Technical 327 oil pressure problems.

Was driving down the road the other day. Noticed my oil pressure was dropping. Pulled over and got towed to the house. Changed the oil and filter. Still nothing on the mechanical Guage. Bought a new Guage and the same thing. If is disconnect the from the rear of the block going to the guage and start the motor oil shoots out of that hole like a struck gold. What could be the issue? When I have the line connected and start the motor I barely see any oil in the line.

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Only takes a pound or two of pressure to squirt out the block. See if you can hold it back with your finger. Anyway a working gauge and a new one both going bad is slim. The old oil was clean? No knocks? Maybe your pickup tube fell out of the pump. See what you can see or feel through the drain plug hole.

 

Remember the basics when troubleshooting a problem. Pressure is a result of resistance to flow. The pump supplies flow, the internal clearances in the engine create resistance resulting in pressure. If you have a loss of pressure you either have a loss of flow or excessive clearance. Clearances will open up as the engine wears, but that usually doesn't happen during one drive. If the engine has had good pressure but all of a sudden it started to drop, then it probably isn't a bearing clearance issue, it is probably a lack of flow. So what would cause the engine to suddenly lose flow? Most likely it's the pump. A slow loss of pressure could be from wear in the pump. A sudden loss of pressure, IMO, points toward the oil pressure relief valve.

An oil pressure relief valve stuck partially open will result in a loss of flow and a loss of pressure. Contaminants can get into the valve and cause it to stick. Wear can cause the valve to stick. Excessive varnish deposits from over extended oil changes can cause the valve to stick. A broken spring can also cause the same problems.