Low oil pressure on inline 6 flathead

[Phil Kelly]

I'm having a bit of trouble with my 1947 Chrysler Windsor. Cold start, I have around 20 pounds at idle. Then it drops to 0 and stays at 0. Idle and cruising. At first I thought it was my gauge, but after a quick check with a modern one, it does the same thing. So I was wondering what could be my problem and what are the normal readings because there is nothing specific in my manuel about oil pressure.

[Merle Coggins]

20 psi at idle isn't bad, with hot oil. Cold oil will usually net around 40-50 psi at idle and possibly slightly higher at higher RPM. If you have 0 at idle and while cruising when warmed up you have a problem. You could have a oil pressure relief valve stuck open. This is located along the lower block skirt near your oil dip stick tube.

[plymouthcranbrook]

My 52 Plymouth holds about 45 psi hot or cold.. Idle sometimes on a hot engine goes to 20 or so. Never lower. Using 10-40 conventional oil

[Dodgeb4ya]

Is the new gauge hooked up after the rubber flex hose or before directly to the block? The rubber hose could be swollen closed.

As mentioned also check the pressure relief valve and the oil filter for sludge/ plugging by pass valve in filter housing.

[Phil Kelly]

So I check the oil pressure relief valve and it's not stuck. Oil filter is new and there is no sludge. For the new gauge, it has a small nylon hose hooked up directly to the block. I've been told that the timming may have something to do with the low oil pressure, but I don't think it's true.

[lepic56]

so did you find anything new on the low oil pressure ???