The Ford Barn

[email protected] · 09-28-2021, 02:22 PM

I'm a new guy with V-8 Flathead Fords. I have a 1946 Ford 239 cu. in. which I believe is the original engine with 64,000 miles. Upon starting, I have 40 psi oil pressure at idle and approx. 70 psi at road speed measured with a mechanical gauge. I'm running 20w-50 oil and I have installed the .063 restriction in the inlet side of the oil filter. When the oil gets to operating temperature, the pressure drops to 5 psi at road speed and 0 psi at idle. The engine runs great with no smoke and no unusual noise. I plan to eventually drop and clean the pan and install a fresh oil pump. Any thoughts?

alanwoodieman · 09-28-2021, 03:17 PM

oil pressure relief spring is bad

Talkwrench · 09-28-2021, 11:47 PM

The main thing is to see pressure at rpm when HOT, you can go by the 10 lbs per 1000 rpm . It's not uncommon to see almost zero (and that will depend on your gauge) at idle.

FortyNiner · 09-29-2021, 05:44 AM

I wouldn't be too quick with a replacement oil pump. Pull the pan and remove any accumulated crud from it and the oil pickup. Might be everything needed. The oil pump isn't a typical wear item.

Bored&Stroked · 09-29-2021, 02:28 PM

One thing for sure - 5 psi at road speed is not enough . . . so until you fix the issue, I'd not be doing that.

As noted, I would pull the pan first and check/clean it all out . . . and probably think about a new (later) oil pump. You can put an 8BA pump in it with the necessary pickup for the early pan. You can buy the pickup at Speedway - which beats the heck out of having to cut, splice, weld up the later pickup for usage in the early motor.

Pickup: (without the screen - they can supply with the screen).

https://www.speedwaymotors.com/Speed...Tube,4289.html

r_reed · 09-29-2021, 08:24 PM

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Are your readings from an original dash gauge? if so, they tend to be quite inaccurate. you might want to add a modern direct reading gauge (you can put a "t" in the oil line where it enters the oil filter, if you have one). if it reads differently from your dash guage, you can mentally calibrate what 5lbs on dash means. the aux gauge does not have to be readiily visible if you want to maint stock look.

[email protected] · 09-29-2021, 09:00 PM

Readings were taken with a modern direct reading mechanical gauge.

09-28-2021, 02:22 PM	#1
[email protected] Junior Member Join Date: Jul 2021 Posts: 3	low oil pressure I'm a new guy with V-8 Flathead Fords. I have a 1946 Ford 239 cu. in. which I believe is the original engine with 64,000 miles. Upon starting, I have 40 psi oil pressure at idle and approx. 70 psi at road speed measured with a mechanical gauge. I'm running 20w-50 oil and I have installed the .063 restriction in the inlet side of the oil filter. When the oil gets to operating temperature, the pressure drops to 5 psi at road speed and 0 psi at idle. The engine runs great with no smoke and no unusual noise. I plan to eventually drop and clean the pan and install a fresh oil pump. Any thoughts?

09-28-2021, 03:17 PM	#2
alanwoodieman Senior Member Join Date: May 2010 Location: upstate SC Posts: 2,963	Re: low oil pressure oil pressure relief spring is bad

09-28-2021, 11:47 PM	#3
Talkwrench Senior Member Join Date: Aug 2012 Location: Perth, Western Australia Posts: 2,687	Re: low oil pressure The main thing is to see pressure at rpm when HOT, you can go by the 10 lbs per 1000 rpm . It's not uncommon to see almost zero (and that will depend on your gauge) at idle. __________________ *"Came too close to dying to stop living now!"*

09-29-2021, 05:44 AM	#4
FortyNiner Senior Member Join Date: May 2012 Location: u-rah-rah-Wisconsin Posts: 1,136	Re: low oil pressure I wouldn't be too quick with a replacement oil pump. Pull the pan and remove any accumulated crud from it and the oil pickup. Might be everything needed. The oil pump isn't a typical wear item. __________________ 19 and 49 F1 - jes' like Henry II built 1946 Deluxe - as Henry built it

09-29-2021, 02:28 PM	#5
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,064	Re: low oil pressure One thing for sure - 5 psi at road speed is not enough . . . so until you fix the issue, I'd not be doing that. As noted, I would pull the pan first and check/clean it all out . . . and probably think about a new (later) oil pump. You can put an 8BA pump in it with the necessary pickup for the early pan. You can buy the pickup at Speedway - which beats the heck out of having to cut, splice, weld up the later pickup for usage in the early motor. Pickup: (without the screen - they can supply with the screen). https://www.speedwaymotors.com/Speed...Tube,4289.html

09-29-2021, 08:24 PM	#6
r_reed Senior Member Join Date: May 2010 Location: east glenville NY Posts: 158	Re: low oil pressure Sponsored Links (Register now to hide all advertisements) Are your readings from an original dash gauge? if so, they tend to be quite inaccurate. you might want to add a modern direct reading gauge (you can put a "t" in the oil line where it enters the oil filter, if you have one). if it reads differently from your dash guage, you can mentally calibrate what 5lbs on dash means. the aux gauge does not have to be readiily visible if you want to maint stock look. __________________ 1949 F-1 Flatrod II (flat paint, flat motor) Keeping one more flathead alive It smoked, but gave it up 7/26/2013 East Glenville NY

09-29-2021, 09:00 PM	#7
[email protected] Junior Member Join Date: Jul 2021 Posts: 3	Re: low oil pressure Readings were taken with a modern direct reading mechanical gauge.