Small oil leak from bolt 4.3 L Merc
 

Does anyone know what this bolt is for? It's leaking oil from the back of the engine block... Location near the oil sender. I tightened it 1/8 of a turn.

Re: Small oil leak from bolt 4.3 L Merc
 

Looks like basic brass pipe plug and bushing. It is probably an alternative oil port for pressure or maybe just a plug for an oil rifle. Tighten it some more or maybe remove it and add some thread seal or Teflon tape if the leak does not stop.

Re: Small oil leak from bolt 4.3 L Merc
 

That's where the oil pressure switch is installed on a 4.3L car/truck engine. You can just tighten it or apply some sealer tape.

Re: Small oil leak from bolt 4.3 L Merc
 

Thanks for the info guys. Maybe I'll install a mechanical oil pressure gage there then. My dash gage is pretty erratic, bouncing around all the time.

Re: Small oil leak from bolt 4.3 L Merc
 

If the gauge is bouncing around a lot, you probably just need a new sending unit. I don't think they are very expensive, certainly not for a car.

Re: Small oil leak from bolt 4.3 L Merc
 

I had replaced the oil sender unit earlier this year with a Teleflex Marine one, but it didn't work at all and sent it back. I'll likely get an OEM one sooner or later, just haven't felt it was that important at this time. Got other maintenance issues to do beforehand.