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My 2006 F115 (450 run hours) is losing oil. Enough that after about 30 hours the low oil pressure warning will show and the oil level is low. Did a leakdown test and no more than 4% loss on any cylinder. Ran seafoam and ringfree thru at shock levels but that did not appreciably help compression (~ 218 on all cylinder +- 2 psi) or leakdown results. Yamaha dealer here with a 5 star mechanic changed the oil and marked the dipstick to get a baseline. He hooked it to yds and the results are attached. Roughly 12 hours of runtime later, oil level fell 1/2 inch on stick so I brought it back. There is sits (backlogged). It does not produce smoke and the plugs do not looked fouled in anyway. No visible oil leaks while in the driveway or in the water. I had changed the water pump myself previously as a maintenence issue and was wondering if I had nicked a seal. Any ideas?
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Have you used another oil brand recently ?
If this is the case, then you might have hardened and thus leaking valve stem oil seals... Not sure about the specific motor, but in other engines it is not very difficult to change them, without removing the heads ...
Just my two pence...
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most likly from the oil pump,run it 10-25 minutes then drop the lower unit and see if the shaft is oily.Comment
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Same oil has been used for the most part. If the valve stems were leaking more than likely I see discolored plugs or smoke, correct?
I am assuming the oil pump and its seals as well. It's is in the shop now and I assume that's what they will do. Is that a fairly common occurrence or not? I'll report back.Comment
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UPDATE: Mechanic finally called me back. All cylinders had good compression and at TDC has nearly 0% leakdown. Using a breakerbar to hold the flywheel, he did the leakdown test as the pistons traveled down the cylinders. #1 had 30% at a certain point as did #4. He scoped the cylinders and found some markings. He believes that is where the oil is going. He said that at high rpm no smoke would be noticed. I asked about dropping the lower unit and checking for oil. He said more would be evident if that were where the oil were leaking from. He also said he could see where the splines met the crankshaft and no excessive amount of oil appeared to be present. He'll be contacting Yamaha today with his results to see what they recommend. Does all this seem plausible? If so, would the course of action for warranty repair be a new powerhead or a rebuild (which I am not too thrilled about)?Comment
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I brought my '06 115 to a shop for water pump. he found a bad oil pump. I wouldn't have seen this myself. He said it has been an issue with this motor??? Warranty covered it. Just in time...Comment
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before ya gets all yiggy yiggy have them run a YIES engine treatment and then retest.
it works better than combustion chamber cleaner but is not avalible for resale to the public.Comment
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update and resolution
The mechanic performed a leak down test and, at tdc, all was geat. He then used a breaker bar to move the cylinders down and at a certain point he found 30% leakdown on #3 and #4. I did the leakdown at tdc but did not use the breaker bar and cylinder movement. I have to learn to do that. Anyway, he then scoped those cylinders and found what appeared to be scaring from water along the lower portion of those cylinders. He removed the head gasket which seemed fine to him and confirmed the cylinder damage. A call to Yamaha and they honored the warranty and replaced the cylinder head assembly, cylinder block assembly, oil pump, and oil strainer. $5100 worth of work. Mechanic never could figure out how the water got into those 2 cylinders. Maybe a bad casting.Comment
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