What is this? Oil Pressure Guage?

[Harmon]

What is this on the back of my block?  I think its for Oil Pressure?  The thing is do I have 2 of them and why would I have that?

I had a big leak in back of block, and I am wondering if this is where it was leaking....Can I unscrew the cylinder that is going into the block?

Thanks for any info!

[zieg85]

The bigger one is the oil sending unit, the other one makes up and gives power to the electric choke...I think

[bd]

...I had a big leak in back of block, and I am wondering if this is where it was leaking....

A leak from that area is often the rear valley seal between the intake and the China wall.  If you do unscrew the oil sender or switch, be sure to support the brass stand fitting with a stout wrench, because they are prone to snapping off.

[Blazin]

X2 on what zieg said. I have seen the actual sending units leak oil through them. It could be the rear intake gasket as well.

[81_Chevy]

x3

just replaced it on my truck. stopped the oil leak.

[Harmon]

Thanks yall...hey 81 chevy, you replaced the oil pressure guage?  Or intake gasket?

Also does the cylinder thing goin ginto the block un screw? 

[Blazin]

It will thread out, but you will have to remove the sending units first. Its 1/4 NPT, when you re install it use pipe dope on the threads, also on the threads of the sending units.

[zieg85]

1/8"

[81_Chevy]

Thanks yall...hey 81 chevy, you replaced the oil pressure guage?  Or intake gasket?

Also does the cylinder thing goin ginto the block un screw? 

i replaced the oil pressure gauge sending unit. it just unscrews. take it down to a local parts store and they should have a new one in stock for under 20$