What oil pressure should the engine run? Mine runs about 5-10 at idle then 20 at 35 mph and tops out at 25 pounds at 55 mph. These measurements are taken by observing the oil pressure gauge on the dash. The engine was rebuilt but I'm not sure how much rebuilding was done; for sure new pistons and rings (no ridge at top of cylinders) plus main and rod bearings. Thanks, Chet 25441
First thing I would do is plumb in a known good gauge so that you can be sure your dash gauge is reading correctly. Plumb it into the same port as the dash unit. I just had a cheapie gauge with a plastic line. I didn't want that plastic line in the cabin so I just used blue tape and taped it to the windshield. I must have looked like an idiot going down the hiway with a gauge taped to the center outside of the wondshield. However it confirmed my other gauge was incorrect.
Jeff
In most cases, the factory gauges, be it oil pressure, or water temperature are just a guide, that there is either pressure, or temperature in there.
Bruce. >:D
Chet,
Actual low oil pressure, especially at idle, will probably give you valve/lifter noise when the engine is hot (based on my past experience). If your oil pressure is low then you would most likely be hearing valve tapping when the engine gets hotter. My newly overhauled 346 displays 25 psi at idle and maybe 30 psi above on the gauge. Hope this helps, Ken Z ;)
Thank you for the replies. The engine runs very smooth at idle with no noise so I must guess it is being oiled. Chet 25441
You can also try cleaning the contact on the sending unit. Corrosion there could lead to a lower than normal reading.
Jeff
Quote from: Jeff Rose CLC #28373 on August 01, 2017, 12:38:30 PM
You can also try cleaning the contact on the sending unit. Corrosion there could lead to a lower than normal reading.
Jeff
Not electric on a 346 Jeff. It's an oil pipe.
Woops.
Your oil pressure numbers are very normal. Multi-grade oils lubricate well, but they don't register on a fully functional oil gauge much above 10 pounds when the engine is hot and at idle. CHeck your car's manual. Some Cadillac model years recommend 30 weight oil in the summer rather than multi viscosity oil. Single grade (ie 30 weight) will push your gauge farther up the scale, but may not be what is recommended by the design engineers for your car's motor. You'll note in your car's manual, a brief "advisory" that states when your car is at idle and hot, that the "idiot oil light" may briefly illuminate... that sensor is nothing more than a pressure switch that connects to the idiot light and illuminates it at pressures less than 7 pounds... not to worry--- James
Quote from: James Landi on August 08, 2017, 09:47:41 PM
Your oil pressure numbers are very normal. Multi-grade oils lubricate well, but they don't register on a fully functional oil gauge much above 10 pounds when the engine is hot and at idle. CHeck your car's manual. Some Cadillac model years recommend 30 weight oil in the summer rather than multi viscosity oil. Single grade (ie 30 weight) will push your gauge farther up the scale, but may not be what is recommended by the design engineers for your car's motor. You'll note in your car's manual, a brief "advisory" that states when your car is at idle and hot, that the "idiot oil light" may briefly illuminate... that sensor is nothing more than a pressure switch that connects to the idiot light and illuminates it at pressures less than 7 pounds... not to worry--- James
James,
You are Correct...I run 10W-30 in my Flathead, and those numbers are pretty much on the money. If you use a modern style gauge that has the readings in increments, you'll get a higher, more accurate reading than the old school gauge.
Bobby
my 41 346 was rebuilt new everything. it runs at 30 . when really hot on the hottest day 28-30.
Thanks for all the input; I will put the issue to rest believing the numbers are normal. Chet 25441