onan generator to provide enough energy to them and the boat itself. For the first maintenances the we need to do on the Onan generator the official Onan dealer have complained about the complicated access the Jeanneau as they need to work upside down to access the parts on the generator. Besides this problem mentioned above that didn’t allow us to make the proper maintenances on the Onan Generator we manage to finish them. ![]() ![]() ![]() Unfortunately, last week we found a problem the is possibly on the fuel pump located on the left side of the generator that is 3 to 5 cm from the back part of the boat. Encountering this dealer said the is impossible to reach the fuel pump from any possible access that Jeanneau has created and probably I will need to cut some part of the boat to open a new hatch to access this pump. As I can’t believe Jeanneau will make such a basic mistake I’m kindly asking you if you could guide me on how to access the fuel pump on my boat without have to cut it. Regards  |
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Post by Zanshin on Mar 18, 2016 14:24:14 GMT
It sounds like there is no easy solution, your two options are to disconnect everything from the generator and to remove it for maintenance - and then you have a choice to put in a hatch so that if that part of the generator needs to be accessed again you might not have to do all that work again.
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garrettw
Junior Member
Posts: 12
Jeanneau Model: 44DS
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Post by garrettw on Apr 5, 2016 2:16:34 GMT
I own a 2013 Jeanneau 44DS equiped with air condition on the three cabins and a Onan generator to provide enough energy to them and the boat itself. For the first maintenances the we need to do on the Onan generator the official Onan dealer have complained about the complicated access the Jeanneau as they need to work upside down to access the parts on the generator. Besides this problem mentioned above that didn’t allow us to make the proper maintenances on the Onan Generator we manage to finish them. ![]() ![]() ![]() Unfortunately, last week we found a problem the is possibly on the fuel pump located on the left side of the generator that is 3 to 5 cm from the back part of the boat. Encountering this dealer said the is impossible to reach the fuel pump from any possible access that Jeanneau has created and probably I will need to cut some part of the boat to open a new hatch to access this pump. As I can’t believe Jeanneau will make such a basic mistake I’m kindly asking you if you could guide me on how to access the fuel pump on my boat without have to cut it. Regards In my 44DS I just pull the generator forward into the cabin. Jeanneau has designed two removable sections of bulkhead to access it. You also have to remove the port side cabinetry next to the mattress. After that everything is fairly simple to get to and there is enough slack in the hoses and wires to move it around a lot. |
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Post by someday on Jul 2, 2016 15:10:02 GMT
Zanshin,
We own a 53 and met you at the Rendezvous at Peter Island. We are burning through impellers on our onan generator and would like to compare notes.
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Post by heatherina on Jul 3, 2016 3:59:28 GMT
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Post by someday on Jul 4, 2016 14:31:04 GMT
Thanks it sounds great and we will get one!
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