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Gas in the engine oil ??? a lot!


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buckhunter
User

Mar 15, 2009, 3:18 AM

Post #1 of 4 (2602 views)
Gas in the engine oil ??? a lot! Sign In

83 lincoln mark 6, 5.0 engine, I keep this car in the garage, do not drive it much, a Sunday or show car, well I want out and for no real reason I checked the oil, boy am I glade I did, it was about 1 1/2 " over full, and smell of gas, I go under and drain it, it was so weak as if no oil at all, I have not put in oil or new filter as I want to fix it before I do that, trouble is I do not know what to fix, ??? it has a throttle body with two injectors mounted on top, I turn key on and off, look in with a light and do not see them leaking, and the fuel pump is in the tank so I do not have one in the block that could have rupture`ed, so I have no idea, If you can help Thanks so much, if not Thanks anyway for your time. Bill


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 15, 2009, 3:28 AM

Post #2 of 4 (2601 views)
Re: Gas in the engine oil ??? a lot! Sign In

How long has it been stored for this to happen since known ok?

Injectors kinda must be leaking down. I suppose that even without fuel pump pressure that plain expansion with daily heat changes where stored MIGHT be able to pressure the fuel tank just a tad and push fuel thru - a maybe.

Even 1983 used evap emmsion systems. You may have a plugged up canister or hoses to it. This may just self correct with a good run if running well with new oil and filter.

DON'T run on thinned oil as I'm sure you know - it's not capable of correct lubrication or worse - washes off any existing lubrication for the engine.

Idea: Perhaps store the car with slightly loosend gas cap if safe where it's stored. Put a reminder in your face on the steering wheel that it's left that way! All things perfect you shouldn't need to do that but dunno how long it sits and the overall conditions,

T



buckhunter
User

Mar 15, 2009, 3:40 AM

Post #3 of 4 (2599 views)
Re: Gas in the engine oil ??? a lot! Sign In

Hi Mr G, when I was checking to see if the injecters was leaking after shut down, not running as I have not replaced the oil and new filter yet, but I turned the key on then off, looked in the throttle body to check the injectors for drip, seen none " BUT " did see a bit of fuel on top of the throttle body around the fuel pressure reglator, I will say wet to the touch, not a lot but wet, ??


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 15, 2009, 5:33 AM

Post #4 of 4 (2595 views)
Re: Gas in the engine oil ??? a lot! Sign In

? The only way fuel could really get into the oil is thru that throttle body so there's an issue there. We are talking about an old car now with VERY limited use with long periods of storage but not completely "moth balled" as in drain it out for a 20 year sleep or something.

The the fuel from just the pump doesn't account for the volume you found so I'm blaming the pressure on expansion of fuel and air over it in the gas tank pushing by itself.

The gas tank vents to a canister that I think is nicely hidden under side and back of the RF headlights. That thingy takes the fumes (hopefully only fumes) from the gas tank and when engine is started returns the fumes then caught up in charcoal to the intake - somewhere at a metered rate so as not to cause it to run lousy so my guess is to the area near where this TBI injection is. You might not see that fuel at all and would have to inspect hoses to that canister for issues, blockages or something IF that was the source at all.

Just a maybe that injectors can get some pressure as well - so slow that it's just a couple drops under low pressure and if the car was a daily driver you might never notice anything. They really shouldn't allow anything past them but it's possible.

More: The air on top of fuel in tank is DENSE with fuel vapor. Enough to condense to a liquid again probably with temp changes. It amazes me just observing a 6.5 gal plastic gas can I have (not vented) how much it expands and contracts with temps. Goes from a scary bulge to sucked in! My own storage temps for a car right now are a limited range of 40F to short times of 85F give or take. That's still some considerable temp variation but hasn't been an issue with many cars I've stored over the years. Your temp changes might exceed what I observe just exacerbating the pressure and vacuum of expansion and contraction.

Thoughts: The gas cap itself has a lot of features for the pressure and vacuum control of the system. You understand as you drive and use fuel that the tank would squish from a vacuum if the cap was sealed too tight or if (dunno) intended to seal tight then the venting comes from all the way back up front at that canister which is a squarish/rectangular shaped thing. Never had a problem with one so zero for much more on the item from me.

So - IMO it's one or the other causing this: Injectors can leak with low pressure or evap system is allowing liquid up to the intake. I can't think of any other way short of vandalism that gas would get into the oil!

About 10 years before this car gas caps were vented right at the cap which is why I suggested for this exact situation a possible solution would be to "de-pressure" the tank by leaving cap loose.

It's also totally possible that after a good run this car won't do this again - I can only guess the conditions it's under even while stored,

T







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