304 oil pressure drop

[LutzCoyote]

Good Day,
I have a 72 Scout II and the issue is the oil pressure gauge drops from its normal 40ish to zero once the engine is up to normal operating temperature. I haven't noticed any knocking or excessive engine rattle.

Some basic information, I currently run 5w/30 high mileage oil, Wix oil filter, 7 quarts with a filter change and use ISSPRO guages.

I'm asking those of you smarter than myself if you think it's evidence of an oil pump going bad, oil pickup getting clogged up, lifter issue, or simply the sending unit needing replacement

 

[int77345]

i would start with the sending unit, my oil pressure gauge does that also.

 

[ihpartsjeff]

Unless the engine is a fresh rebuild I would recommend 20w-50 or at least 15w-40. 5w-30 is pretty low on viscosity for an IH engine. But yes verify that the gauge you are running is accurate by testing with a known good mechanical gauge hooked direct to the engines oil port that you are using for the current Isspro gauge.

 

[LutzCoyote]

i would start with the sending unit, my oil pressure gauge does that also.

Unless the engine is a fresh rebuild I would recommend 20w-50 or at least 15w-40. 5w-30 is pretty low on viscosity for an IH engine. But yes verify that the gauge you are running is accurate by testing with a known good mechanical gauge hooked direct to the engines oil port that you are using for the current Isspro gauge.

Unless the engine is a fresh rebuild I would recommend 20w-50 or at least 15w-40. 5w-30 is pretty low on viscosity for an IH engine. But yes verify that the gauge you are running is accurate by testing with a known good mechanical gauge hooked direct to the engines oil port that you are using for the current Isspro gauge.

Thanks guys for the responses, I'm going to replace the sending unit and the oil to begin with to see if that fixes the issue.

IhpartsJeff, is there a particular brand of 20w50 you've had success in using?

 

[int77345]

i have used this for years. i believe its the best
https://www.ihpartsamerica.com/store/SWEPCO-ENGOIL-306.html

 

[Dealbreaker74]

Definitely get a manual pressure gauge. You won't need to install it permanently. You just need to see what the hot running pressure actually is. My '74/345 shows next to nothing at the bottom of an off ramp at op-temp...But the mechanical gauge shows 10 lbs at 600 RPM at the stop light, so I know I am safe regardless of what the stock one reads. The Swepco oil is a solid choice too. But any 20w-50 will hold up better at temp than the thinner stuff.