Hi. Thanks for using JA! I will try and help you out.
It is possible that you engine may need rod and main bearings. From my experience, cam bearing do not give much trouble on 3406B engines.
Are there alot of miles on this engine? Do you know when the last time it had a lower end overhaul?
The good news is your oil pressure is still within specifications. The minimum oil pressure spec for your engine is:
15 psi at idle
40 psi above 1200 RPM's.
Please let me know if you have any more questions.
Thanks for getting back so quick. Motor has 1,180,000 miles on it (GO CAT!)
Verry little blow by out crank case vent. No smoke at all from stack.
Had rod and mains done, about 850,000 miles. About 270,000 miles on bearings now.
Seams the low psi came kind of quickly. Maybe 15,000 miles from normal to low now.
In review idle cold, 45 psi, hot 22 to 28, depents on water temp.
1900 rpm cold 80 psi, hot 54 to 56, " " " "
Thanks for the information.
Wow. That is great. You sure can't get over a million miles on todays engines.
I would probably monitor the oil pressure for a while. Like I said, the oil pressure is still within specs.
Did you have the oil pump replaced also when you had the main and rod bearings replaced?
If you did not replace the oil pump last time, I would want to try an oil pump first.
Since 15 and 40 are the minimum oil pressure, I wouldn't worry until your engine hits one of these minimums.