CM871 oil pressure

[pearce trucking]

So I finished refurbishing the ifsm. Replaced a timing actuator, the lift pump, a compuchek fitting, orifice plug, anti drainback valves and all sensors, orings, and gaskets. Seems to run good and no leaks.

My problem is oil pressure. I replaced the oring on the pickup tube, put five dimes in the bore, replaced the oil pan gasket and drain plugs, replaced the bypass valve in the filter head, and replaced the oil pressure sending unit. Also I replaced the oil filter and changed the oil. (Rotella)
Additionally I ran the overhead and replaced the jake harness. On the egr tuneup side, I replaced the egr valve, the delta p sensor, the imap sensor, the cam position sensor, and the oil temp sensor.

When starting it the first time, a timing actuator code came up. I checked the harness plug, and it went away. Idle is pretty smooth. Oil pressure went up to 80-90 psi for 2-3 seconds, then dropped back to 40 psi. Thereafter it dropped to 20-24 at 1100-1400 rpms. At 600 rpm idle it dropped to about 8 psi and the alarm came on, as well as red shut down alarm. If bumped above 1000 rpms it would climb back around 16-20. I hooked up insite and verified that my dash gauge and insite were in lockstep as far as pressure readings. I reinstalled the old bypass valve in the filter head. Thereafter oil psi was 0 and wouldn't budge. I shut it down immediately.

My thoughts are as follows:

-I reinstalled the old style bypass valve because I'm unsure if I need the 19mm plug instead of the 16.5mm that I have. This would have allowed oil by as the new valve would have rattled around in the bore. If the filter was blocked the loose bypass valve might have allowed the 8 psi.
-I used a LF9001 oil filter. I'm hoping this is the problem. I'm replacing it tomorrow with the 14000NN.
-It seemed to me as though the exposed gear on the bottom of the oil pump had more lash than it should, possibly as much as 1/8". Maybe the pump is worn out.
-Could the 5 dimes in the bore have caused this?
-I'm going to stick a mechanical gauge on it tomorrow if the filter doesn't fix it.


I was having low oil pressure problems in cold outside temps or when mountain climbing last trip out. That's why I was doing the repairs done to date.

Any thoughts?