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OUV11112
RO# 28921
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 Posted - May 07 2012 : 15:13:27
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I was just doing some maintenance and was replacing the impeller on the seawater side. It had one spline broken off. What order and how should I go about trying to find it?
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Homeport: Port Dover, Ontario
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TheoMD
RO# 15854
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Posted - May 07 2012 : 19:17:25
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Fresh or raw water cooled??? On my 8.1 giBF the first stop for any impeller blade is the entrance to the heat exchanger. Remove the hose feeding the raw water to the heat exchanger and sweep with your finger to remove. If that can't be done can usually remove the end of the heat exchanger. May need to replace O ring on the end cap.
If raw water cooled the vane could be along the path of the raw water. Follow from inital entry point. Make sure in either case that you get all parts of the impeller vane.
Hope this helps
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Edited by - TheoMD on May 07 2012 19:17:45 |
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Homeport: Cotuit, MA
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OUV11112
RO# 28921
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Posted - May 08 2012 : 14:05:23
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Fresh water cooled so I will follow the path from the entry.
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Homeport: Port Dover, Ontario
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TheoMD
RO# 15854
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Posted - May 08 2012 : 16:45:15
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Yes in a FWC system I would expect that you would find that vane at the entry of the raw water into the heat exchanger as noted above. Really cannot get any further than that unless in was macerated into tiny pieces.
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Homeport: Cotuit, MA
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CurrentSea
RO# 10265
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Posted - May 08 2012 : 16:56:47
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If you need to pull the end caps off you might as well clean it up and flush it.
I did this on my old boat with Horizons.
Lots of junk came out.
Boat ran alot cooler after I did it.
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2009 Regal 4080
Volvo Diesel IPS |
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Homeport: Anchorage YC - Lindenhurst, NY
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OUV11112
RO# 28921
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Posted - May 09 2012 : 08:23:20
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Thanks for the suggestions. On a side note the impeller was $58.29 + tax here in Ontario. $45.00 in the USA.
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Homeport: Port Dover, Ontario
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CurrentSea
RO# 10265
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Posted - May 09 2012 : 08:54:44
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I carry spares of that in my Regal.
That is one of those items you want in your spare box.
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2009 Regal 4080
Volvo Diesel IPS |
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Homeport: Anchorage YC - Lindenhurst, NY
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OUV11112
RO# 28921
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Posted - May 14 2012 : 13:21:45
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I have spares on board from whe I changed them last yeae.
The spline was in the front of the oil cooler. It could get past there so it was an easy find.
Can someone explain to me how exactly this heat exchanger works.I had thought that there would be an outer jacket that the sea water circulated in and the fresh water would be circulated on the inside of this jacket. My heat exchanger had three chambers each of equal size looking down at it from the top.
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Homeport: Port Dover, Ontario
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starfishkiller
RO# 16333
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Posted - May 15 2012 : 11:12:53
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The heat exchanger is typically a large cylinder, on the order of 5" or so in diameter. Within the large cylinder are smaller tube, on the order of 1/4" in diamter. There may be about 100 or so of these smaller tubes. The smaller tubes go through a bulkhead on each end, that is about an inch or so in from each end of the cylinder. The bulkheads are brazed to the inside of the larger cylinder, and also to the ends of each individual tube. The space in the large cylinder between the two bulkheads is where the engine coolant flows, and is isolated from the ends of the cylinder, and the insides of the tubing.
Raw water is passed into one end of the large cylinder, goes through all the smaller tubes, and exits at the opposite end. That is called a one pass heat exchanger. However, most heat exchangers are multi pass, for greater efficiency. What is typically done is the circular pattern of smaller tubes, as viewed from the end, is divided into three pie shaped pieces. This would create a three pass exchanger. The raw water enters the end of the large cylinder, and can only pass through one third of the tubes. On the opposite end of the large cylinder, the water exits the first third of the tubes, and is directed to the second third of tubes. The water passes to the starting end of the large cylinder, where it is directed to the final third of the tubes, and exits at the oppposite end. Hence the water made three passes through the exchanger, picking up additional heat on each pass before exiting.
When removing the end caps on the ends of the heat exchanger you can see the small tubes, and the walls that segregate the tube pattern into three sections, assuming it is a three pass exchanger.
Hope that helps.
eric
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Homeport: Budd Lake, NJ
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OUV11112
RO# 28921
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Posted - May 15 2012 : 13:41:39
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Thanks Eric. Great explanation.
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Homeport: Port Dover, Ontario
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VP 8.1GXiID impeller spline broken
