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I have an f115 that seems to be burning oil. Under a heavy load I can see smoke off in the distance behind me while running. Also while running in yard there is a black spot on groung after running it and a thin black film on top water on my driveway while running. I do have to add oil regulary.I read in another post that prop size could affect this and I'm wondering how. I do think I need to go down a pitch as I only turn up about 5700 rpms. Any ideas or what else can be causing this. I also have a rough idle to and stalls eventually, down to about 600rpm but runs fine at any other rpm. Could this have anything to do with it? Thanks
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you may have a stuck open t-stat. this will keep the engine from reaching proper operating temp. you may also want to do a leak down test. I would get the engine checked out anytime you notice something not right, these motors can get real costly if you keep using it with something wrong. 5700 RPMs sounds about right. -
I am not a mechanic but I recently had a powerhead replaced via warranty for a loss of oil issue on a 2006 F115 with 430 hours. 2 cylinders had water damage (though no fault of mine) and were scarred losing oil although I never saw smoke or a film. What about compression check? Have you pulled the plugs and inspected them. May have bad or misaligned rings on a cylinder or 2. A leak down test should also help diagnosis the issue. In my case I did a leakdown test and all appeared well. I did it at tdc only and the scarring was not evident at that point. The yamaha tech did it all the way through the pistons' travel and that is how they found the leak. As I understand it, that can be a dangerous test to run because the flywheel wants to turn past tdc. He had some mech's help him by holding the flywheel in place and gradually advanced it. Not sure how a diy'er would do that. If anyone has any advice I would love to hear it.
May also be bad valve seal on an exhaust valve. I believe a leakdown test my help find that as well.
Just my 2 cents and again I am not a mechanic. I may be way off base.Comment
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theromastat
I already replaced the thermostat, did nothing. Done a leakdown test but used a Harbor Freight tester, another words came out different everytime I tried it. My top plug seems to have a lot of black build up compared to the other three. I assume this is the problem cylinder.Comment
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go ahead and pay a professional yamaha certified mechanic to do a leak down test. get a master tech if you can find one near you, yammy site has a list of them..be a good $100 to spend right here.Comment
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