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Yamaha 99 4 stroke smoking bad

S

svdances

New member
Last season my motor filled th

Last season my motor filled the crank case with gas.
This season I replaced the fuel pump membrane and put fresh oil in it. Its started to smoke really bad and went through a quart of oil in about ten miles. then water in the oil. The motor other then smoking and dumping oil ran great.
I pulled the head and replaced the head gasket.
after that it is doing the same with the smoke and allot of oil on the water.
I've only ran it enough this time to know it has the same problem. Is there something I'm overlooking?
 
"I'm not understanding how

"I'm not understanding how over propping or valves have to do with the over oil out put in the water as one quart per ten mile and or the water in the oil!
A head gasket or something else as water warmed fuel per economy as the lope near the fuel pump,but I'm still baffled by the oil loss! I've had this motor over a year without a problem."
 
"Doug, if the thermostat is st

"Doug, if the thermostat is stuck open the engine will not come up to normal operating temp and unburned fuel will slowly fill the crankcase...the oil/gas mixture will spill out the overfill into the water check the thermostat housing for proper temp as well as the tell tale water exiting the engine...it should be warm as well. good luck"
 
Hey Rollie
Yes the motor fill

Hey Rollie
Yes the motor filled with fuel last year.
I'm starting to think this hurt the gaskets
on the oil pan and is allowing water from the pick up tube and oil to escape.
I don't understand the excessive blow by.
The prop never had a problem in the past 2 years
of running. I don't think the thermostat has any thing to do with blow-by.
I go back to the fuel in the oil and work up from there. It deffantly created
blow by
excessive oil consumption
water in the oil
lots of blue smoke.
 
"Doug, the engine will burn oi

"Doug, the engine will burn oil if the crankcase is excessively overfilled. It doesn't take much to do this as the proper amount is only a quart/litre.
When the crankcase is flooded like this the rings can't function properly as to much dilluted oil is being thrown up onto the cylinder walls. ... also if the engine willrun a little rough with changes in speed. If there is water in the oil it will be creamy and whiteish (white is the key for water) fuel/oil will be brown with the oil being very thin. If it is white, look for a problem with corrosion with the oil pan, allowing water in there."
 
Rollie
I put the motor back t

Rollie
I put the motor back together after going through as much as posible.
It still smokes not as bad and it still is spitting oil. I only ran it on the stand for a half hour with water fed. It runs great even at a low Idle.
I think I'll bench it till next season and do a ring job and a full gasket set. My feeling is I have a bad gasket on the lower end (power plant to the pan) I just pick up a Suzuki 15 4 stroke so I can live without this one till then.
I'm in Guatemala and you can't get 9.9 parts and the shipping will eat you up.
Thanks again for your sugjestions!
On the flip where would you pick up a kit or do you have to buy everything indidually.
Doug
 
"Doug, I'm sure you can bu

"Doug, I'm sure you can buy a complete engine gasket set. The rings would be a seperate order. I'm presuming that the oil is creamy white so you are sure it is water filling the crankcase. I would find the source of the water first, fix that and see if it runs smoke free. You likely will find that if the oil level stays where it should that the smoking will stop. Savings you the time and cost of re-ringing. If it still smokes then first determin why....rings or valves....otherwise your chasing a ghost and spending money along the way. Rollie"
 
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