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F300 timing belt failed. Thrust bearing? What should I do first?

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  • TownsendsFJR1300
    No answer about where your oil went...But, I would check the filter as you posted. Drain the crankcase as well and check for shavings..

    If not loaded with metal debris, I'd put a new belt back on, and do a leak down test.

    That will tell you if the valves got bent or any internal damage causing low compression / leak down. Even if it's a non-inference engine, running with no/low oil will cause excessive wear..

    If that passes and it does crank up, I'd definitly check for oil pressure or lack of.. That oil loss (guessing), may have been blown out(perhaps out the lower seal as nothing was obvious).

    When was the last time you checked the oil? Did you see any signs of oil on the exterior of the engine after you pulled the boat from the water?

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  • walleye1
    Call yamaha customer service with your primary id number and ask them.

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  • F300 timing belt failed. Thrust bearing? What should I do first?

    I'm working on a F300 with a manufacture date of 03/2013 and only 254 hours (I thought the thrust bearing "issue" was fixed after 01/2013?). Was having a good time w the kids, and suddenly the oil pressure dropped and the engine stalled. Repeated attempts but could not restart. I checked the oil and it was EMPTY. We got towed back to the dock. I filled it up with oil and tried to crank and no go. Then I noticed the timing belt was all chewed up and off the pulleys.

    So, do I have the dreaded thrust bearing failure? Is this an interference or non-interference engine? I have been doing research but cannot find a clear answer. I believe the 225/250 is non interference and below is interference. But I have seen no reference to the F300 (hopefully the bigger engines are all non-interference?). If it is interference, and I continued to crank it, did it bend the valves & damage the pistons, or is that just already guaranteed once the belt failed?

    I tried to pry up on the flywheel, and absolutely zero movement, so I am stumped. Could i just have a bad belt? Why did the oil disappear? I fear the engine is "TOAST", so I am going to attempt a little investigation myself before I hire a pro. I figure I will cut the oil filter open and inspect for signs of heavy metal damage. If I find this, then I guess there is no point in continuing.

    What would you do first? I believe it is not as simple as putting a new belt on, there is a specific method and if not followed I could damage the engine if it is already not toast. I have a new filter and oil and ordering a new belt at any moment if its worth trying? Since the warranty expired, I have been using Sierra maintenance items and fluids which I don't believe should be a problem.

    Please advise. thank you.
    Last edited by Chsboats; 10-07-2019, 09:39 AM.