Oil Pressure

[kork340]

Hey all, I got a problem with my 318. I have 55psi on start up, cold. Once engine is to operating temp. I have only around 8psi at idle. I checked it with a hand held fluid filled guage as well as the one I installed, and it's the same, so that rules out a bad guage. Running down the road at 1800 rpm it's at 10-15psi. I have the engine out and have rechecked the bearings, all OK. I just put this together about 1000 miles ago. New rings, mains and rod bearings, cam, lifters, springs, valve seals, timing chain, oil pump, etc. Just a basic overhaul. I did compression test and all cylinders at 130-135 cranking the engine over 3X each cylinder. Have oil at rockers, no noise, but I do have a slight knock at idle when the oil pressure is real low. Bad pump? Any other ideas?
Thanks.

 

[340mopar]

There is a plug in the oil galley that almost always gets left out at the rear main at rebuilds. It could be this, it pumps oil right back into the pan. If I remember right if you remove your oil sending unit and put a peace of 1/8" gas welding rod or wire down the hole it should hit the plug at 7 1/2" - 7 11/16" if not you will have to remove your rear main cap and install it. It is a press in plug like a shot plug and goes in 2 1/8" - 2 5/16" in from the bottom of the block. Make sure you use a stud locker loctite so it can't come loose.

 

[cavemanmoron]

There is also another; rear oil galley plug;
it got left out on a
machine shop cleanup, on a 340 I rebuilt.

I noticed oil pouring down the dist/oil pump shaft area, when using an oil pump primer, with an electric drill.

There is an Outer plug, that has to be removed to access the inner plug.

Sorry, no photo of the inner rear plug.

I made Sure both the oil plugs were in the 318 when I rebuilt it.

 

[perfacar]

hi, at the back end of the left rear oil galley ,there is a plug required.most people forget to install it back in motor. all you need to do, is pull dist, use a small mirror and light ,look down in there. I have seen this same thing before
and turned out to be missing rear oil galley plug. leaving out the one in bottom of block, would have no pressure and you would have lost the bearings before now.