Yamaha Ox66 using way to much oil!

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scjmc

Petty Officer 2nd Class
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My 1999 Yamaha ox66 250 is using oil at about a 25 to 1 ratio. I do know what is causing this. I have adjusted the oil link rod to specification, and it moves freely. I have checked the bilge and cowling for leaking oil and I have found none. Does anybody have any ideas? I guess it could be worse and be the opposite!
 
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scjmc

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Re: Yamaha Ox66 using way to much oil!

Bump. Anyone?
 
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PBJohn

Seaman
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Nov 26, 2008
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Re: Yamaha Ox66 using way to much oil!

They engines smoke as is so at 25:1 you would smoke out the whole marina. You can do a volume check as described in the manual. Are you sure the oil tank wasn't filled when you fueled and now looks like double oil consumption?
 
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scjmc

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Re: Yamaha Ox66 using way to much oil!

It smokes quite a bit. I have been tracking oil usage for about the last 50 hours and it seems to hover around 30:1. I have to run the engine hard with the setup I have 4600-4800 RPM cruise, so close to 50:1 would make sense. Even with the WOT ratio of 50:1 I am using about twice as much as I should.
 
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scjmc

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Re: Yamaha Ox66 using way to much oil!

Yes the draw tube is clear. I just installed a new o2 sensor about 4 hours ago. That fixed a miriad of other problems that I had.... Thanks for the link to that post. Cousinabe did you ever get your blown motor fixed?
 
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rodbolt

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Re: Yamaha Ox66 using way to much oil!

how did you adjust the oil link arm?
have you checked the oil pump shaft seals?
usually with the 3.1L motors its an incorrectly adjusted link arm.
 
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scjmc

Petty Officer 2nd Class
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Re: Yamaha Ox66 using way to much oil!

I adjusted the oil link rod when I did the link/sync. I used a feeler gauge and put it to spec-I think it took 1 turn to put in spec. That didnt seem to make a diferance though. How do I check the oil pump shaft seals? Take the pump off and see if it is leaking into the block? Thanks.
 
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rodbolt

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Re: Yamaha Ox66 using way to much oil!

only way to test the shaft seals is to pull the pump. all the seals and orings are replacable on the pump shaft.
the only way to properly set the oil link is for the bottom two shutters being dissconected from the throttle link insuring the shutter is FULLY closed and not at idle position.
most the time I have to cut a few threads off the arm to get it in spec.
 
cousinabe

cousinabe

Senior Chief Petty Officer
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Nov 13, 2001
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Re: Yamaha Ox66 using way to much oil!

scjmc said:
Yes the draw tube is clear. I just installed a new o2 sensor about 4 hours ago. That fixed a miriad of other problems that I had.... Thanks for the link to that post. Cousinabe did you ever get your blown motor fixed?
Click to expand...

yes, got the motor fixed. two problems caused the meltdown, bad wiring harness(stopped the transfer) and bad switch on engine oil tank(failed to go in red zone caused by swelled up rubber internal piece; preventing safe mode). I'm guessing the engine switch wasn't working for a while and then when the harness failed - kaboom.

FYI, I had to cut five threads off my oil linkage rod to adjust.
 
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rodbolt

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Re: Yamaha Ox66 using way to much oil!

yep, and I bet now cousinabe will test his oil alarms and transfer on the 100 hour or yearly intravel,just like the maint manual says.
that rubber 4 leaf clover looking thing is peculiar to the 3.1L motors and will curl and prohibit the float switch to close if the oil level hits the low zone and the engine will purr until it quits.
there is a periodic maint action for the engine oil tank filter and switches.
 
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