oil to the center main bearing

[tvpear12]

I can see the 2 oil holes in the intake that deliver oil to top and bottom main bearins but how does the oil get to the center main and where does it come from? 1989 90 horse v-4 cross flow.

 

[jimmbo]

Re: oil to the center main bearing

Oil that falls out of suspension coats the walls of the crankcase and other internal parts and eventually runs down into the bearings. Oil that collects at the bottom bearing is blown, by crankcase pressure, through the recirculation lines up to the top bearing.

 

[tvpear12]

Re: oil to the center main bearing

There is a small brass colored oil orfice in the center of the case that looks like it would feed oil to the center bearing, Where does that hole lead to in the piston side of the case?

 

[Dhadley]

Re: oil to the center main bearing

It starts in the bottom of a cylinder. As the piston goes forward (toward the intake) it forces gas/oil to the center main. There is a tiny rubber piece in there that acts as a one-way valve. <br /><br />During a rebuild a lot of dirt and debris collect in this tiny passage and is overlooked in the cleaning process more often than not.