What are the small machined holes on the backside of the cylinder head?

lndwarrior · #1 10-22-2016, 04:57 PM

Engine is an O-235. On the backside, of the cylinder heads themselves, on the bottom, there are +/- 3/8" diameter holes. What are these and what is their function?
Tia
Gary

n82rb · #2 10-22-2016, 05:08 PM

Thermocouple wells for Cht probes

Bob burns
Rv-4 n82rb

lndwarrior · #3 10-22-2016, 05:21 PM

I'm chasing down an oil leak and it almost looks like it's coming from one of these holes.

Is there any logical reason for this, short of a crack in the casing?

Toobuilder · #4 10-22-2016, 06:01 PM

If its on the "back" (or front), its probably the holes for the barrel nuts that are used for the baffling.

lndwarrior · #5 10-22-2016, 07:05 PM

Quote:

Originally Posted by Toobuilder

If its on the "back" (or front), its probably the holes for the barrel nuts that are used for the baffling.

It's the hole at the base of the cylinder head, next to where it attaches to the cylinder barrel.

PCHunt · #6 10-22-2016, 07:21 PM

A photo might help.

az_gila · #7 10-22-2016, 07:57 PM

Some random pics off the internet...

The holes outside of the rocker cover are for the side (fore and aft) baffles

The hole under the spark plug hole is a well for the CHT probe

The hole just under the rocker shaft hole is for the baffles that go across the engine compartment

lndwarrior · #8 10-22-2016, 09:53 PM

Quote:

Originally Posted by az_gila

Some random pics off the internet...

The holes outside of the rocker cover are for the side (fore and aft) baffles

The hole under the spark plug hole is a well for the CHT probe

The hole just under the rocker shaft hole is for the baffles that go across the engine compartment

Great pics. The hole is the cht probe hole.

snopercod · #9 10-23-2016, 04:43 AM

A rocker cover gasket is a very common place for a leak.

sblack · #10 10-23-2016, 01:48 PM

The hole in the back of your head is to plug into the Matrix.