I'm open to suggestions on what/which oil pump to use in my '86 2.8 V6. I put a new Melling pump in 34,000 miles ago along with new rod bearings, and it's back to dropping to 0 psi when I come to a stop and it knocks once its warmed up. I've kept the oil changed every 3000 miles, and I dont run it low. Surely there must be a better pump out there...right? Should I go with a high volume pump, or is there a better brand, I thought Melling was a decent brand for pumps.

 

How many miles on the motor? I wonder if bearing clearance in other spots has worn down enough to promote low oil pressure, and you're getting a knock because the pump can't push enough oil at low rpms to keep the motor lubed well.

How bad was the old pump? Gm used pumps with aluminum covers in the early 2.8's, and they wore out fast. I wonder if that old pump caused something else to wear out pretty badly...

I have the same problem, minus the knock. The oil pressure drops to 0 when the motor's hot and i'm idling at a light. Scary stuff. If I'm stuck in traffic, I'll put my foot on the gas to raise it a few hundred rpm to get some pressure up.

Past that, I can't help much more... maybe you should ask this on the Tech board!

 

are you sure the oil gauge is reading right? if you put in another pump, go for a high volume, not high pressure pump.[COLOR=skyblue]

 

The engine has 184,000 miles, but the crank was turned not long before I bought it. I changed the rod bearings when I put the new pump in and the ones I took out were oversized (.010) and looked brand new. The old pump was the worthless aluminum cased one. I've really babied this engine and kept the oil changed, I cant see the bearings being bad already, but stranger things have happened.

 

The gauge is reading right because the knock shows up when the pressure drops.