Is this important? Engine block oil pathways

[Snelly]

So I had some engine problems which turned out to be a blown head gasket between cylinders 1 and 2, which surprised me because before it was always between 3 and 4.

 

I thought I had rod bearing problem, it sounded like piston to head metal clanking sounds, really nasty. I'm not sure what's going on with this engine.

 

Now I will get to my question. The pictures are of another block I have(the original block that came with the truck and yes I've been dragging it around for years),

 

Anyways, the hole that the pin vice is pointing at, it's not a hole. Is it supposed to be a hole? Is this an optional hole? The other block I have it goes to the oil pressure sender and the other way goes into the cylinder head. The block in the pictures only has an idiot light, Is this why I have a hole thats not a hole? I looked at all my manuals and couldn't find anything about the path the oil takes through the block. It's a Z24, but you guys prolly already know this.

[datzenmike]

It's called an oil jet but is just a restriction in the oil feed up into the head to lubricate the valve train. It shouldn't be drilled as the hole size is calibrated. The head does not need much oil so it is restricted and quite small.

 

 

For your head gasket problem...

 

 

Make sure the head surface is flat. I have a large straight edge and place in an X across the length of the head and try to fit a feeler gauge under. You are allowed up to 0.004" any more and the head should be resurfaced.

 

Head bolts are totally reusable but they and the threaded holes should be clean.

 

Tightening pattern is...

 

R  A  D

8.......7

4.......3

2.......1

6.......5

10.....9

 

Using the above pattern tighten to 20 ft lbs, then 40 ft lbs and then to 60 ft lbs.

 

To prevent future head gasket failure, once a year when the engine is cold, loosen one head bolt and tighten to 60 ft lbs. Only when tight move to the next bold and do the same. You can do in any pattern you like but only one bolt loose at a time.

[Snelly]

Oh wow, thanks for the great response. Were you on the old Datsun/Nissan msn group, you name looks familiar. 🙂

 I guess it looks like I was drilling it, but I'm just trying to clear the passage.

Can  I remove that jet and snap it back in?  What ever is in there wants to break off that drill bit. I tried guitar strings(026 D), the manual I have doesn't tell me which guitar string to use.........so I'm a little pissed about that......

 

All these years I thought the reason I burnt up a head on this block because I didn't prime the oil pump, but the short block is fine so it must have been this blocked passage below the oil jet. I wonder what is in there?

[Crashtd420]

It might be a good idea to pull the oil galley plugs at the front and rear of the block....

Check for anything.... then try some compressed air down the jet....

[datzenmike]

Take the oil pressure sender out and blow air in the jet hole. The sender is directly below the jet so if not blocked, air should come out.

 

The possible blockage could also be in the head. There is a gallery running the length of the head feeding the four cam towers. The middle two towers let oil onto the hollow cam which is drilled to oil the lobes.

 

 

Don't remove the oil jet, 11047-21000 it would have to be replaced as it's pressed in. The hole is sized to restrict excessive oil flow to the cam so don't drill it larger either.