worn cam lobes

[jim90]

I have a '90 E250, 351W engine that had a tapping noise near #4 exhaust lifter area. Top end tear down revealed #4 and #8 exhaust lifters were badly worn concave and cam lobes rounded, #4 more so than #8. All other lifters and cam lobes appear to be OK by inspecting the cam lobes through the lifter openings visually and by feel. I believe the cause is apparently a lack of oil getting to the rear of the engine. To replace the cam (which involves removing the grille, radiators, and everything on the front of the engine) without resolving the cause of the lack of oil would be a waste of time. I purchased the van with a newly installed rebuilt engine in it about 50,000 miles ago. Oil changes and maintenance have been performed regularly. Does anyone have any ideas why the oil isn't getting to the rear of the engine and how I can resolve the problem without having to pull the engine and do a rebuild. The cost of replacing the engine would be more than the vehicle is worth. I'll appreciate any advice offered.

[theoldwizard]

Sounds like low oil pressure, probably at idle. The only way to know for certain is to attach a mechanic gauge directly to the where the normal oil pressure sensor would go and check the pressure from idle up to 3000-4000.

A good rebuilder automatically replaces the oil pump because it is difficult to do once in the car.

[jim90]

Thanks for the info. I can't check the oil pressure without putting it back together, but I suspect either low oil pressure or a blocked oil passage. Either way, I guess it would require an engine OH or replacement to fix it. I expected the engine to go longer than 50k miles. The engine had just been installed prior to my purchasing it.