Seal ring on crank broken 120 hp looper

[redshad]

Im looking for any ideas to why a seal ring on my crank came apart which wiped out my block. after tear down I found the only problem was the seal ring on the crank. I rebuilt this engine 8 years ago and will try to attach a link to that thread from 8 years ago to give a little history. http://forums.iboats.com/showthread.php?t=87733
Im pursuing buying a engine block to make the repair. Any advice is welcome
Thanks for any help
Redshad

 

[Haffiman]

Re: Seal ring on crank broken 120 hp looper

Some pics might tell a bit more. Crankshaft seal rings normally does not 'break' during running. However I have noticed a couple of times that people have re-used seal-rings that blued out due to overheat/lack of oil. It then may loose its tension, start rotating with the crank and may finally break and damage the block. Another possibility is that it all started at the first start after your rebuild. If rings and crank are not richly lubricated during assembly, the ring might 'friction weld' to the crank at first start. However close inspection of crank, ring and block might tell more.

 

[redshad]

Re: Seal ring on crank broken 120 hp looper

Ok I took a few pictures. I pulled the remainder seal rings off and noticed that each one had worn down on the sides. You can see in the photos. Is this normal to wear like this? Do the seal rings remain stationary and the crank spins inside of them? Should I have replaced them during original rebuild? Also there is a photo of my crank pointing out a place where a pice of the ring made a indention. Would this be a problem? The rest of the crank looks fine.

 

[Haffiman]

Re: Seal ring on crank broken 120 hp looper

The upper ring has friction welded to the crank and rotated in the crank case. Failed recirculation from lower to upper and loss of lubrication. A few possibilities of reason:
1: Leaking upper crank shaft seal, lost suction in the upper chamber.
2: Failed resurculation from bottom to top, leaking valve/hoses.
3: Axial play in lower crank shaft bearing has left the crank 'hanging' in upper ring after installation when powerhead has been turned vertical after assembly.
I'm afraid your crank might be in critical condition. If upper ring seal does not work properly, no lubrication for upper bearing as resirculation will fail.

 

[Haffiman]

Re: Seal ring on crank broken 120 hp looper

Look at the pick for the recirculation system,and note the one-way valve in the system. If missing or defect, system will not work properly:
http://continuouswave.com/whaler/reference/graphics/OMC_V4HoseRouting.jpg

 

[redshad]

Re: Seal ring on crank broken 120 hp looper

Ok thanks for the info. I guess I will try to sell what I can and be thankfull for the eight years she ran after my rebuild. What did you see that concludes the crank to be in critical condition? Would you try to put this crank in a replacement block or not take that chance?
Thanks
Burt

 

[Haffiman]

Re: Seal ring on crank broken 120 hp looper

Depends on condition of seal ring groove and bearing surfaces. Should even be checked for straightness.

 

[redshad]

Re: Seal ring on crank broken 120 hp looper

Ok I just got to ask. Im thinking of a last ditch effort here. Has any one ever attempted to use Devcon on a repair such as mine? I have the one seal ring mating surface on the block that is wiped out. Dosent it compress the sealring to the crank shaft? I thought of trying to build that back up and machine back down and buy new sealrings and one piston. Its one of them what the heck its that or throw in the dumpster. Can anyone explain how the seal ring works? Does the crank spin inside of the seal ring and the ring stays put due to being compressed by the block?