09-05-2007, 05:56 PM #1
Let play, what made my motor let go!
Ok this is exactly what happened.
Ski was running GOOD. Fastest it has ever ran in fact. 73 mph full tank of gas at 500ft above sea level. I had my EFI in at 6-6-1-7. All I have motor mod wise is D-plate, VF3s, and no filter box. I was also running side gapped plugs.
It started making noise but it ran ok still, tried to put it in, no go. Motor locked up. I took everything apart and this is what I see.
- Middle Cylinder Rod is Broken at the top
- Middle Cylinder is Cracked at the bottom where rod hit it
- Middle Cylinder head is smashed up
- Crank Casing is smashed at the bottom
- Piston is locked in Cylinder
- Rod bearings at the piston in Middle Cylinder are all over the place, top of piston, in crank casing... ect.
- Crank is OK
- Front and rear cylinders, piston, and bearings are OK
- VF3 Reeds are OK
- No water in hull or motor
So in my mind I see this going down. Bearings go out. Bearings lock the piston in the cylinder and then the rod breaks off. Rod then goes down cracks cylinder and casing. Motor is locked won't start because the broken rod is jammed.
This is what I want to know
What could have caused this? I don't want it to happen again since it is such a pain in the ass.... even though it gives me the need to build the motor LOL.
09-05-2007, 06:22 PM #2
Maybe the wrist pin bearing let go,causing the piston the shift all over the place.Without the bearing being 100% on the wrist pin,the slack between the wrist pin and rod journal caused the rod end to crack.The only way to confirm is to take a close look at the wrist pin.
THIS IS 1 OF SEVERAL CAUSES FOR YOUR PROBLEM.Just something to look into.
09-05-2007, 06:23 PM #3
Going to go take a hammer to the piston... Be back with info in a sec
09-05-2007, 06:29 PM #4
could it be lack of oil? engine heating the bearing up causing it to break? just a wild guess
09-05-2007, 06:30 PM #5
The wrist pin looks ok. Hole in the side of the piston though. Bearing is no where to be seen.... except in the bottom of the casing lol. The rod broke at the wrist pin though.
09-05-2007, 06:31 PM #6
09-05-2007, 06:33 PM #7
Actually the wrist pin COULD be ok.They are really strong.I have a feeling that the knocking sound you heard,could have been the play in the wrist pin,due to a bearing failure.Like i said,its 1 thing that could have caused this.You have pics?
09-05-2007, 06:35 PM #8
One word for you - DETONATION. Really, I don't know - just guessing.
09-05-2007, 06:45 PM #9
Sounds like water
Are you sure theres no water residue
09-05-2007, 06:48 PM #10
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