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Old 06-30-2012, 04:21 PM   #1
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Orientation of Raw Water Pump, Ford Lehman

OK, This might seem like a silly question but I have to ask. I am replacing the original raw water pump on my 120. The new Johnson pump has a plate that shows rotation in both directions. I understand this depends on the engine rotation. Looking at the faceplate from the back of the engine, the water ports face 11 o'clock and 7 o'clock. Based on the placement of the oil cooler, the top port, 11 o'clock, should connect to the oil cooler and the bottom port, 7 o'clock, should connect to the raw water intake strainer. Does this sound correct for the new replacement pump? The original pump was U shape. Chuck
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Old 06-30-2012, 09:23 PM   #2
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I know you prbably already know most of this...but maybe it will help you visualize your pump better...

It's cut and paste from the Sherwood pump site...different manufacturer but maybe it will help anyway...


One frequently asked question is which port is the inlet and which is the outlet. Most Sherwood rubber impeller pumps are bidirectional, so the rotation of the engine and the orientation of the pump mount will determine which port is which.
In general there is a cam screw between the ports. That screw holds the cam in place; the function of the cam is to squeeze the impeller as it rotates over it. As the impeller moves away from the cam, the impeller blades open up and water is ingested in the pump (pump INLET). As the impeller approaches the cam and becomes compressed, the water is forced out of the pump (pump OUTLET).
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Old 07-01-2012, 01:06 AM   #3
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I went thru this a couple of years ago. I wasn't adventurous to tackle the job myself, and had our local boat mechanic ( a pretty good guy, knowledgeable, etc) but after he replaced the pump I lit up the engine.. no water passing out the exhaust... but a gurgling coming up where the raw water intake is located. Yep.... plumbed backwards. The pump was rotating properly... but the hoses were backwards. He switched the input/output hoses and it's run great ever since.
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Old 07-01-2012, 03:35 AM   #4
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We had the Johnson pumps installed on our FL120s a number of years ago. The raw water input is the bottom port, the raw water output (which goes first to the oil heat exchanger) is the top port.

NOTE: When the Johnson pump is mounted it makes for very tight quarters changing the injection pump oil because the upper (output) elbow and hose is right under the injection pump drain plug with very little clearance. There are two solutions----

1. Cant the pump so the upper hose is inboard next to the block. This will provide a little more room to get at the injection pump drain plug. The pump doesn't care which way it's oriented so canting it inboard a bit doesn't affect the pump's operation at all.

2. Come up with a way to drain the oil without canting the pump. This is what we did. I came up with a simple hose and bottle system for catching the oil coming out of the drain hole and feeding it into a bottle. So pump oil changes are now no more difficult or time-consuming than they were with the old Lehman/Jabsco stock raw water pump and drive coupler.
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Old 07-01-2012, 11:15 AM   #5
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Thanks Marin, So it sounds like my install is correct. I have rigged a plastic bottle to fit the oil drain as you have and it will work just fine. Now I have to try and get the nuts loose to swap out the fuel pump. Chuck
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Old 07-01-2012, 03:39 PM   #6
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You may find you need to acquire a very thin wrench like an ignition or tappet wrench or grind down a conventional wrench to fit it into the very tight space where one of the fuel pump mounting fasteners is. Also, depending on the fuel hose install, you may need a thin wrench there, too, to get the hose fitting off the pump.
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