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?

[Signature620]

How old is your oil filter? It may be plugged. Did you 100% refit the oil pump regulator plunger in the same orientation it came out in? If fitted backwards, all pumped oil will be returned to the oil pump inlet. Did you have the oil pump housing apart other than the regulator?

[Brock]

When I shimmed my pump, I had a issue and still do. When I start my truck cold it will go to 60psi but warm it's under 20. I updated my oil bypass plug and spring as weĺl. No one here had any idea why........

[PeteMelb]

(04-11-2018 )pearce trucking Wrote:  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?

Not sure what your issue is but one thing I did notice in your thoughts was your comment regarding the bypass valve replacement. If you replaced the old plastic and spring type with the new type thats a spring inclosed in a steel tube with large Orings at either end (I know Rawze has a picture of the two types somewhere) this should have fitted snugly and not been able to rattle around.

[pearce trucking]

(04-12-2018 )Signature620 Wrote:  How old is your oil filter? It may be plugged. Did you 100% refit the oil pump regulator plunger in the same orientation it came out in? If fitted backwards, all pumped oil will be returned to the oil pump inlet. Did you have the oil pump housing apart other than the regulator?

Oil filter is brand new. 99.9999% Yes on orientation. And no I didn't have pump apart other than the regulator.

[pearce trucking]

(04-12-2018 )Brock Wrote:  When I shimmed my pump, I had a issue and still do. When I start my truck cold it will go to 60psi but warm it's under 20. I updated my oil bypass plug and spring as weĺl. No one here had any idea why........

I assume its under 20 at idle and not going down the road? Do you get oil pressure alarms? Idle pressure under 20 is ok to a point. I believe in the teens at idle is normal. What is your pressure going down the road?

[Rawze]

(04-12-2018 )Brock Wrote:  When I shimmed my pump, I had a issue and still do. When I start my truck cold it will go to 60psi but warm it's under 20. I updated my oil bypass plug and spring as weĺl. No one here had any idea why........

60 cold with it shimmed is normal.

Shimming the oil pump does not cause the pressure to be higher at idle once it is warmed up. The pump simply does not have enough volume to do this at idle. If it is below 20 at idle, then check your rod/main bearings and other things that could cause pressure to fall off.

[Rawze]

(04-11-2018 )pearce trucking Wrote:  ,...
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.
...

You did something very wrong!. I have never seen 80-90 PSI oil pressure in an ISX not even with it shimmed with 8 dimes.

You could have caused some damage somewhere or blown out/collapsed the filter?

Maybe check the pump for damage.

[stevesparts]

Well just a thought... you might want to check and see if something is hanging up in the oil pump..(spring dimes o-ring messed up) i know sounds unlikely but you never know.