Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Welcome to Jetboaters.net!
We are delighted you have found your way to the best Jet Boaters Forum on the internet! Please consider Signing Up so that you can enjoy all the features and offers on the forum. We have members with boats from all the major manufacturers including Yamaha, Seadoo, Scarab and Chaparral. We don't email you SPAM, and the site is totally non-commercial. So what's to lose? IT IS FREE!
Membership allows you to ask questions (no matter how mundane), meet up with other jet boaters, see full images (not just thumbnails), browse the member map and qualifies you for members only discounts offered by vendors who run specials for our members only! (It also gets rid of this banner!)
My new motor is due for delivery Monday so I completely pulled old engine apart. I do believe the problem was the timing chain guide. The part of the guide that broke is where the tensioner actually pushes on the guide. I think it was just a faulty part. The pieces of the guide blocked the oil passage just enough to starve the last valve which ended up sticking. Piston hits valve, piston explodes etc.
@Jaycav Thanks for the continuous updates. I have some questions. I cannot see the smashed piston and broken lifter scenario without a broken timing chain. Is it possible that a plastic guide piece or whatever caused the guide to shred got between the cam and the lifter? Did the guide piece delaminate? What does the timing chain tensioner look like? Therefore, I do not see how you are responsible for this. Am I reasoning correctly?
Edit Second scenario: Delaminated chain guide allowed for loose chain leading to chain jump.
@Jaycav Thanks for the continuous updates. I have some questions. I cannot see the smashed piston and broken lifter scenario without a broken timing chain. Is it possible that a plastic guide piece or whatever caused the guide to shred got between the cam and the lifter? Did the guide piece delaminate? What does the timing chain tensioner look like? Therefore, I do not see how you are responsible for this. Am I reasoning correctly?
Edit Second scenario: Delaminated chain guide allowed for loose chain leading to chain jump.
The timing chain was not broke. The tensioner looked fine and was still Functionable. The guide did look like it delaminated. The chain seemed tight but your theory of chain jump which would cause a valve to hit a piston is a possibility and it makes sense to me.
The timing chain was not broke. The tensioner looked fine and was still Functionable. The guide did look like it delaminated. The chain seemed tight but your theory of chain jump which would cause a valve to hit a piston is a possibility and it makes sense to me.
When I say delaminated I mean-the new guide looks like it has a thick curved wedge fused/plastic welded to it. That is the part that is missing from the failed guide. The chain tensioner pushes against that wedge. That should not have fallen apart. The slack created when that wedge came off the guide, could have allowed the chain to jump.
When I say delaminated I mean-the new guide looks like it has a thick curved wedge fused/plastic welded to it. That is the part that is missing from the failed guide. The chain tensioner pushes against that wedge. That should not have fallen apart. The slack created when that wedge came off the guide, could have allowed the chain to jump.