Hi Gang,
I have a 55 chevy 235 six.. while driving up North this past weekend, my oil pressure was running about 30 lbs. when I came to stop the oil pressure dropped to 10 lbs and sometimes 5 lbs. if I raised the idel slightly it came back up.. Sooooo, could it be the switch or the pump.
I sure hate the thought of pulling the pan..
Thanks
Mike

Oil pressure drop at idle on older 235s is normal and OK.
As long as you get 35 lbs at 2000 rpm the oil pressure is to spec.

Thanks.. I get about 30 steady at speeds above idle.. at idle very low.

Lots of oil.. doesnt smoke. runs good.. just low pressure at idle

Dear Mike;

Is you guage mechanical or electric??

"about 30 lbs" leads me to believe It's below normal, at run speed and idle. :rolleyes:

You need to find out what it "really" is, before we go any further.

How high is it, when you first start it cold??

cold it's 35 lbs. after it warms up driving down the road it runs about 30 lbs.. at idle sometimes its about 10. If I run it for a long time, like a trip,it drops to 5 at idle.

The gauge is mechanical. oil tube running from switch to gauge

M;

Okay; Is this one of those plastic tubes that runs off a "T" fitting, before the electric "oil light switch"??

What weight oil are you running??

Yes, but I used a copper line instead.
I was running 10-40 and the pressure was lower.
I am running 20 -50 and cold its 35
warm 30, idle 5-10.

Note the enigine does not smoke and has plenty of power.

Dear Mike;

Multi-grade oil doesn't work well in the 'older' engines, SAE 30 is much better, for that reason. Some add a pint of STP also.

This works great in mild climates, but may have limitations in Pa. (wintertime) etc.

Copper is best, make sure the line & ALL fittings are clear, first.

If there's no improvement, switch to SAE 30 (4 Qt) & see the difference. If there is, add a pint of STP & the readings will then,, come up to 'normal'.

A 50+ reading is 'normal' when cold for a used engine.

You'll need a 5+ minute "warm-up" in the lower temps.

Happy trails.