Caterpillar 3406 b/c engine problem

GENERAL DATA OF THE TRUCK:
PETERO BILT MOTOR TRUCK 3406 B/C First generation semi-electronic “hydraulic injectors”.

DESCRIPTION OF THE PROBLEM:
When lighting the truck in the morning, it lights the low oil pressure is 60 and the RPM are 600 and 700. If after turning it on it does not turn off the engine does not give problems throughout the day. When the equipment reaches its optimal operating temperature “180 ° C” and its oil pressure is 40 and the RPM are between 1400 and 1500.
If for some reason the truck had to go out when turning on again is when it begins to fail. The symptoms it presents are the following:
1. Start to oscillate
2. It is lit Chek Engine
3. Flash code 24

after 5 minutes of presenting these failures the engine is automatically turned off, if after the power switch is extinguished, it is placed in the position of OFF and try to turn it on again the machine turns on without any problem, if in the lapzo of an hour the fault does not appear again. The fault all day.

The machine does not pull smoke, does not spend diesel excessively, all maintenance sevices have been given such as:
1. Oil change, a “15 w40” Mobil brand was placed
2. Original filters of both diesel and oil
3. Cleaning of ECM connectors to all sensors
4. Change oil pressure sensor for an original

one Failures, the seller commented that the engine was recently repaired, but when the test was never turned off and turned on. The engine had a year stopped without being used and without batteries put.
When transferred to Mexico, the cruise speed was going to fail, then I stopped working the engine brake, this last work suddenly and then stops working for other days, this failure is unstable.
He scanned and only presented a code saved a long time ago being this code on 24, and also presented an active code being the same 24, after detected these codes was proceeded to erase them and the batteries and sensors were disconnected for 4 hours. After this time, the engine was turned on and I did not present any fault. When the machine turned on again in the morning, the Code 24 was presented again and the engine was turned off again.
In addition to the services, the following revisions have been made:
1. Carter was removed and silk pump was checked, this impurities being free
2. Pressure relief valve withdraw, it presented a slight change of color in the metal in the middle part mirror to opaque as rake with a very fine lime.
3. Rondanas were placed between the spring and the embolo this to give a bit of “counter-pression” in the relief valve was closed and the engine was turned on, the pressure rose from 60 to 75 in cold and 40 to 45 at optimal working temperature, and the meor was governed at 1800 rpm since it was not previously governed.
Even after performing these reviews and small change the engine continues to go out. The temperature never exceeds 190 ° C, ducts and diesel tanks were cleaned.
Question:
This type of pump works with the internal pressure of the engine. If there was an internal oil pressure leak on any stamp of the pump, could you try that the ECM interprets it as a serious problem of low lubrication precion and man give the motor off signal?

Note:
The physical marker marks good oil pressure at the time of presenting the fault and yet in the display I am shown code 24. If the physical marker is not consistent with the flash code that indicated to me the code 24?
Which of the two indicators is right and what is wrong?