Help! Cavitation issue - 2021 AR195

[teisenhart]

Long time follower, first time posting! Little background, end of last season I sucked up a bunch of sea grass and apparently a shell. First time out this season and I was not able to get above 13mph. Checked to make sure the clean out plug was seated correctly and nothing was lodged in there, it was fine. When I inspected the the pump, I did find a shell in the housing. After removing the shell, I was able to get the boat to go up 48mph however it seems like I’m experiencing some cavitation or possibly bearing issue? It seems like it takes longer to accelerate and doesn’t sound right to me.

I shined a flashlight through the intake grate and felt the impeller. I didn’t fell anything that I thought was too rough or chipped but I’m starting to think the gap between impeller and wear ring is too much. I’ll have to pick up a feeler gauge tomorrow to measure the gap. Are the stock wear rings stainless steel? If so, do I need the whole impeller housing with another stainless wear ring? Best place to order these parts? I read that only buy OEM parts.

I started removing the pump today to inspect further but had to stop because of t-storm. If I find anything else while the pump is completely out, I’ll update! I’m assuming I have to take off the 4 Allen key bolts for the articulating keel in order to pull the pump housing with spline?

Any advice is greatly appreciated!

 

[2kwik4u]

I've not worked on the 160mm pump the 195's have, only the 155mm pump in my 190. However, I don't think they are absurdly different from each other.

That gap between impeller and housing looks a "little" big, but not terribly bad. Feeler gages will confirm, and I think the spec is in the service manual (I'll have to find mine to check). From there, if you need a new liner, I have heard that the plastic aftermarket ones are much quieter than the stainless OEM ones, however they do absorb moisture, so if you keep the boat slipped they might not be the best solution. I've never personally replaced one, so I'm unsure on that process.

Second thing to check is the tunnel sealing. There are many reports of cavitation coming from loose silicone in the tunnel between the intake and the impeller housing. I had a few leaks in mine, but no exposed/loose sealant. When I resealed the tunnel it made a significant difference in cavitation. It's an inexpensive endeavor and only requires an hour or so.

Finally, if those don't get your answers, then the Lucky 13 cone (or a competitor) might be a good answer for you. Lots of threads on that, however it doesn't address the "It was fine before" portion of the problem, it's just a solution to the symptom, not a cure for the cause.

 

[Hoyt]

Little late to this thread, but your gap between impeller and wear ring is definitely the problem. They need to be replaced. I did this same issue with my boat (Damn shells). Here's the fix....

https://jetboaters.net/threads/2019-yamaha-195-impeller-replacement.37855/#post-608567