Wear Ring Replacement - AKA - Transom Plate Disaster!

[AboveTheBest]

My top speed has declined from 51 down to 43 over the last couple of years, which I hasn’t really bothered me too badly (43 is still plenty fast in my book). More concerning to me is within the last two weeks my holeshot has dropped off to the point that it takes an extra second to get up behind the boat on a slalom (a second is an eternity when doing this).

In efforts to correct the issue I set off to replace the wear rings with some replaceable-liner style units I got in the mail and perform some maintenance on the impellers.

I took the pumps off the boat this morning and everything went smoothly and I used some 5200 to seal up the gaps in the intake tunnel. That stuff is nasty, but I found some serious gaps and filled them in nicely. SUCCESS

I found a couple of small dings/defects in one of the impellers and hammered them back and then filed them back down to where they looked good. SUCCESS

I put the port wear ring on, and pump back together with no problem. Then I got working on the starboard side and three of the bolts holding the wear ring to the transom plate are stripped and won’t take a bolt… FAIL

So a trip to Lowe’s and now I’m trying to drill/tap the old holes to a 12mm (up from 10mm).

I got 3/4 of the way drilling the first hole out and then my brand new bit snapped in half. I’m going back tomorrow to buy a half-dozen bits and hopefully can get this done tomorrow night.

My question is this: what are the transom plates made of? I’m assuming they’re aluminum, but if they’re stainless (God I hope not) my tap won’t work and I’ll need to buy a cobalt tap. My biggest fear is snapping a tap and then having to deal with getting it out and the re-tapping to a bigger size. Any advice on tapping would be greatly appreciated

Of course it gets worse.

We have our annual family vacation that I’m leaving for on Friday and I need to get this finished in the next day or two. I’m prepared to buy a new transom plate and pay overnight shipping if I have to, but that’s another nightmare, as the bolts holding the plate on are very difficult to get to…

 

[Cobra Jet Steering LLC]

I believe if you abandon drilling the holes and go with some standard threaded bolts and tap the holes for them you won't need to go a lot bigger I forget the sizes but lets say a 3/8ths bolt is just a bit larger than the 8mm bolt you can thread the holes to 3/8 and do it a lot easier also use some wax or grease when you are drilling or threading the aluminum.

 

[AboveTheBest]

Thanks Jeff.

I’m sitting on the patio with my wife, smoking a cigar and drinking a glass of bourbon to keep my mind off the boat (clearly not working), and I told her the first reply to my post was from the guy who’s opinion I trust the most when it comes to our boats.

I figured it was aluminum and that makes this much simpler, but after snapping that drill bit I started getting squeamish.

Hopefully tomorrow I can mark this off my list and stop worrying about it.

 

[Cobra Jet Steering LLC]

Ok just go slow and steady but look into what I said I did a lot of that with 720 sea doo engines years ago when the bolts pulled loose on the intake worked really well just find the next size up from the 8mm bolt. 10mm is way too big, real hard to drill and tap. If the bolt was 8mm I believe 5/16 standard will tap in that hole

 

[AboveTheBest]

Looks like I’ve got my work cut out for me on the tapping…

I’ve already opened up the holes on the wear ring using my drill press to take the 12mm replacements (the originals are 10mm fine 1.25).

The bit I used to prep for the tap just barely took the threads off the old opening, so I don’t think I could have gone any smaller unfortunately.

I’ll be going SLOW when I tap, and will use copious amounts of oil.

 

[AboveTheBest]

Holes drilled and tapped and the pump is back in place!
I usually don’t get anxious about things, but was pretty worried with vacation coming up at the end of the week.

Thanks for steering me in the right direction Jeff! —- see what I did there…

Now I’m eager to see if the tunnel sealing, impeller fixing, and wear ring replacement will have an effect on the speed.