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Discussion Starter #1
Hey y'all,

I have a 81 with a 300 straight six 4.9 litre with 93,xxx miles on it. Im getting about 6 miles to the gallon, blowing smoke out of the exhaust, blowing oil and thick smoke out of the pcv on top of the head cover and back into my intake.


My guess is, and please correct me if im wrong, that im putting way too much fuel into my cylinders, that unburnt fuel is mixing with the oil and washing my oil out of the cylinders, producing all those problems listed above. If i tune my carb correctly, will I still have those problems?

Thanks for your help and input in advance.

Probee
 

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is your oil pan making oil?

a torn fuel pump diaphram can dump fuel in the crank case.

or you could have a bad cyclinder. run a compression test and post the numbers

whats your plugs look like?

last complete tune up?
 

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Discussion Starter #3
i just bought the truck... a sfar as i can see the only thing that is leaking oil is the (you guessed it) the rear main seal. (ughh:doh0715:) i dont get what you mean about the fuel pump diaphram
 

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your fuel pump uses a diaphram to pump the fuel to the carb, if it cracks it can dump fuel into the oil pan since it has direct access to the inside of the engine because it runs off the cam shaft.

like I said, are you making oil in the crank case? does your oil smell like fuel and is it thinner than oil?
 

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Discussion Starter #5
yes and yes
 

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Sorry to say, but single digit economy and the symptoms you describe are the typical death knells of a 300-6. They don't die so much as they just kinda peter out and collapse in a pile of their own blowing and oozing oil.

Start with a compression test to see if the engine is even worth throwing a new fuel pump at, if you have good compression then get the fuel and PCV system back in check.
 

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Sorry to say, but single digit economy and the symptoms you describe are the typical death knells of a 300-6. They don't die so much as they just kinda peter out and collapse in a pile of their own blowing and oozing oil.

Start with a compression test to see if the engine is even worth throwing a new fuel pump at, if you have good compression then get the fuel and PCV system back in check.
the 300 I had never burned a drop of oil and got 18mpg, then all of a sudden it decided a wrist pin was going to go out on it. it still ran but sounded like a diesel, so I put in a 302.
 
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