Bad fuel 10% ethanol?
05-25-2006, 11:15 AM
#21
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Re: Bad fuel 10% ethanol?
Just a stupid thought but did you prime the oil pump prior to starting the engine for the first time? I just did mine , wanted to make sure I had oil coming out of every pushrod! Like you said , pulling the engine is a pain in the azz and lose too much time on the water.
Last edited by hunster; 05-25-2006 at 11:18 AM.
05-25-2006, 10:14 PM
#22
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Re: Bad fuel 10% ethanol?
Yes I did prime the oil pump. But I found out one better. My machine shop has a machine that will spin the engine fully or partially assembled at 500 RPM's. You can check compression and oil pressure.
I pumped out 10 gallons of the old gas today and mixed it with 10 gallons of 93, ran it in my truck and everything seems to be OK. I am going to do this in the car and repeat next week. I will let you guys know how it turns out. It seems to be a better idea than finding a place to dispose of it.
I pumped out 10 gallons of the old gas today and mixed it with 10 gallons of 93, ran it in my truck and everything seems to be OK. I am going to do this in the car and repeat next week. I will let you guys know how it turns out. It seems to be a better idea than finding a place to dispose of it.
05-25-2006, 10:36 PM
#23
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Re: Bad fuel 10% ethanol?
It is quite possible that bad fuel did in your bearings. You likely had low level detonation in the engine. If the cylinder temps are kept low enough the detonation will kill brgs before it burns the pistons. Basically the detonation causes excessive downward force on the pistons due to colliding flame fronts on top. This squeezes the oil out from between the top bearing cap and the crankshaft. Since the bearing is softer and sacrificial it wears away and you end up with wear on the top shell but not the bottom. This is more likely to happen on engines that run cooler (boats) and richer (boats) since the lean burn you find in cars now will damage or destroy the piston before the bearing will wear. I have seen it a few times where both things occured-the piston was badly pitted/melted and the bearing was excessively worn on the top shell. Everybody is always so focused on the pistons they miss the bearings half the time. If you are getting rid of the gas anyway you should be in good shape as long as your A/F ratios and timing advance are good.
05-26-2006, 07:10 AM
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Re: Bad fuel 10% ethanol?
Originally Posted by insptech
It is quite possible that bad fuel did in your bearings. You likely had low level detonation in the engine. If the cylinder temps are kept low enough the detonation will kill brgs before it burns the pistons. Basically the detonation causes excessive downward force on the pistons due to colliding flame fronts on top. This squeezes the oil out from between the top bearing cap and the crankshaft. Since the bearing is softer and sacrificial it wears away and you end up with wear on the top shell but not the bottom. This is more likely to happen on engines that run cooler (boats) and richer (boats) since the lean burn you find in cars now will damage or destroy the piston before the bearing will wear. I have seen it a few times where both things occured-the piston was badly pitted/melted and the bearing was excessively worn on the top shell. Everybody is always so focused on the pistons they miss the bearings half the time. If you are getting rid of the gas anyway you should be in good shape as long as your A/F ratios and timing advance are good.
05-27-2006, 11:18 AM
#25
Re: Bad fuel 10% ethanol?
Originally Posted by insptech
It is quite possible that bad fuel did in your bearings. You likely had low level detonation in the engine. If the cylinder temps are kept low enough the detonation will kill brgs before it burns the pistons. Basically the detonation causes excessive downward force on the pistons due to colliding flame fronts on top. This squeezes the oil out from between the top bearing cap and the crankshaft. Since the bearing is softer and sacrificial it wears away and you end up with wear on the top shell but not the bottom. This is more likely to happen on engines that run cooler (boats) and richer (boats) since the lean burn you find in cars now will damage or destroy the piston before the bearing will wear. I have seen it a few times where both things occured-the piston was badly pitted/melted and the bearing was excessively worn on the top shell. Everybody is always so focused on the pistons they miss the bearings half the time. If you are getting rid of the gas anyway you should be in good shape as long as your A/F ratios and timing advance are good.
05-30-2006, 11:00 AM
#26
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Re: Bad fuel 10% ethanol?
Great info! This is what I was told may have happened. My machine shop is covering most of the damage under warranty but I don't want it to happen again. I will definitely be more careful about the fuel. I run my timing at 34 deg so I should not have any problem there. Using an O2 sensor the boat runs best in open loop at .75 to .8 volts(slightly rich). Does anyone else agree with this analogy.
Thanks,
Jeff
Thanks,
Jeff
