Testing for oil leaks with air pressure

[51Hog]

Just hooked up the air line to the oil line that feeds the oil pump and ran 15 lbs air to the oil passages. it gurgled and squeeked for about 5 minutes and did not blow any oil out. Turned the air up to 25 lbs and it gurgled and squeeked a little more. I sprayed a mix of 10% dish soap and water all over the engine and kept it wet for another 5 minutes.
The only leak that appeared was on the front inside bolt of the rear lifter block. I know that there is a leak at the inside bolt on the front of the front lifter block also. That leak did not show up.
This leak is coming from the lifter block bolt.
Looks like the bolt hole goes into an oil passage?

pressure.JPG

lifterblock leak.JPG

What is the hole at the base of the front cylinder at the edge of the liftre block boss.
Any chance that it intermittantly leaks a lot of oil?

lifter block boss.JPG

[mbskeam]

oil galley, this has a plug in it at the lifter block area...
does the rear front bolt go into this oil way?

[Panacea]

Maybe the welch plug is leaking at the end of the oil passage. See if the air comes up out of the lifter block bolt hole, if it does you could probably just use a bit of teflon tape next time...

[51Hog]

oil galley, this has a plug in it at the lifter block area...
does the rear front bolt go into this oil way?

Don't know for sure. I do know that when the lifter block was bolted to the boss, air came out when I pressurized the system. I did carefully try Teflon tape at one time along with the Teflon pipe dope. I also tried silicone at one time.
Is the "plug at the lifter block area" inserted from the end of the hole that we see in the pic?
Dale

[fourthgear]

After what I went through with my 65 , any thing could have been done by previous owners . I don't think it can go into the oil feed passage . Saying that , ya never know what some one had altered before you got the motor .
I have seen some use perminate sealer on the welch plugs to seal them or replace.
I would check the tappet block decks on the case for trueness & the tappet blocks .
If you are going to use any type of sealent (rtv , etc), any thing it touches must be free of dirt & OIL ( I use Acytone )or it will not work for long & of course proper set time .

[mbskeam]

ummm......
you should pull this engine apart...
your case may be cracked... crank run out.....
this crack will run up from the lifter bushing bore up towards the deck, right thru the oil galley that feeds the top end....
you can use lacquer thinner and a air nozzle, this stuff will find a crack real quick when under pressure......
this is what happened to mine......
it can be fixed......

[51Hog]

I am pulling it apart. Going to work over the cases and take the crank in to the guys that put it together.
They are going to true it and replace parts as necessary. They are planning a 60% balance factor.
Thanks for the heads up on the possible crack.

[51Hog]

I pulled it apart. Lucked out and found no visible cracks in the case. Just the broken mount.
The oil leak at the front of the rear lifter block is caused by what appears to be a broken lifter block screw.
It is the front inside screw that is over top of the oil galley. Looks like someone broke a bolt, tried to drill it out and missed because the drill could not be located vertically over top of the broken bolt. The bolt hole does go into the oil galley. I don't think that it would hit the galley if it were not drilled at an angle and deeper than necessary. The hole is off set from where it should be by approx 1/16 of an inch and about 1.5 degrees off from vertical. Think I will remove the broken bolt, plug the hole with threaded aluminum rod, re-drill and tap for the lifter screw.
Look closely at the pic and you can see the edge of the original hole.

[doc308]

This is amazing. Just today, I removed the lifter blocks from my '48 pan and was wondering about that same hole myself. I'm a little confused here--is it supposed to be plugged or not? The hole doesn't seem to lead anwhere from what I can tell. I probed with a small pick and the hole seems to dead -end. What the heck is it there for?

[51Hog]

If you are talking about the hole by the center of the front lifter block, It is plugged.
It was put there when the case was drilled to connect the two feed passages that go up through the cylinder bases to the top end. After they drill the hole from the outside, they plug it. You are feeling the plug.
Hope you understand my confusing explanation.

[doc308]

Thanks, man--I get it now.