A month or so ago I was poking around the Yanmar 4JH4E engine on our 2007 H41AC and I found what looked like evidence of leakage on the underside of the raw water pump around the weep holes (see the "before" photo). The engine has about 1400 hours on it. I removed the pump from the engine and took it to my shop to disassemble it and I found that the V-ring and the mechanical shaft seal were substantially deteriorated. The pump shaft had deposits on it but it looked like it might clean up with Scotch-Brite (it did).
I searched the web to see if I could find a service kit for the pump which, by the way, is manufactured by Johnson Pump. Their number for the pump is 10-13328 with a suffix of -01, -02, -03 or -04 depending on the impeller style (non-threaded or threaded) and the outlet fitting style (straight or ell). I attached the Johnson Pump drawing for the pump as a PDF.
Not finding a service kit with genuine parts, I compiled a spreadsheet for the parts needed for rebuilding (attached as a PDF). I ended up ordering most of the parts from pumpagents.com, using the Johnson Pump part numbers, but I found later that Fisheries Supply has many of the parts at a lower price (some are special order, however). I got a pair of Timken 6203-2RS bearings on Amazon for about $11. (As an aside, this happens to be exactly the same bearing that I used for the serpentine belt idler pulley that I recently fabricated.) The rubber seals need to be removed from these bearings before installation but you can also find the "open" style which has no seals. If you would like the actual spreadsheet, it can be retrieved from my website using the URL below.
Disassembly of the pump is fairly easy. Although a press makes the process simpler it can be accomplished without one. Because the two bearings are so closely spaced a bearing splitter is nearly essential and certainly makes it much easier to separate the bearings. Note that the retaining ring that sits just behind the rear wear plate is a bronze alloy and it will likely get distorted during removal and would need to be replaced. After disassembly, I sand blasted the housing and then washed it in solvent.
The reassembly process is fairly straightforward, the primary issue being the orientation of the V-ring seal and the components of the mechanical seal. If you observe carefully while disassembling the orientation will be clear. A photo of the finished pump is attached. By the way, the mechanical shaft seal has two parts and Yanmar has separate part numbers for each but Johnson Pump has one part number for the set.
There is a YouTube video of rebuilding one of these pumps. It is in Greek with no closed captions but watching it does help in understanding the process.
Lastly, my research suggests that this pump is used on the following Yanmar engines (and possibly others):
3JH4, 3JH5, 4JH4, 4JH5, 4JH5E, 3JH4E, 4JH4E, 4JH4AE, 3JH5E, 4JH45, 4JH57, 4JH80
To confirm, check the parts manual for your engine and see if the part numbers match up with those in my spreadsheet. When doing this, be advised that quite a few of the Yanmar part numbers listed in the parts manual that I have for the 4JH4E have been superseded by the numbers shown in my spreadsheet. You can verify the verify the part number by going to the website of a supplier like Toad Marine Supply and keying in a part number in your parts manual. If that part number has been superseded that site will give you the new part number.
I searched the web to see if I could find a service kit for the pump which, by the way, is manufactured by Johnson Pump. Their number for the pump is 10-13328 with a suffix of -01, -02, -03 or -04 depending on the impeller style (non-threaded or threaded) and the outlet fitting style (straight or ell). I attached the Johnson Pump drawing for the pump as a PDF.
Not finding a service kit with genuine parts, I compiled a spreadsheet for the parts needed for rebuilding (attached as a PDF). I ended up ordering most of the parts from pumpagents.com, using the Johnson Pump part numbers, but I found later that Fisheries Supply has many of the parts at a lower price (some are special order, however). I got a pair of Timken 6203-2RS bearings on Amazon for about $11. (As an aside, this happens to be exactly the same bearing that I used for the serpentine belt idler pulley that I recently fabricated.) The rubber seals need to be removed from these bearings before installation but you can also find the "open" style which has no seals. If you would like the actual spreadsheet, it can be retrieved from my website using the URL below.
Disassembly of the pump is fairly easy. Although a press makes the process simpler it can be accomplished without one. Because the two bearings are so closely spaced a bearing splitter is nearly essential and certainly makes it much easier to separate the bearings. Note that the retaining ring that sits just behind the rear wear plate is a bronze alloy and it will likely get distorted during removal and would need to be replaced. After disassembly, I sand blasted the housing and then washed it in solvent.
The reassembly process is fairly straightforward, the primary issue being the orientation of the V-ring seal and the components of the mechanical seal. If you observe carefully while disassembling the orientation will be clear. A photo of the finished pump is attached. By the way, the mechanical shaft seal has two parts and Yanmar has separate part numbers for each but Johnson Pump has one part number for the set.
There is a YouTube video of rebuilding one of these pumps. It is in Greek with no closed captions but watching it does help in understanding the process.
Lastly, my research suggests that this pump is used on the following Yanmar engines (and possibly others):
3JH4, 3JH5, 4JH4, 4JH5, 4JH5E, 3JH4E, 4JH4E, 4JH4AE, 3JH5E, 4JH45, 4JH57, 4JH80
To confirm, check the parts manual for your engine and see if the part numbers match up with those in my spreadsheet. When doing this, be advised that quite a few of the Yanmar part numbers listed in the parts manual that I have for the 4JH4E have been superseded by the numbers shown in my spreadsheet. You can verify the verify the part number by going to the website of a supplier like Toad Marine Supply and keying in a part number in your parts manual. If that part number has been superseded that site will give you the new part number.
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