Thread: 1966 396 low oil pressure

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Hi I have a 66 396 that was rebuilt when I got it. The warmer it gets the less oil pressure it gets. I just tore it down. And see nothing wrong ,the cam has the groove in the rear journal, cam bearings look new, rod and main bearings look new has melling hv/hp oil pump. Oil pressure drops to 5 psi at idleand goes up to 40 when it take off.

What viscosity oil are you running?

Tried 10w30 and straight 30 no difference

first i would get a good mech gauge to make sure on pressure. low pressure means less restriction . the fact it comes up means the pump is doing it's job. if you loose pressure hyd lifters will tell you asap .

2 different gauges fittings and hoses same readings. And no noise out of lifters they look new no scaring same with the cam

I forgot to put a plug in one of the oil ports by the timing chain once. That made for some low oil pressure.

Everything else being equal, I'd bet a stock pump would help to or cure your problem.

I'll bet a high volume pump would fix it.

bearings look new???????????? doesn't quite tell what you got for clearance!!!!!!!!

This is a long shot. but once I assembled a new engine, with a new Melling oil pump. When I ran the engine it only had about 30 psi. It turned out that the oil pump bypass valve bore had a burr in it from the machining tool. It was holding the bypass valve partially open.

Mike or plastigage all the main bearings and mike the cam bearings.

since the motor is torn down it's pretty much a mute point now. a rebuild will solve it .