Seadoo challenger 240 efi rebuild

[Rickdug]

Hi guys,
I just picked up my new seadoo challenger jetboat it is a project with seized engine and hopefully have payed accordingly.

I got her back tuesday night and got to work yesterday, after realising it is fully seized pulled the engine to find 1 cylinder seized, but the crank also. It has been sat fir a year and i imagine must of taken on some water via the exhaust on its last use (perhaps a sink)

Either way it doesnt really matter how it happened it has, so now i need to rebuild her. The cylinders will hone hopefully, and pistons can be re-used as are in excellent condition considering. Biggest issue is the crank shaft, the big end have corroded and such have pitted the crank, it is relatively light pitting but pitting non the less.
Being new to these engines i wasnt sure on best way forwards, buying a new oem crank will write the engine off.
So i wondered.... Can you grind these cranks? If not has anyone another solution?
Does anyone have a used crank for sale?
Or i have been offered a 2.5 crank out of an outboard but they have only 8 spline for the drive, has anyone ever swapped the end web over?

Anyone got any top tips on these engines? Anything to do/not do with them?
And regards pre-mix conversion is it something most recommend?

Thanks in advance guys

 

[Dr Honda]

Welcome... and should be a fun build. Keep the pictures coming.

 

[Rickdug]

Managed to source an 8 spline crank and after a discussion with my machinist (alan at jetshed) we are going to fit the boat drive shaft with the 8 spline rather than the crank with 14 as its one cast piece

 

[Rickdug]

 

[Rickdug]

Cylinders honed, faces of block cleaned, exhaust cleaned and put back together, and pistons in a bucket of diesel hoping i will get the rings free and useable, assume gudgeons will be shot tho

 

[Rickdug]

You will have to excuse the poor photos, phone was cover in diesel and oil... But next thing the throttle body/injectors, they are in quite a bad way and all seized up. Hopefully they should clean up, stripped down now and getting a soak hopefully will get them good again!

 

[Dr Honda]

Be SUPER CAREFUL with that throttle position sensor !!!!!!!!!!!!!!!!!!!! It's $500.

But... good job so far.

 

[Rickdug]

Thanks dr honda, i will be sure to! It isn't budging at the moment both sets of butterfly's are well siezed in!
Do you by chance know of a place for parts? Im in uk and parts are very hard to come by, used dont exist

 

[Dr Honda]

Most of what I get for the Merc engines comes from eBay, or boats.net.

Here's a link to your engine for new parts...


http://www.boats.net/parts/search/M...RIVE (PUMP)/0E379931 THRU 0E406399/parts.html


A part like the throttle body will be CRAZY expensive if you buy it new... so I would look on ebay. I'm guessing you can find one for a couple hundred USD.

Here's one for $100 that says he will ship world wide.

http://www.ebay.com/itm/Mercury-Spo...ash=item3d184797d9:g:pIMAAOSwiYFXGjxJ&vxp=mtr

 

[Dr Honda]

Oh... as far as your question on the oversized bearings... As far as I know... they don't exist. It's not normal practice to grind these cranks smaller. You either replace the crank, or you send it to a shop that can weld it up, and then grind it to normal size. FYI... a new Sportjet crank is around $1000. A re-work will be around $500. If you find a used one... make sure it's a Sportject crank. For some reason, Mercury decided to change the splines between the Jet and outboard engines.

Here's the shop that fixed up my crank...


http://www.marinecrankshaftinc.com/

 

[Rickdug]

Thanks dr honda, yes i waa hoping to have it welded and ground, but so far prives have been around £200 each journal!

 

[Dr Honda]

WOW !!!!!!!!!!!!! That's nuts !! You can buy a new crank for less. The link I sent is under $1000 USD. With the conversion... that's only 760 Sterling Pounds.


Marine Crankshaft welded 4 journals, ground/polished all, fixed the lower seal surface, and shipped it back to me for $500 USD.

 

[Rickdug]

I think 2 of them will be ok, im going to phone some of the crank welders/grinders in uk on monday see what i can get done