1961 Falcon - long time to build oil pressure after sitting.

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Jan 2, 2017
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Recently posted on a recently acquired Falcon (got the fuel leak sorted out). Now there's a new potential issue. A few weeks ago I hadn't driven it in a few days. When it started, the oil pressure light stayed on for probably a minute. I checked the sending unit. It was old, and leaking a bit, so I replaced it. However, a few days ago, again after not driving for over 24 hours, it did it again.

Once the light goes off, it stays off...at idle, under throttle, etc. Additionally, if you park and then start the car shortly after, it goes off quickly. Even after sitting hours, it might stay on a max of a couple of seconds. I thought it might be some sort of electrical issue, but today I went and bought an oil pressure tester from Harbor Freight. The Falcon hadn't been driven for over a day, so I tested it. Upon start-up the mechanical gauge registered zero oil pressure for close to a minute. It then promptly shot up to 42 PSI at idle (bouncing slightly, but the idle is also a bit uneven, pulling the choke evens the idle and reading out). Revving the engine brought the reading up to 51 PSI (not sure of the exact RPMs, but less than highway speed). With my foot on the accelerator, the reading doesn't bounce around.

Oil was changed by me several weeks ago. Filter is a Motorcraft unit. Oil weight is 10w-40 with a minor amount of Lucas zinc additive. Oil level is fine.

Any thoughts on what to check next?
 
Joined
Aug 20, 2003
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NE,Ohio
oil pump? oil pickup?

almost sounds like the oil pump loses its prime for whatever reason.

disclaimer: not an expert.
 
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Feb 6, 2010
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These weren't the best cars made when new. I can only imagine what 60 years has done to it. The first car I remember my dad owning was a '61 Falcon. He traded it off I think in '69. It had 77,777.7 miles on it when he pulled it on the lot to trade it off. He had already rebuilt it once and it was needing it again. I had an '88 Escort several years ago that got slow to build pressure and the pressure dropped to near 0 at idle according to the aftermarket mechanical gauge I'd installed. I pulled the oil pan off and cleaned the pick up tube and everything went back to normal. I'd start by cleaning the pick up screen. I suspect the oil is cold/thicker on that first start of the day and is having trouble getting past an obstruction in the screen. Subsequent starts later the same day the oil hasn't fully cooled thus it's thinner and flows easier.
 

ArtDecoWorld

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Jan 2, 2017
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Losing prime seems like that could cause this.
I'm definitely going to drop the oil pan and see what the pick-up screen looks like.
From the shop manual it definitely seems like the oil pump is easy to access and change if need be.

If anyone needs to view a shop manual for a 60-65 Falcon, then this site has them. It sure is nice when a google search works out that way.
 
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Jun 28, 2012
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Check the pickup screen being plugged with goo. Should be pretty easy to pop the pan off. Might have to drop some of the steering linkage off.
 
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Either the pump can’t build pressure or worn bearings let’s too much oil flow out. These are possible.

pump could be shot - or the bypass valve stuck partially open. It just a spring pushing a checkball against a hole. This would also allow loss of prime. I’m leaning hard towards this one.

wont help if the pickup screen is clogged.

a new pump shouldn’t be more than $40. I’d just go ahead and replace it if you’re going to go through the trouble to replace the pan. if it’s like older chevys with the pinned axle driving it from the distributor (i was more familiar with the older chevys), make sure you understand what you are looking at before jamming the pump back up in there.

neat classic btw!

good luck!
 

ArtDecoWorld

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Ok, I got the oil pan off. Here are photos of the pickup screen and some other shots of the pump.
The oil pan had a few pieces of metal in it. Penny is shown for comparison. The small disc was in the oil. The four larger chunks are metal. Some of the smaller pieces are gasket material as it took some slicing and prying to get the pan loose. I have no idea when the pan was last off, but it was stuck pretty good.
 

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Joined
Jun 28, 2012
Messages
2,981
Location
High Tax Illinois
Well the screen ain't plugged. Take the oil pump off and take it apart to see if it's worn or the bypass has crud in it. You could pop a main cap off and check the bearing or bearings depending on what you find. Keep us posted!!! Neat to see a old engine insides.
 
Joined
Jul 3, 2005
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NY
You got the pan down I'd be inclined to look at the bearings, and replace if needed along with the oil pump. The car is 60 years old.
 
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