Rebuilt Engine lost oil pressure mid Break-in

[PAWGEdward]

Hello,

Just got my rebuilt 2.9L running today in my 90 ranger and I started the break-in process for the cam, It was all going well until 12 minutes in the oil pressure dropped to around 30-45 at 2000 and 5-10 idling. The engine was running rough when it dropped and better as it raised.

I am wondering what you all think this could be, I was thinking maybe i got a faulty oil pump (replaced it during rebuild) or the gasket on the oil pump went?

Im not really sure, but I replaced everything but the crank, connecting arms, and some parts of the valve train.


Thank you

 

[drsvox]

Depending on how much RTV you used on the pan gasket, one possibility is that using too much can cause the excess sealant to break off in clumps and clog the pick up to the pump.

 

[PAWGEdward]

I was pretty careful with the RTV because I knew that was a possibility, but since I was careful with it, I completely forgot that could be an option, so I will definitely look for that when I go to pull the pump.

 

[kimcrwbr1]

I hate to say it but it sounds like crank /connecting rod bearings to me. When you have the oil pan off pull a couple of the main bearings and plastiguage them. Maybe drain a quart of oil out and put a jug of lucas oil stabilizer in and see if it improves. Putting new/rebuilt heads on without going through the lower unit is allways a gamble. How hot was it getting could also be a factor. Is the thermostat new did you properly burp the motor.

 

[PAWGEdward]

I did change the bearings during the rebuild, the old bearings and the crank looked and felt polished still. I did not plastigauge them though as I did not know about them at the time. So hopefully that isn't the problem, but I think I will check while the pans off just incase.
It has a new thermostat, but it never reached the temperature needed to open it before problems occurred and now I have pressure issues with a cold start also.

 

[PAWGEdward]

As an update, I went to pull the engine to inspect everything and there was antifreeze in the oil, so my problems were probably caused by a blown gasket. havent got the engine apart yet