Blown oil filter - no pressure on gauge?

[47convert]

Anyone ever seen this problem? I'm thinking the pressure relief that's built into the oil filter adapter (Small block Chevy) is stuck. This is a 0 mile rebuilt 350 Chevy that's been sitting for about 7 or 8 years without being started. I ran the oil pump on a drill for a couple of minutes and the engine started without turning over a whole turn, but oil poured out of the top of the filter. Figuring that I hadn't tightened the filter enough, I cranked it in another turn and fired the engine again. This time I had a guy watch the oil pressure gauge, and when it remained at 0, I shut the engine off after just a couple of seconds. This time the filter blew up like a softball! I'm thinking the oil is getting pumped to the filter but can't leave there and so it balloons the fiter and leaks at the seal. Any ideas?

[enjenjo]

The pressure relief valve is built into the pump on a 350. The valve in the filter adapter is a bypass valve for the filter itself, in case it gets plugged.

[34ford]

This is from the SRS board where Steve posted this answer to a low pressure reading. Maybe he might chime in here.

"From the anals of my tech page. Maybe some help?

Trouble Shooting Some Basic Oiling Systems

Trouble shooting ills of the oil pump sometimes is difficult and not an exacting science because the symptoms are vague and overlapping. Here are some basics for helping diagnose those problems.

The relief valve in an oil pump has spring pressure behind it to determine when it will open. If it is designed to open at 50 PSI, this valve does not have any affect on pressures below that figure unless it sticks in the open position. If it does stick open, the result could/will be a very low idle pressure but builds easily to higher pressures and may/frequently exceed the high-pressure range of the valve in the pump. If your pump suddenly reads a lot higher at high RPMs after reading low at idle, this is probably the problem.

The relief valve can also stick in the closed position and the results of this is that it won't let excessive pressure release inside the pump which means the pressure will build until it ruptures the oil filter. If your oil filter bursts then the pump is likely the culprit.

If the relief valve is just sticky, not stuck closed or open, whereas the movement of the valve is somewhat restricted, this produces an erratic oil pressure observation.

If an engine has excessive clearances in anything but rod bearings (remember the oil galleys to not change volume), the oil pressure will be uniformly low throughout the RPM range.

Rod bearing clearances that are excessive show in low idle pressure and will actually get worse as the RPMs goes up. This is a result of the centrifugal force pulling all the oil out of the bearing surfaces and of course the more RPMs, the more centrifugal force, the more oil gets flung off.

Foaming of the oil is usually related to too much oil in the crankcase and is not pump related. What happens is that the crank and/or rods churns up the oil introducing air to the oil, which makes for poor oiling pressures and volumes. Fluctuating oil pressure readings can be a sign of this due to the air introduction.

Small irregularities in pressure readings can be associated with airleaks at the pump since air is compressible. Usually this leak appears at where the screen is mounted to the pump.
--
Steve "Jack'Stands" Jack

[47convert]

I know you're right because we used to play with spring pressures when we were kids, but I can't understand why the pressure at the filter is high enough to blow it up, but very low at the (mechanical) gauge. The RPMs have not reached anything higher than idle because it started so quickly and we noticed oil on the floor before we could adjust the idle RPM for cam break in. The oil pressure gauge is fed frpm the normal location beside the distributor.

[47convert]

Found the problem this morning - the threaded filter adapter was broken and 1/2 of it must have spun on it's mounting screw when the filter was tightened, causing the filter seal to be very close to the edge of the bore. It must have blocked or partly blocked the exit port causing the oil filter to expand, untill the seal blew allowing the oil to escape onto the floor - never saw anything like this before.