oil in carb

tgjohnson1

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Feb 21, 2010
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18
Hello everyone. Can someone give me an idea as to why I would be getting oil in my carburetor? It is in a 93 Bayliner with a 4.3LX and a Weber 4 barrel caburetor.
 

Bondo

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Apr 17, 2002
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71,082
Re: oil in carb

Ayuh,... My guess is the Rings are Shot,+ the blow-by is carrying it into the carb from the vent tubes...
 

tgjohnson1

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Feb 21, 2010
Messages
18
Re: oil in carb

Thanks for the fast response, but its coming from the bottom. That is kinda what i was thinking anyway. The vent tubes were not even hooked up. Does that make any difference?
 

Kainon

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Sep 13, 2009
Messages
608
Re: oil in carb

Oil coming from the bottom now that's interesting. The tubes should be connected to the Flame Arrestor. I recommend a compression and vacuum (at the carb/manifold) check of the engine and go from there.
 

tgjohnson1

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Feb 21, 2010
Messages
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Re: oil in carb

I guess the question is, is there anything else that will cause that to happen besides the rings? Timing, valves or something like that.
 

Kainon

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Sep 13, 2009
Messages
608
Re: oil in carb

nope, that about does it. oil goes to the top of the engine ( rockers area ) by way of the Push Rods from the lifters, from there some goes back to the pan by way of the drain holes, and the rest ( very little) dribbles onto the valve stems, to keep them cool and lubed. and if you have bad seals gets sucked into the engine and burnt off. then if you have a firing order problem or cam timing problem and air goes back to the carb, then you would have some oil there, and fuel.. That can sometimes be checked by putting your hand or a rag over and see if it moves. Which Is why i recommended a simple compression and carb/intake vacuum check as you can watch it more easily as vacuum in the intake changes it shows on the needle, there are instructions in Motor Manuals how to read Vac gauges.
 

Howard Sterndrive

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Nov 5, 2008
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4,603
Re: oil in carb

at wot, several hundred cubic feet of air travel down the carb throat each minute, at several hundred miles per hour.
how could oil travel opposite that breeze?


what is the operational problem?

is it backfiring?

did a neighbour dispose of his used oil in your gas tank?
 

tgjohnson1

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Joined
Feb 21, 2010
Messages
18
Re: oil in carb

It is backfiring, I think from the timing issue. But something new happened yesterday will running it. What would the oil cut-off switch have anything to do with how the motor idles. With it bypassed it will start and idle 10 times better.
 

a70eliminator

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Sep 9, 2007
Messages
3,762
Re: oil in carb

The only way for oil to get into the carburetor that i can think of is through the vent tube off the valve cover, the oil drainback holes got plugged and you valve cover is filling up with oil, the oil not returning to the pan is causing low oil cutout switch to activate, Just my imagination running it's highly unlikely but could happen, I've witnessed some pretty weird stuff.
 
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