Reply To: Oil Pressure Relief Valve Spring

[Gregory Long]

Hello Bruce, and welcome.

The pressure relief spring often has an unfinished end. I usually put this end into the hollow in the cap screw/bolt that encloses the spring.

Oil pressure is not what keeps Pierce Hydraulic lifters pumped up. The check valves inside the lifter assembly catch and trap the engine oil, and if these are leaking, then the valves will clatter.

Your oil pressure should be around 10#-15# at a hot idle, using 15w-40 Rotella T oil. Lower oil pressure at idle is not a product of the relief valve or spring. The relief system only controls maximum oil pressure. Most 8cylinder engines will run at 30# to 40# at 30-40mph in high gear if the engine is in good shape..

If the oil pump is worn, and the engine bearings are worn, then you will not have your relief valve open at all, the excess clearances will let too much oil through to build up pressure.

An engine can run for a very long time as long as it has some oil pressure, and the engine is not called on to produce a lot of rpm and power.

Greg Long