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· Living in a cage of fear
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16,524 Posts
Discussion Starter · #1 ·
OK,
So I got the high dollar rebuild, JG bowl, detailed impeller (Supposed to be an "A") Place and droop.

Boat never went right compared to last year. Lots of caving and very "pipey".
Still believe there are intake angle issues, but I don't know.
Went out the other day. Ran about 20 minutes or so. Stopped and fished. Started up and boat would rev, but barely move.
Got to the trailer, pulled hand hole and could see impellor was broken.
Here it is.




Engine is estimated about 550 HP. Never sees 5500 RPM, but has hammered a few times from caving. Can cavitation cause this?
The pump, speed, and general response has been unimpressive since the whole upgrade.
 

· Living in a cage of fear
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16,524 Posts
Discussion Starter · #4 ·
Who put that pump together? I've sucked up a few rocks in my time but never seen damage like that, I'm almost afraid to comment on it. That would be some serious cavitation.

Pump has MAYBE 4 hours total on it. It turned freely before I installed it in the boat, but it came freshly assembled with all new parts. I looked inside and blew everything out before installation.

It Cavitated about 2 seconds, twice (kind of "hammered") at around 4500 RPM, 55 MPH. I never ran it that high again, although it should easily pull 5500 RPM and 70 MPH+. It ran 70 last year at 5200 with a beat up JC and no droop or diverter. It has the same basic engine but with a hydraulic roller and all forged lower end.
Like I said, it never felt right from the get go.

I want to take the boat to some one near SAC to re-assemble with a new impeller, and install the transom cover, as well as check my intake angle also.
Who is the expert near Sacramento??
 

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372 Posts
Did you have the droop on it last year? I think they take a little longer get the air out unless you have one of those prime a jet's on them, how about a loader? Could have starved it the first time it cavitated and then when it hooked again that was that.
 

· Living in a cage of fear
Joined
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16,524 Posts
Discussion Starter · #6 ·
Did you have the droop on it last year? I think they take a little longer get the air out unless you have one of those prime a jet's on them, how about a loader? Could have starved it the first time it cavitated and then when it hooked again that was that.
No droop last year, no loader. It did take some time to prime, but it is a no wake zone for a good 10 minutes where we launch at Shasta. I always ease into it at first just to avoid that.
All I know is that I got to get it fixed!! I've never installed an impeller, but have built every other square inch of this boat it seems.
I am contemplating changing it out myself.
Any jet guys around Redding that can give me sound advice while watching me work and drinking all my beer??:)bulb:)bulb
 

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372 Posts
No reason you can't do it yourself, especially with help from the folks here on the boards. Call Tom at Jet Boat Performance, he posts on the boards, he will be happy to assist you with questions, tech help, and a new impeller and wear ring. Get a loader also before you go back out.
 

· Living in a cage of fear
Joined
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16,524 Posts
Discussion Starter · #9 ·
No reason you can't do it yourself, especially with help from the folks here on the boards. Call Tom at Jet Boat Performance, he posts on the boards, he will be happy to assist you with questions, tech help, and a new impeller and wear ring. Get a loader also before you go back out.

I just tried to call him, no answer but left a message.
Going to go out and attempt to remove impeller.
 

· Living in a cage of fear
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16,524 Posts
Discussion Starter · #11 ·
Thanks Tom, just got your' PM.
Well, pulling the impeller was a snap. 2 pipe wrenches and a gear puller. Off in 5 minutes.
Here it is.
Note the wear ring surface. Totaled. Wear ring looks about the same. Appears to be a plastic liner behind wear ring?


 

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372 Posts
How does the bowl and the suction housing look? For the moment I'd put the bowl back on and see if there is any up and down play with the shaft, if you can have someone turn the engine over slowly (as in with a breaker bar) you can also check to make sure the shaft isn't bent.
 

· Living in a cage of fear
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16,524 Posts
Discussion Starter · #14 ·

· JRPM/e-PerformanceMarine
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1,458 Posts
This season I have seen two real bad pumps. Both were due to Thrust Bearing failure, improper maintenance. Both destroyed the impeller and mains/crank of the engine. Grease your pumps before you put them away folks, it will save you some money and keep you on the water.

Sorry to hear about your pump. I have a good used one in the spam section that will get you by while you have one built. It is item #32, http://www.performanceboats.com//showthread.php?t=38574
 

· JRPM/e-PerformanceMarine
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1,458 Posts
Jim are you meaning the bearing here ?
Yes Tom I am, I know that this damage is not due to a bad Thrust bearing but my words may save some others from future damage. It sure looks like alot of this went bad.

I have a customer that was cruising up river, running about 40mph. He did not see the rock bar just north of Big Bend State Park out here. The impact was so great it killed the engine and tried to rip out the loader. They had each and every vain of the impeller loaded with rocks. The bowl had minor damage as well from a few rocks that got past the impeller. They are just lucky the boat was not damaged or anyone hurt.
 
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