New to jets Jacuzzi needing a rebuild?

[Redeye1620]

I am the new owner of a Jacuzzi jet powered by a 455 olds. Not being familiar with the Jacuzzi drive, I think I may have a problem. Under power there seems to be more water flowing around the nozzle of the jet than thru it. Is this an indication of the jet drive needing a rebuild? Thanks in advance for your expertise....-Rich

[Last Mohican]

Is it a YJ or a WJ?

[Redeye1620]

Is it a YJ or a WJ?

I spoke to a guy here in Northern California that has been repairing Jets for over 30 years. He told me my Jacuzzi, (YJ) is an old design & not sealed where the steering nozzle sits in the bowl. What I have happening is normal for that Jet Drive. To correct the old design I need to add a engerizer kit, $2000+ & to trim the boat another $1500 for a place diverter on the nozzle. This is more than I paid for the whole boat. BTW the hull is a 1976 Thunderbolt 21' daycruiser made right here in Sacramento.

My next step is to do a compression check on the engine & see where I might find some heads. I have two exhaust leaks, both in the center of each head. The PO over tightened the bolts & broke the hump where the top center exhaust manifold bolts are screwed into the head.

[Last Mohican]

I have a 25' day cruiser with a Jacuzzi YJ. At one time I had a converted YJ with an energizer kit & Place diverter installed in the boat. It now has the stock pump back in it. The low speed off plane manuvering is much more responsive with the stock pump. The boat gets on plane much quicker with the stock YJ. I did not gain any top speed with the converted pump. I do miss the adjustable trim from the converted pump but all things considered I prefer the stock YJ in my 25' boat. The smaller boat is a different story. I prefer the converted pump in my 19' boat.

The YJ was built to be a stump puller. It works very well getting bigger heavier boats up on plane quickly. The YJ limit is around 5000 RPM and 60 MPH. It starts to cavitate after that. There are many other factors that affect this as well.

What are your ultimate goals for the boat? and post some pictures of it!!!!

[Redeye1620]

What are your ultimate goals for the boat? and post some pictures of it!!!!

The goal is to have a dependable, reliable fun boat. I'm planning on using it mainly to pull my grand kids on tubes & wake board. Currently the engine spins at 3800-4000 rpms. I'm thinking it's getting up around 40 mph. The plan is to do an engine rebuild over the winter. Reading like crazy on 455 olds engine rebuilds.

[Last Mohican]

Send me a PM with your email address. I have a PDF copy of Tim Jurincie's Practicle Olds article. It is the go to article for rebuilding an Olds motor for a jet boat. Because of the open cooling system and sustained higher RPM there are some things you will want to do differently for a boat motor build.

My big cruiser GPSd at 39 MPH. I checked it with both the converted and non converted pumps. My Rebel GPSd 60 MPH. Again I checked it with converted and non converted pumps. I believe there was some left in the smaller boat with the converted pump. The cruiser has a wore out 455 Olds motor, the Rebel has a fresh, mildly built 400 Pontiac. The weigh difference in the 2 boats is huge. I would bet with a fresh motor and the Stock YJ, that boat will do everything you are saying you want to do.

The YJ is a very simple, reliable pump. It is great for it's intended purpose. It is when you try to push it past the intended purpose that it does not perform well. For a mild build (400 - 450 HP) and 60 MPH or less it does just fine. The YJ is also much better at digesting sand and debris than a mixed flow pump (Berkeley).

Matt