I just installed a rebuilt motor into my truck and I am having low oil pressure problems. The machine shop put together the short block and then I installed the heads, lifters, valve train, oil pump, and intake. I can get 20 psi when I'm priming it, but when I start it up it idles at 5psi and then drops off to zero. I checked the front oil galley plugs by the timing chain and they were still in. I called the engine builder and he said to check the oil galley plugs in by the lifter valley under the lower intake. I have not opened it yet, but I was looking at some pictures I took and I don't see where any plugs would be. All I see is two threaded holes for the spider and 4 holes for the oil to drain back. So are there any oil galley plugs in the lifter valley? If so where are they?

 

3 plugs in the rear of the block, three in the timing area in front, none that I recall in the lifter valley on a small block. I know there are on an FE and 385 series big blocks.

 

That's all I thought was there for oil galley plugs, and all six are still installed in their spot. Any other ideas what could cause this oil pressure problem on a rebuild?

 

oil filter full of cam lobe........oil pump sump full of rtv.... the wrong bearings

 

A friend had a shop do his 454 chev and had low pressure as well, he found a couple of his screw in galley plugs to have small holes in the middle(were meant for something else) and the shop installed them by accident.

 

Well what I might do is change the filter and prime the engine again with the timing cover off so I can see what is going on around the pump and to make sure nothing is leaking past the oil galley plugs. I talked to the machine shop yesterday and they, at the moment, can't think of why it would have no oil pressure like this will all the oil galley plugs in.

 

There is one under the intake at the rear of the block right at rear cork gasket area.
It is the main oil galley.
Here is a picture

http://www.mustang50magazine.com/tec.../photo_02.html

 

So your saying [IMG][/IMG] that should have been plugged? I was under the impression that it was a coolant line because it was so big in diameter compared to the rest of the plugs.

 

Yes, now that someone mentioned it ive heard of that plug being left out many times

 

Yes it needs to be plugged, i bought one from napa for mine. It looks like a small freeze plug. It should be just below flush with block, you don't want drive to deep that it stops the oil from flowing.

 

Ok, hopefully I can get that plugged up this weekend and get the truck running. Of hand, does anyone know the diameter of that plug? I had the machine shop send me one, but I want to double check the size in case I need to order a different one in. Any tips for installing the plug? I've never put one in and want to make sure it is right.

 

I use a socket that just fits inside the plug, I also use that brown, thick, nasty stuff on the outer edges of the plug, I think it's called permatex gasket maker.....it's real think stuff in a tube....Not sure on the name. I'll check tomorrow when I get to the shop. Works good...

it surprises me you got that much pressure with that plug missing.......

 

The extra one that i have measures 3/4".
You can find a socket to fit inside of it and drive it in with a hammer, lightly, Just hard enough to make it go.

 

Ok, thanks for the help.

 

No, thise were probably meant for just that. Some of those bb chevy's had a issue of having real noisy lifters for a long time on start up - the problem was all the oil drained out of the galleys and it took a long time to bleed the air out once the engine was started. So one trick was to drill small holes in the galley plugs so the air bled out faster - at the cost of a little oil pressure. Your buddy must have had low oil pressure to start with, so the pressure the holes were bleeding was just too much...