Colindarling
Active Member
- Messages
- 6
- Reaction score
- 5
- Points
- 42
- Boat Make
- Yamaha
- Year
- 2021
- Boat Model
- Limited S
- Boat Length
- 19
TL;DR Version:
Added plumber’s putty to the interior wall of the clean-out port plug (manhole cover) and improved the impeller seal. Fixed an otherwise undiagnosable cavitation issue. Ordered a new plug to finalize the solution.
Longer Version:
A few weeks ago, we put our boat in the water for the first time this season. While pulling a tube and wakeboarders, we experienced significant cavitation. The impeller felt like it was slipping, creating a slingshot effect—symptoms that were new to us. We were confident we didn’t hit anything last fall, but we couldn’t be sure.
We took the boat to the dealership where we bought it brand new in 2021. Initially, they said, “Nothing is wrong; you can pick up the boat.” We sent them videos showing the engine revving high when trying to lift a wakeboarder from a dead stop. The dealer claimed they couldn’t hear anything in the video (though the noise was quite evident). After some insistence, they supposedly tested it in the water but found nothing wrong. Their final suggestion was, “We can replace the impeller and impeller housing, but we aren’t confident that will fix your issue.”
After reading posts on this forum, I took the following steps:
1. Inspected the Impeller: Removed and checked the impeller—no issues found.
2. Resealed the Intake Grate: Did this while the impeller and shaft were out.
Despite these efforts, there was only a 10% improvement, far from what was needed to pull anyone on a wakeboard or tube.
I came across more posts here and started focusing on the clean-out port plug. With the boat out of the water, I poured water into the clean-out port with the plug in place. I observed a steady trickle under the boat, indicating water was leaking past the plug. My hypothesis: if water could leak out without impeller suction, air must be getting sucked in on the low-pressure side, causing cavitation.
I removed the plug and packed the gasket with plumber’s putty. I didn’t want to apply more sealer to the plug sleeve or the lip at the bottom near the intake grate and impeller, thinking if this worked, I’d get a new plug or rebuild kit. After re-inserting the plug with a tighter fit, I poured more water on top—this time, no water leaked past.
Back at the lake, the cavitation was almost completely gone (90% improvement). I’ve now ordered a new clean-out plug.
I’m sharing this because my experience with the local Yamaha dealer left me with little confidence in them and in Yamaha. Thanks to this forum’s posts and advice, I regained that confidence. I hope this helps someone else resolve a similar issue faster. I’m relieved I didn’t replace the impeller and sleeve unnecessarily for what turned out to be a bad seal on the clean-out port.
Added plumber’s putty to the interior wall of the clean-out port plug (manhole cover) and improved the impeller seal. Fixed an otherwise undiagnosable cavitation issue. Ordered a new plug to finalize the solution.
Longer Version:
A few weeks ago, we put our boat in the water for the first time this season. While pulling a tube and wakeboarders, we experienced significant cavitation. The impeller felt like it was slipping, creating a slingshot effect—symptoms that were new to us. We were confident we didn’t hit anything last fall, but we couldn’t be sure.
We took the boat to the dealership where we bought it brand new in 2021. Initially, they said, “Nothing is wrong; you can pick up the boat.” We sent them videos showing the engine revving high when trying to lift a wakeboarder from a dead stop. The dealer claimed they couldn’t hear anything in the video (though the noise was quite evident). After some insistence, they supposedly tested it in the water but found nothing wrong. Their final suggestion was, “We can replace the impeller and impeller housing, but we aren’t confident that will fix your issue.”
After reading posts on this forum, I took the following steps:
1. Inspected the Impeller: Removed and checked the impeller—no issues found.
2. Resealed the Intake Grate: Did this while the impeller and shaft were out.
Despite these efforts, there was only a 10% improvement, far from what was needed to pull anyone on a wakeboard or tube.
I came across more posts here and started focusing on the clean-out port plug. With the boat out of the water, I poured water into the clean-out port with the plug in place. I observed a steady trickle under the boat, indicating water was leaking past the plug. My hypothesis: if water could leak out without impeller suction, air must be getting sucked in on the low-pressure side, causing cavitation.
I removed the plug and packed the gasket with plumber’s putty. I didn’t want to apply more sealer to the plug sleeve or the lip at the bottom near the intake grate and impeller, thinking if this worked, I’d get a new plug or rebuild kit. After re-inserting the plug with a tighter fit, I poured more water on top—this time, no water leaked past.
Back at the lake, the cavitation was almost completely gone (90% improvement). I’ve now ordered a new clean-out plug.
I’m sharing this because my experience with the local Yamaha dealer left me with little confidence in them and in Yamaha. Thanks to this forum’s posts and advice, I regained that confidence. I hope this helps someone else resolve a similar issue faster. I’m relieved I didn’t replace the impeller and sleeve unnecessarily for what turned out to be a bad seal on the clean-out port.
