The Stovebolt Site Forums The Shop Area Engine Shop oil pressure

My motors manual says max oil pressure for a 1955 235 is 35 psi. On a cold start up I have a 30 psi reading, and after fully being warmed up have 5 psi at idle and between 10 to 20 psi depending on engine speed. The engine is rebuilt and a new oil pump was installed. Are these oil pressure readings correc or should I have more pressure.

thanks
John Gott

That's low. Are you using your original gauge? You might want buy an after market oil pressure gauge just to check it. I had an '75 Dodge 360 that went down to 5 psi at hot idle before I sold it.

I have tried 3 differant mechanical gauges with the same readings on all three.

My 49 216 carrys 10+ at idle. what oil vis are you using?

I am using Valvoline 30w. I will try try 40W (Wolfshead brand) tommorow..........

I don't think that you want to use heavier oil to make the pressure reading look good, that is a mistake. If the pressure is on the low side, there must be a reason.

I agree, the specs for my 49 says 20 weight so I would be careful with the heaver ones, I was thinking you might have been using a multiweight.

Unless bearing clearances were set way to loose I would say the oil pump relief valve is stuck open.

Hello All;
thanks for the replys, so her is an update:
I took the lifter cover off and checked the oil line that goes to the head and found a kink in the line, so I go to the hardware store to get some 3/16" line, and that was a no go, so off to NAPA (should have gone there first.
Anyways, I took a shaft from a spare distributor and attached it to my drill to prime the engine, VIOLA, instant 35 psi, and with the drill slowly turning I had 20 psi (55 degrere day, oil cold and using 40W) with the oil line disconnected.
So my question is, why do I have higher oil pressure using a drill, with the engine not running?
I would think the oil pump would prime itself with the engine running.......

i am not an expert but i believe that kink you were referring to is suppose to me there. i read that somewhere in this forum once upon a time. i have a 235 out of a 62 chevy and i have a kink in the line but then i also struggle with any oil pressure at all at idle.

The oil thins out within about a minute of startup, so comparing the maximum pressure with your drill is tricky. On my 216, turning the oil pump with the drill makes the drill work pretty hard. If you don't experience that with the drill something is definitely wrong .

thanks for all the replys.

Anyways what weight oil should I use, 30 HD, 10w30, 40hd, 20w-50.............
And what should my oil pressure be at idle for a '55 235. Idle being 550 -600 rpm's

Thanks
john Gott :rolleyes:

5 psi at idle is enough,but as soon as the engine speed is increased,the pressure should go up to at least 25 psi when warm.These engines will run for a long time with low oil pressure if ya don't push hard.
A 235/261 with a good oil pump and proper bearing clearances will have when hot,30-35 psi at idle and 40-45 psi going down the road.
If your engine has such low oil pressure,it either isn't rebuilt or was a quicky job or the machinist booted the clearances.Use a heavy enough oil to maintain a reasonable oil psi when hot.