jramm Posted September 30, 2020 Author Report Share Posted September 30, 2020 5 hours ago, HoneyB said: I have a question but do not want to sound like a know it all or smart arse. Why in the world would u modify a water pump on a brand new motor rather than just setting it down on the jackplate? Just curious if the dealer recommended against lowering the motor, and if so why? Lol ... no worries. I appreciate all the insight and discussion. As to the mounting height, I didn’t really push (ask) the dealer about changing yet. I was more focused on prop and RPMs. I did let them know about overheat alarms and water pressure and asked them to check. They said everything checked out but not sure how much they did. My own thought on dropping a spot on the mount is that it would allow me to jack-up but wouldn’t that simple match the current level I’m at? It’s not a super huge issue but I thought I would be able to maintain a little more pressure with current setup and some lift on JP. Most of my use will not be super shallow running, but on occasion may visit areas where it would be helpful to run a little higher. Just changing the Yamaha gauge to show pressure is already helping me learn a bit as I can keep an eye on changes when I adjust. As for the mod I noted. I’m not rushing to change it out after 20 hrs, but did discover a thread on another forum related to this change. It seems to be a “common” practice by a few Yamaha shops/dealers in my area ... one even said they do the mod on all new SHOs they sell. It’s supposed to help increase and maintain water pressure and seems to be something others have been doing for years. Part of the reason I mentioned it here was to see if others where familiar. I know there are still adjustments to be made, but happy to be through the first 20 hrs getting to know the boat ... ready to focus a little more on fishing! Quote Link to comment Share on other sites More sharing options...
jh141 Posted September 30, 2020 Report Share Posted September 30, 2020 I was just looking at the water pump mod the boys at "Boat Werk of Texas" are doing. I can see the need for it on the Tunnel boats the gulf coast guys run. This is their explaination: The reason for modifying the impeller is to take the air gap out of the top of cup to make it a non prime pump. Taking the air out makes pump *** water even if you have water at lowest grate, it doesn't require full submerge to prime pump. Largest group it effects is shallow water and jack plate applications where you lift motor high to get full trim out of shallows or running super skinny with JP all the way up. On stock pump if you get top grate out of water, the pump *** air loosing prime causing cavitation and no water pumping. New SHO motors are low pressure and you will not notice much pressure on gauge as its regulated, but they also are 1 of the main pumps to cavitate even in turbulent water near lower unit. If you do this on your Pathfinder, let us know how you like it. I still maintain (I was out in the boat testing last Thursday ) that you should move the motor all the way down for best speed and performance, BUT if you could do the impeller mod and maintain good water pressure at full up on the jack plate for extended periods of time, I see that as a huge advantage crossing flats, especially in your neck of the woods. Quote Link to comment Share on other sites More sharing options...
jramm Posted September 30, 2020 Author Report Share Posted September 30, 2020 1 hour ago, jh141 said: I was just looking at the water pump mod the boys at "Boat Werk of Texas" are doing. I can see the need for it on the Tunnel boats the gulf coast guys run. This is their explaination: The reason for modifying the impeller is to take the air gap out of the top of cup to make it a non prime pump. Taking the air out makes pump *** water even if you have water at lowest grate, it doesn't require full submerge to prime pump. Largest group it effects is shallow water and jack plate applications where you lift motor high to get full trim out of shallows or running super skinny with JP all the way up. On stock pump if you get top grate out of water, the pump *** air loosing prime causing cavitation and no water pumping. New SHO motors are low pressure and you will not notice much pressure on gauge as its regulated, but they also are 1 of the main pumps to cavitate even in turbulent water near lower unit. If you do this on your Pathfinder, let us know how you like it. I still maintain (I was out in the boat testing last Thursday ) that you should move the motor all the way down for best speed and performance, BUT if you could do the impeller mod and maintain good water pressure at full up on the jack plate for extended periods of time, I see that as a huge advantage crossing flats, especially in your neck of the woods. That was the same info I found and checked into a bit. Those guys are just down the road from me. I don’t really like replacing parts that don’t need to be replaced so I might consider this in the spring as part of next maintenance interval even if that’s early for water pump. Quote Link to comment Share on other sites More sharing options...
Lap it Up Posted October 1, 2020 Report Share Posted October 1, 2020 Read up on the "mod" I will be doing it next impeller change. Thanks for the info! Quote Link to comment Share on other sites More sharing options...
Texas T Posted October 1, 2020 Report Share Posted October 1, 2020 On 9/30/2020 at 2:50 PM, jh141 said: I was just looking at the water pump mod the boys at "Boat Werk of Texas" are doing. I can see the need for it on the Tunnel boats the gulf coast guys run. This is their explaination: The reason for modifying the impeller is to take the air gap out of the top of cup to make it a non prime pump. Taking the air out makes pump *** water even if you have water at lowest grate, it doesn't require full submerge to prime pump. Largest group it effects is shallow water and jack plate applications where you lift motor high to get full trim out of shallows or running super skinny with JP all the way up. On stock pump if you get top grate out of water, the pump *** air loosing prime causing cavitation and no water pumping. New SHO motors are low pressure and you will not notice much pressure on gauge as its regulated, but they also are 1 of the main pumps to cavitate even in turbulent water near lower unit. If you do this on your Pathfinder, let us know how you like it. I still maintain (I was out in the boat testing last Thursday ) that you should move the motor all the way down for best speed and performance, BUT if you could do the impeller mod and maintain good water pressure at full up on the jack plate for extended periods of time, I see that as a huge advantage crossing flats, especially in your neck of the woods. Boat Werx of Texas Quote Link to comment Share on other sites More sharing options...
jh141 Posted October 2, 2020 Report Share Posted October 2, 2020 Yes......My bad.......Thanks for correction http://boatwerxtx.com/ Quote Link to comment Share on other sites More sharing options...
jramm Posted September 22, 2022 Author Report Share Posted September 22, 2022 Resurrecting my old thread … any chance @Lap it Up or anyone else did that impeller mod? I have not done it yet. Another tech said they do it on all the shallow water boats but wouldn’t matter on mine. I haven’t had issues in a while as I have learned the boat better but was curious if others tried this. I’m leaning more to to an ecu flash in the near future (see earlier Ricky Bobby quote.) Hope everyone is doing well. Quote Link to comment Share on other sites More sharing options...
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