1956 Cadillac 365 oil pressure issue

Found a 1/2" plug.....made an installation tool and installed it in the hole. Went in a little to easy but the 7/16 plug was to big. I have 35 psi oil pressure using my cordless drill to spin the oil pump but the plug leaks. Guess I'll just run it around the driveway until it blows out then try something else.

 

Going to put it back together tonight and do the cam break in. Hopefully that plug will stay in long enough for that at least. Before I do that though I'm going to try a couple things to try and make that plug seal a little better.

 

Have you checked to see if your oil filter bypass spring and assembly is stuck in the open position ? If this hole isn't threaded, it's hard to believe there was a pressed in plug with a small hole to oil the dizzy. I think you were on the right track when you said it might be the outlet for the oil filter bypass. Now if this is the case, you might have the wrong oil filter or there is a plug downstream of the filter.

 

This motor just has an add on partial flow filter. It doesn't have a regular full flow type filter. In fact, the tubing going to the remote mounted oil filter canister is about 1/8" tubing. The hole is the end of one of the horizontal oil headers that runs to the front of the motor. Tonight I'll try sticking another plug in that hole and crank it up and see what happens.

 

That sounds kind of hinky, doesn't it?

I'm thinking 1/8" is the size of tube that usually feeds a mechanical oil pressure gauge. That just seems awfully small to be supplying any real volume of oil to a filter.

 

Yep....kinda worthless ....might have to modify that. It might be 3/16" but still it seemed pretty small. I don't remember any of my other past cars having line that small. Maybe that was one of the "custom" additions done by the same guy that sprinkled glitter all over the fresh underhood paint. Now that I think about it more I think it is 3/16".....I even had to replace some 1/4" fuel line and fittings someone put on there.

 

Your oil lines to your filter are all stock and the brass fitting in the block that goes to the line to the inlet side of the filter should have a smaller hole drilled in it that works as an oriface to bleed off oil to the filter but keep up the oil pressure in the system.
There should be a small diameter core plug that can be seen looking down the Distributor hole on the forward side of the hole.This seals off the oil gallery to the lifter port that runs down to the front of the motor.If this is missing there would be no oil pressure and oil pouring into the distributor hole.On the rear side of the distributor hole there is a larger core plug that is fitted via the rear of the block,Sealing it from atmosphere.
If oil is welling up in the distributor hole while you are driving the oil pump off the drill it can only be pouring out the hole where the small diameter core plug should be.
The oil pump relief poppet relieves internally back into the suction side of the pump so this oil you are seeing in the distributor hole cannot be from the pump relief.
I hope this helps.

 

Thanks....yes that's what I was looking for concerning the hole at the rear. I have that part pretty much figured out now. Good info on the oil filter also. I may try increasing the hole size on that oil filter line if my oil pressure is 30 psi or more when it's warmed up. Would like to filter a little more oil if possible.

 

Wow, I'm about 4 years late to the party, but having just had my 56 365 rebuilt and reading articles, I noticed my machine shop left out something very important that I understand kills any oil pressure to the top end...

There is a felt washer/gasket that goes on the tube of the oil pump intake. It's about the diameter of a quarter. If you don't have that, the oil pump can suck air and not build pressure. Hope this helps somebody one day