Cat 3406e Oil Pump

the O-rings may have been pinched if not lubed when installed. fileing the end of tube that bolts to block only if you do it lightly, that one I will agree on, didn't think of it before. one thing to see about is the brand of oil your using. that right there could affect oil pressure. like I said before check the easy things first before tearing into it.

 

Main bearings that new could have been over torqued. Someone could have cleaned everything with red shop rags and have pickup screen full of lint.....not that I know of anyone doing that before hehe.
I would advise the oil pump swap regardless for a new in frame.

 

if you seen that it was bad info or misread. don't! plug oil feed line to compressor unless you want to buy a new compressor.

 

The spec. for oil pressure is 15psi. ( @ idle.) I agree with the responses already mentioned. I will add some far fetched causes. Recently had a crankcase oil filter that was replaced by the owner. The discount filter's pleats collapsed inside . Even though it was recently replaced. Another one. Stuck relief in the pump due to debris. Also debris in the filter head reliefs. Causing excessive oil by-pass. Here's a crazy one. The rocker shafts were installed upside down.( flat sides facing down.) However, the jake brakes will not work if this is the case. The front gear train stub shafts have excessive clearance from damage/ over speed. Plug missing from internal oil galley on new head or jake housing. Broken jake housing. Pump gear missing woodruff key and loose. Wrong bearing sizes. Like I said. These examples would be far fetched. Although I have seen them over the years. Good luck. Probably something simple. I hope.

 

If you put new rods and mains in, put in the new or reman oil pump. It is cheap to put the springs and plungers in the oil filter head too. We put rods and mains in ours and started losing oil pressure after about six months. Always ran 60-65 lbs and finally got to 40 lbs before we decided to do something. Changed the springs and plungers in the oils filter head and gave us five lbs. Changed the pump and got it all back. They wear out like any other component.