Jet Boat Impeller/housing Repair

[guythatbrews]

My across the street neighbor has an old Sea Ray jet boat. The impeller/housing is worn out so he's looking for a repair. This is NOT a money maker. We do each other favors turn and turn about so I don't mind, even though I'll probably spend a bunch of time on this.

The aluminum housing is too worn to get sufficient jet to drive the boat. The impeller is SS and he has worked it over so it is likely smaller than stock. The housing might be welded up but with that much weld the distortion on the remaining features will be horrible. Maybe spray weld but I don't have a vendor. He says he can get some sort of plastic insert made for the purpose. Bore the housing and insert the liner. Liner is supposed to be 6mm thick and hopefully the liner vendor will supply the housing bore size. Our lakes are not sandy so a plastic insert should last a while and can be replaced, so maybe not a bad option. If I had a piece of tube the right size I'd just loctite a sleeve in place, but I've none and short pieces of tube just the right size are hard to come by for free/cheap.

My guess is the bore and the impeller are simply cylinders with a close gap. So I'd bore the housing, install the liner, maybe bore the liner, and turn the impeller to fit.

Can anyone confirm these are true cylinders? Anyone done this or have a better repair method? Any idea of appropriate gap size?

Again, just a favor for a buddy and not a money deal. In general I don't do repair work.

 

[BT Fabrication]

the housing isnt worn out, the blades are.
bronze blades at the leading edge has like 1/4" gap
probably need to weld the blades back up or get a new one, or recast it all.

 

[Bill D]

I doubt any pump has a straight parallel bore. I would assume it has a tapered intake and outlet. Possible for an few inches, the thickness of the impeller, it is a straight cylinder.
Do they sell larger impellers to fit worn bores like for engines?
Bill D

 

[guythatbrews]

the housing isnt worn out, the blades are.
bronze blades at the leading edge has like 1/4" gap
probably need to weld the blades back up or get a new one, or recast it all.

I assure you the housing is very worn. The impeller is SS, not bronze. This particular assembly fits close and does not have a 1/4" gap. Maybe there is more than one design.

But of course! Weld up the blades and turn down. That does seem very doable. A little oversize on the impeller and bore the housing to fit.

 

[BT Fabrication]

as said above, the bore isn't straight. its tapered cone ish shape. you can see the lines in it still. and the bore isnt very worn, the impeller is..... the bore looks to only have minor wear. couple grooves could be welded and blended back in smooth for the couple small areas.
impellers usually wear as they are cutting through the water, the mass area of the housing gets much less wear.

 

[guythatbrews]

Thanks for the replies thus far.

I neglected to mention buddy says there is an intake screen but you can stick your thumb through it. He got in some shallows and crap got drug through the housing. He used devcon and got a useable repair but it only lasted a season. The boat is a 1991 so it's seen some use.

 

[gbent]

If he got one season out of devcon, a repair with a ceramic filled polymer such as one of the abrasion resistant grades of Belzona will last longer than the boat.

 

[Hodge]

What brand of jet drive? Are housings available

 

[guythatbrews]

What brand of jet drive? Are housings available

Don't know the brand. Housings can be had but over $500.

 

[henrya]

It does not look like any Outboard Jet brand pump to me but it might be because they seem to be the makers of nearly all outboard jet pumps. They have great customer service. Look them up and call them. They have parts for older pumps, so give that a try. A new liner from them is not expensive. And after all, its a boat so its just pouring money down a rat hole anyway.

 

[Bill D]

It does not look like any Outboard Jet brand pump to me \

What makes you think it is an outboard pump? I seldom see those here. Lots of inboard pumps seen.
Bill D

 

[SIP6A]

The boat is a 1991 so it's seen some use.

That's 31 years old, maybe it time to think about a new / newer jet ski.

 

[CarbideBob]

That's 31 years old, maybe it time to think about a new / newer jet ski.

That is not old. Mine is a 1969.
Different pump and has a replaceable wear ring available in various undersizes in .005 increments.

 

[guythatbrews]

That's 31 years old, maybe it time to think about a new / newer jet ski.

This guy is a drive it forever guy. He's a much more-than-average mechanic.

That is not old. Mine is a 1969.
Different pump and has a replaceable wear ring available in various undersizes in .005 increments.

Your's is undeniably long in the tooth. It takes tlc to keep a boat afloat that long!

In my meaderings I've seen the replacement sleeves, both plastic and SS. This housing is not set up for this and might not be thick enough to bore for a sleeve.

There is also talk about endwise impeller shimming to reduce clearance. Consensus is around .015 clearance is good but .035 is too much. So, as folks have said, the housing is slightly tapered. How much? Maybe the taper is solely to allow shimming and has nought to do with propulsion.

 

[Fish On]

It does not look like any Outboard Jet brand pump to me but it might be because they seem to be the makers of nearly all outboard jet pumps. They have great customer service. Look them up and call them. They have parts for older pumps, so give that a try. A new liner from them is not expensive. And after all, its a boat so its just pouring money down a rat hole anyway.

Definitely not an outboard jet.

I'm pretty sure that's one of the old low hp Mercury Sport jets. The 90 or 120. Inboard jet pump, but instead of the engine being in front of the pump, it's on top with a 90 degree gear drive.

I've never done any work to the actual engines and pumps on those (just some of the aluminum hulls they're in), but my understanding is that on the small ones, at least, the housing is the liner, there's no removable liner. Also, the parts breakdown doesn't show the stack of shims I'd expect with a tapered liner, so it may well be straight.

 

[CarbideBob]

Your's is undeniably long in the tooth. It takes tlc to keep a boat afloat that long!

Yes someday I will have to admit that I am getting old.
The wife likes the old (1978) pontoon much better with a 35hp motor and does so much care for it.
Me, fire up that 428 Ford cobra jet in a 15 foot boat and I feel alive and 20's again just from the sound. But... after 15 minutes it is sort of boring as she will only run 78mph.
Super tight clearance (.005 or less) on most jet pumps is crucial to performance and the win or fastest boat on the lake.

 

[John Garner]

If he got one season out of devcon, a repair with a ceramic filled polymer such as one of the abrasion resistant grades of Belzona will last longer than the boat.

The name "Devcon" is as non-specific as "Lubriplate". Both are company names, and both companies make many different products that have different purposes.

Devcon has offered wear-resistant ceramic-filled epoxies for decades, intended to survive abrasive scouring.

 

[guythatbrews]

Problem is any specialized epoxy coating is cost prohibitive and more work for me. Maybe if I had something correct on the shelf I might do it, but I don't.

So far my best option is to bore the housing until cleanup, and weld up the impeller and turn it to fit the housing.

Best I can tell some of these housings are straight bored and some are taper bored. This one appears to be straight. So a few hours work tops and it is fixed.

Maybe if I'm still around when it wears out again then I can use Devcon.

 

[henrya]

What makes you think it is an outboard pump? I seldom see those here. Lots of inboard pumps seen.
Bill D

Here in middle America I’ve not seen hardly any inboard jet drives, but plenty of jet outboards. I even own one. The OP is from the middle of the country too. I bet jet inboards are fairly rare there too.

 

[EmGo]

Here in middle America I’ve not seen hardly any inboard jet drives,

They are popular for ski boats in northern california. Bikini-clad bimbo and an outboard ? That's a flat no. You need enough chrome to poison an entire village and a radio that'll wake the dead or they'll laugh you right off the lake.