I just finished rebuilding my 4.3 for the second time this year and the same thing continues to happen. It will only maintain proper oil pressure when its cold or higher rpms. I have completely overhualed the engine myself. Please help. I put a mechanical oil pressure gauge on it to verify the pressure. I'm about to pull the front axel and gear box to remove oil pan so I can figure this out. If anyone has any ideas please let me know.

 

did you replace cam bearings and what did you do with the crank?

 

Yes cam bearings and crank are new

 

I installed the new bearings after 1 piston rod had spun.

 

100% total rebuild. I am running out of ideas

 

you never said what oil pressure you are running at?

 

1. On your rebuild, did you put a new oil pump in or take it apart and clean it to make sure everything is good to go?

2. Maybe there is a problem within the remote adapters, the oil cooler lines or the oil filter bypass valve?

 

My oil pressure when the truck is cold sits at about 50. When the engine is hot it drops to almost nothing, about 2 to 5 psi. I had purchased a new oil pump for the truck when it was rebuilt. I made sure it was working right and cleaned out. I did some research and found out that vehicles with a remote oil filter system, such as what I have on my engine, it is recommended to run a high volume oil pump otherwise you can lose up to 25% of your oil pressure. I have already torn everything down and will be getting my new oil pump and other parts: shocks, upper ball joints and lower ball joints later this week.

 

I've got the same problem. I'm leaning towards the oil filter bypass spring in the block and or in the front mounted oil pump. Does anyone know the opening pressure, for the one in the block and how to increase its pressure?
Frank

 

The melling oil pump I purchased is about $20 more the the standard oil pump. It should boost my oil pressure back up to stabilize the engine. It says it will boost it to 70 psi and that should be more than enough to make sure my engine isn't starving for oil.