MERCRUISER MCM140 running good but seems to have gas in the oil

[Sullysllvn6]

I have a 1985 Mark Twain with a mercruiser mcm140 4 cylinder engine. I have been working on getti g back on the water. I had it on the lake this weekend and it seems to be getting gas in the oil. I recently rebilt the carb and mechanical fuel pump. The oil is grey looking and smells of gas. I have seen water in oil before and it always looks milky white but this has a grey tint to it. The boat ran really well it did not get hot,but i found oil leaking from the front seal a little and pulled out of water. My question is if the block was cracked would the boat still run well and with the oil having a grey tint instead of white is it gas or water? Also if i rebuilt the carb and fuel pump what else would cause gas to get in the oil or do you think it is water and possibly a cracked block. Thanks for any help

 

[Scott Danforth]

welcome aboard.

if there is gas in the oil, the 3 initial posible reasons are

bad fuel pump (leaking gas into engine crank case)
bad fuel pump (leaking and running up the clear hose into the flame arrestor)
bad carb (running way too rich)

 

[Sullysllvn6]

Thanks I just rebuilt the fuel pump and carb, but the carb I am thinking would be better just to replace. The oil looks to be a grey color and not milky, does this sound like gas or water getting in the crank?

 

[williemon]

You could still have a gas dribble from the carb when the engine is off. A float and needle seat not sealing off the fuel flow properly could over fill the float bowl and the end up dribbleing some fuel into the cylinders

 

[Sullysllvn6]

Ok guys fixed my fuel problem with a little adjusting on carb. Now it seems like I am lacking in low end power. After the boat planes it run fine but just takes forever to get it there. What would it do if I had prop issues? Any suggestions?