New to forum, new to jet boats...now to rebuild it

[2000challenger]

Hello all! Over the past 2 days I have been browsing all 26 pages in this forum and wow, what some great information. I just purchased a 2000 model challenger 2000 on a trailer for $750 (950 once i busted 2 tires on the 120mi trip home :facepalm: )with a mercury 240 efi that is in 3 large boxes... Tore down the owner had his mechanic look at it and it looks as though the oiler gear went out.. One Pistons bottom tore off and really banged up the bottom of that cylinder and the two cylinders across from it.. Causing some fractures in the bottoms of those cylinder... The crank also has some strange damage on it... Wear on only one side of where the one of the carrier bearings run. My question is should I rebuild it or could I look for an older 2.5l mercury outboard powerhead that might fit? What might be most economical? I am familiar with rebuilding mid-90s yamaha and seadoo engines but this looks to be a beast of a different color. Thanks for the help! WiLl try to post pics later

 

[LouDoo]

Hi and welcome to the SeaDoo forum. Well this sounds like a job for the Doctor, he usually checks in a couple of times a day. [MENTION=16022]Dr Honda[/MENTION]

Lou

 

[2000challenger]

That would be great! I have read a lot of his posts and seems like he knows the merc. 240 better than the engineers who designed it I am updating my iPod right now so I can post pics (I am one of those people from the stone age that STILL don't have a smart phone ;O ! )

 

[2000challenger]

this is a shot of the boat... Needs new seat covers and a buff.... And most importantly.. The power source

damaged cylinder.

fracture on opposite cylinder...

crank damage. What y'all think is it fixable? If so can I just take it to a local machine shop?


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[2000challenger]

pick of where pieces of piston fell down on crank and beat up the case ( and what caused that large stress fracture in bottom of cylinder in 3rd pic


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[Dr Honda]

Hummmm.



Yep... rebuildable.


Crank: It's ugly, but there are shops that can weld up that journal, and regrind it. Marine Crankshaft is who I used. They have been around for a while. They welded up 4 of my journals, fixed the lower seal surface, polished, and rehardened it. It was $500 with shipping.


Engine Case: Believe it or not... that crack in the bottom of the cyl is superficial. Some one with a TIG welder can fuse that together in about 30 seconds. Heck... it would probably be fine as is. (as long as you can't see thought it) In a 2-stroke... the case has to be air tight, so you don't loose air/fuel mix to another cyl or out of the engine.

CYL's: I would hit the rough cyl with a hone, and check for roundness, and size. It may clean up, and you can throw in a new piston. If it's too rough, have it bored out one size over.


MISC: I would check over all the rods, and make sure they are OK.

As far as finding a 2.5L outboard... it won't work. From my understanding... the splines on the crank from the SportJet, to the Outboards are different.

 

[2000challenger]

I am planning on bringing the crank and block to a machine shop tomorrow... Is there any special process that they will have to use to properly build, grind, and properly re-harden the crank (I want to be able to ask what they are going to and know if they are using the correct process). I also have Been looking at rebuild kits on eBay which one should I get? Any brands of pistons better than the next? ( sorry for all the questions... Just out of my element


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[2000challenger]

Soooooo glad to hear that on the block!!!!!!!!!!!!


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[2000challenger]

What should I look for on the rods? His is a pic of the one on the bad cylinder.. It was hitting the block

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