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Gas in oil
Topic Started: Aug 12 2012, 01:57 AM (1,302 Views)
Shinrin
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Can anyone give me a list of places to check as to why there is gas in my oil 500 miles after an oil change?
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crankcase


Just a guess, but maybe leaky injector?
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Shinrin
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I've been thinking leaky injector for awhile now. Warmed up it bogs down a bit like it's flooding. Doesn't stall, but definitely bogs down.

Would a leaking injector be able to get that much gas in the oil without stalling the car? Oil looked like black water when I drained it out today.
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Old Man


next time the engine is cold turn the key only to the on position and see if the injecter is seeping----after it warms up turn it off and see if it keeps seeping til the line pressure goes away.

Dont know for sure if this would tell you anything but it seems to me that it should
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Shinrin
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So no others ideas? Cracked head or block?
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Old Man


cant think of any other circumstance where a supply of gasoline is adjacent to an oil passage.

do you have an ex wife or other enemy that could be adding gasoline to your oil??
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charlesufarley
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Grease monkey
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Leaking injector is the most likely place for fuel to get into the oil. If it is not dripping after you shut it off, possibly a faulty or unplugged coolant temp sensor would cause the computer to think it is colder than it really is. This would cause an unusually rich mixture which would explain fuel in the oil. Does it puff black smoke when you rev it up?
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Shinrin
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No on the enemies.

It does blow black smoke occasionally. So most likely, it's my injector leaking or the car running too rich then.
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charlesufarley
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Grease monkey
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That's my best educated guess from here. You can check the resistance of the coolant temp sensor with an ohmmeter. If it reads infinite, the sensor is toast. Usually higher resistance indicates lower temp and vice versa. If sensor is open (not able to allow electricity to flow through it) the computer thinks the coolant temp is -40F (which is the lowest it will read) and will add a bunch of fuel. Oh, almost forgot, intake air temp sensor will cause similar symptoms to a lesser extent. If coolant sensor checks out OK, try air temp sensor. Don't dismiss the possibility of an intermittent condition, such as a wire rubbed through and grounding on the engine, as that isn't outside the realm of possibility either. Hope this is helpful.
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Khaney01
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Hillbilly at large

The only place that the gas could get in is through the injector. The "why" could be a couple things. Leaky injector letting fuel pressure bleed through after the engine is shut off, or, a rich condition caused by a sensor malfunction. You'd see a LOT of black smoke if it was running rich all the time. A big puff of smoke as the engine cleared thecylinders at startup if it is a leaky injector
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Shinrin
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At heavy rpms I sometimes get a puff of black smoke. The engine hesitates at certain points, and when I give it throttle it'll sort of struggle, then cough up a cloud of smoke, and the engine drives a ton smoother afterwards.

So, extra fuel is getting into the intake, for whatever reason. The extra fuel is dumped into the cylinders and isn't combusted, how does this get into the oil? Leaking past the rings?

Also thank you everyone for your advice.
Edited by Shinrin, Aug 14 2012, 06:19 PM.
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Khaney01
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Hillbilly at large

You need to check the sensor functions. CharlesFarley gave you a great place to start. If it is happening while running the injector is the least of the problem.
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Shinrin
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I will, I'm just trying to understand the specifics of the gas actually getting into the oil.

I've had a code for air temp sensor before, but it went out and never came back. So I'm leaning towards the wiring being damaged as opposed to the sensor itself. I'll test them on my lunch break in a few days.
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charlesufarley
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Grease monkey
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Yes, the extra fuel will leak past the rings. Also it will damage the rings if the condition is not corrected. Fuel washes the thin film of oil off the cylinder walls that allows the piston and rings to slide with very little friction. No oil= mucho friction.
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poorman1


leaking fuel pressure regulator diaphragm??
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