Classic Mustangs (Tech) Technical discussions about the Mustangs of yester-year.

Oil smells of gas

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Old Oct 27, 2009 | 09:00 PM
  #1  
jduvall88's Avatar
jduvall88
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Default Oil smells of gas

The car is running rich so I assume that is at least part of the problem.

What else do I need to check to determine why my oil smells (not over powering but unmistakable) of gas. I was having some issues with the starting of the car not to long ago (the whole starter system basically went belly up) so I may have flooded it a time or two trying to get it started. I don't remember in the past it smelling of oil (or even checking but I'm sure I did)

Should I just start with an oil change and see if it still smells? If so where should I start looking? I'm going to try messing with the carb this weekend, I think I understood what I read (turn both the screw in front and in back all the way in and back them out a half turn each till what?)

Sorry for all the questions lately, I'm in way over my head and I love it
Old Oct 27, 2009 | 11:50 PM
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Change the oil and then see if the new oil smells like gas after running? That is what I would do. Im not sure if that is the right thing to do.
If it does then the gas has to be leaking in somewhere which would probably be a gasket. I am not sure if it can leak in through a defective mechanical pump or maybe it is a deformed cylinder or piston that is causing a leak? Just trying to give you ideas. I am interesting in what the result is so I will keep on the topic as more replies come in
Old Oct 28, 2009 | 12:14 AM
  #3  
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Yes, change your oil and do it ASAP. In fact, I wouldn't even run it anymore until you do. If there is gas in it, your oil is severely degraded and can lead to engine failure. As for how it got in there, you said it's running rich. That would be the first place I would concentrate on. If the carb is flooding from something like an incorrect float setting or a stuck float needle, it will start dumping raw fuel in the cylinders which will wash past the rings and end up in the oil. I have seen mechanical fuel pumps with a bad diaphragm leak fuel into the oil system but it's not as common as the carb problems.

Last edited by hiboostwoody; Oct 28, 2009 at 12:16 AM. Reason: spelling - damn sticking keys
Old Oct 28, 2009 | 01:16 AM
  #4  
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JMD
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Oil in the gas can come majorly from two sources in your Mustang, one is a broken fuel pump dropping raw fuel into the crankcase, the second is past the rings, i.e flooding and/or a rich mixture.

Prpbably the best course of action will be to change the oil, fix the rich condition, and monitor the situation.
Old Oct 28, 2009 | 05:17 AM
  #5  
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Haha wow I am surprised at how close I was. Look at all the information I have picked up on this forum Sweeeeet.
Old Oct 28, 2009 | 07:49 AM
  #6  
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Originally Posted by JMD
a broken fuel pump dropping raw fuel into the crankcase
Same thing happened to me on my 60 F250 w/351C .... it was a fairly new fuel pump too ...


If you have a mechanical fuel pump: Unless you know of some reason why your carb would all of a sudden have stuck floats, I'd change the fuel pump first, then change the oil.


As someone else mentioned .... it is VERY BAD to even start the engine once if your oil pan is full of gas (main bearings and pistons lubricated with gas)
Old Oct 28, 2009 | 08:25 AM
  #7  
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urban_cowboy
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When engines run rich, the fuel will actually wash down the cylinder walls removing the oil and run past the rings. This is bad for two reasons. One, you are diluting the lubrication of the engine with a flammable and explosive substance which is dangerous. Two, you are removing the lubrication from the cylinder walls which will lead to premature cylinder and ring wear. Not to mention you are running more fuel than you need through the gas tank, the engine is not as efficient, and your power will be down from its potential.

I would suggest you first have the carb and ignition tuned. I would then replace the plugs and change the oil and filter. If you still are getting gas in the oil, you may have an intake gasket leak, excessive blow by, or some other more serious problem.
Old Oct 28, 2009 | 10:50 AM
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Good suggestions above.
I would change the oil first with cheep oil, then fix the problem. Then change it again with good oil.
It would be worth the extra $10 to reduce a chance of an engine fire or explosion,
plus the oil dilution issue, while you're working on it.
Old Oct 28, 2009 | 03:58 PM
  #9  
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jduvall88
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Originally Posted by 1971mach1
Good suggestions above.
I would change the oil first with cheep oil, then fix the problem. Then change it again with good oil.
It would be worth the extra $10 to reduce a chance of an engine fire or explosion,
plus the oil dilution issue, while you're working on it.
Guess saturday Ill go to autozone and buy what ever the cheap stuff is, and then maybe royal purple (a buddy of mine with an old vette swears by the stuff)

Are vacuum gauges expensive or hard to use?
Old Oct 31, 2009 | 03:00 PM
  #10  
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jduvall88
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Where can I find the proper vacuum spec? Its a 289 with a holly 600cfm (1850-3)?

I just bought a vacuum gauge and I'm not 100% what I'm doin but I'll figure it out via the internet

Edit: Had to take the gauge back it wasn't able to connect right. So I just kind of did it by nose a little, I adjusted till rough, backed off, then a quarter on

Last edited by jduvall88; Oct 31, 2009 at 05:40 PM.
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