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Cracked Crankcase

Aaron Tonks

Active Member
Messages
5
Reaction score
1
Points
40
Boat Make
Yamaha
Year
2006
Boat Model
SX
Boat Length
24
Over the weekend I noticed water leaking out the side of my engine. After a closer look I can see that it is a crack in the Crank Case. Has anybody ran into this problem, and have they been able to repair it without replacing the engine?
2005 SX230 HO.
 

Attachments

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Any water in the oil ? I do remember reading something on the other jetboaters site that they removed the motor and welded . Hopefully it works out how many hours ?
 
I removed the engine, ground out some of the crack to increase bonding surface area and applied JB Weld as a doubler. I have not experienced any leaks, no evidence of further crack propagation and no water in oil since the repair. I know you got a decent picture; but a “perfect shot” with great focus on the crack would be helpful in comparing with mine.
The crack:
36513D6B-971C-4AF3-9553-4DF7DCB12FAB.jpeg
Ground out/down:
B7A63553-19EB-4383-8302-E3BF5D4C2A71.jpeg
The repair:
E731C322-3312-4EEF-A53B-B949CC351320.jpeg
 
I had this issue, too. i pulled the entire engine while doing a hull repair and took it to a local welder that I trusted. he was able to fix it without any disassembly.
 
Note @CrankyGypsy said it was a welder he trusted. I think he had some mad skills on aluminum as it can be very tricky to weld something like that, especially with internal passages. Many suggest preheating of the block to reduce localized stressing during the weld; but that requires disassembly. I am pretty sure he must have pulled the exhaust though. Getting in there with any tool is a &/+([HASH=279]#![/HASH]
 
JB weld is not a long term solution.
 
yes, the exhaust was off - I also removed the sensors and hoses on that side, along with the starter. if I had been told it would've required a complete disassembly of the block, I would've found an alternative like @Seadeals and rode it out with my fingers crossed. I owned the boat almost three more years without an issue with that weld job.

you can see the two cracks on either side of the thermosensor.
exhaust port.jpg

@Aaron Tonks , yours looks as bad as mine did, (edit) def worse than Seadeals'.
 
Last edited:
Welding on an aluminum block which is like a giant heat sink and not ending up with a cold weld takes mad skills. MIG hot enough to get a good weld would be on the ragged edge of burning through and TIG with the heat being sucked away requires good eyes and fast/steady hands. Complete disassembly, preheat of the block, and an Aluminum TIG guy with mad skills is the only way to go for a lasting repair IMO.
 
I removed the engine, ground out some of the crack to increase bonding surface area and applied JB Weld as a doubler. I have not experienced any leaks, no evidence of further crack propagation and no water in oil since the repair. I know you got a decent picture; but a “perfect shot” with great focus on the crack would be helpful in comparing with mine.
The crack:
View attachment 91483
Ground out/down:
View attachment 91484
The repair:
View attachment 91485
Which engine was the crack on? Mine is on the port side, hopefully with removing a few parts I will be able to get to it without removing the engine.
 
@Aaron Tonks Mine was starboard, so pulling it was a must. Based on the size, (and whatever you intend to attempt) I really think you will want to pull it no matter what. Having it on the bench was a huge help and the quality of anything you attempt will be WAY higher than “standing on your head”. @itsdgm came up with a really nice removal/install instruction checklist. After a (overkill) hoist install in the garage, it only took a couple hours.
DC5467D0-7A22-4A4F-80EE-A6FD7B489456.jpeg
17922126-7058-4526-BB97-6BE5EF1B5929.jpeg
C5A4676C-2404-4308-8855-EA732D305A9D.jpeg

@Noko I understand the initial feelings on what many may consider a worthless band-aid; but the key is for each owner to define “long term” assessing how many years they wish to operate the boat how many hours per year and stomach what probability and magnitude of failure could be based on their own WAG of repair limitations and extent of cracking.

I caught it very early, focused on a creating a precision multi-layered repair on the workbench (not just mixing up some goo and smearing it all over). My decision has already paid for itself multiple times over with multiple saved vacations and lots of weekends on the lake. My “long term plan” is buying a VX waverunner if it fails and swapping engines so I can play with a short block rebuild.
 
Since you are dealing with it, thats different. And you will find out the results. I've had bad results with JB Weld
 
Note @CrankyGypsy said it was a welder he trusted. I think he had some mad skills on aluminum as it can be very tricky to weld something like that, especially with internal passages. Many suggest preheating of the block to reduce localized stressing during the weld; but that requires disassembly. I am pretty sure he must have pulled the exhaust though. Getting in there with any tool is a &/+([HASH=279]#![/HASH]

Maybe too much info...but here is an article on HAZ.
 
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