Oil Pump Problem?

40ford

40ford

Well-known member
I have a 1940 with a 59AB engine.I have noticed on two different occasions that when I stop and start off again that my oil pressure does not seem to come up any.It stays at about 15 or so for a minute and then it goes up to normal.I notice the engine seems to be a little noisy like a small rattle in it when the pressure is low.Is my oil pump going out or something else.It has me real concerned because I don't want to ruin a good running flathead!
 
Here's a thread that might be helpful: http://www.fordbarn.com/forum/showthread.php?t=68047&highlight=Oil+Pressure

Two things to keep in mind:

1. Your dashboard gauge might not be accurate. Mine wasn't. Read that thread to see how I tested it to find out and how I solved the problem (replaced defective sender).

2. The flathead engines don't need oil pressure to lubricate them, they only need oil flow. Any pressure at all indictes that the oil is flowing everywhere that it should be so not to worry too much about low oil pressure.
 
Old Henry said:
Here's a thread that might be helpful: http://www.fordbarn.com/forum/showthread.php?t=68047&highlight=Oil+Pressure

Two things to keep in mind:

1. Your dashboard gauge might not be accurate. Mine wasn't. Read that thread to see how I tested it to find out and how I solved the problem (replaced defective sender).

2. The flathead engines don't need oil pressure to lubricate them, they only need oil flow. Any pressure at all indictes that the oil is flowing everywhere that it should be so not to worry too much about low oil pressure.
Click to expand...

I like it when you say that,it makes me worry less ,my 41 is low.
 
40ford said:
I have a 1940 with a 59AB engine.I have noticed on two different occasions that when I stop and start off again that my oil pressure does not seem to come up any.It stays at about 15 or so for a minute and then it goes up to normal.I notice the engine seems to be a little noisy like a small rattle in it when the pressure is low.Is my oil pump going out or something else.It has me real concerned because I don't want to ruin a good running flathead!
Click to expand...
I wish i had 15# at hot idle,mine drops to 3-4# but goes up when going again. ken ct.lol:)
 
Sounds to me like the bypass valve on the oil pump leaks. I have seen this before. G.M.
 
The engine in my pickup shows the same phenomena. The pressure comes down after warm up. I did shim the spring by .070" on the valley bypass. Right after I did it was holding 40-45 PSI on the road and 10-15PSI at idle. I think I may need to replace the spring since the longer this engine runs the lower the pressure is. After a 2 to 3 hour run the pressure dropped to 20 -25PSI on the road and 5-10PSI idle.
Here is a link to more info. http://www.fordbarn.com/forum/showthread.php?t=68702
 
Old Henry said:
Here's a thread that might be helpful: http://www.fordbarn.com/forum/showthread.php?t=68047&highlight=Oil+Pressure

Two things to keep in mind:

1. Your dashboard gauge might not be accurate. Mine wasn't. Read that thread to see how I tested it to find out and how I solved the problem (replaced defective sender).

2. The flathead engines don't need oil pressure to lubricate them, they only need oil flow. Any pressure at all indictes that the oil is flowing everywhere that it should be so not to worry too much about low oil pressure.
Click to expand...
so 3-4 lbs. is ok? i sure hope so. ive got 8BA THAT RUNS GOOD BUT WITH MY GAUGE SHOWING 3-4 LBS AT IDLE, I SURE WAS NOT TO HAPPY.ITS BEEN ABOUT 36 YRS SINCE I LAST HAD A FLATHEAD V8.SO IM STILL NEW TO THIS GAME.LOL.IF THAT IS CORRECT THEN IM FAR BETTER OFF THAN I AT FIRST THOUGHT.
 
The standard for oil pressure is 10 lb for every 1000 rpm. I have a fresh flathead with 12 to 14 lbs hot at idle and 40lbs at 60mph. The pressure changes as the oil gets hotter example: on the freeway at a constant 60mph in hot weather the pressure is around 30 to 35 lbs. if I stop for gas and take a little break the pressure goes back up to 40 to 45 lbs and as soon as I go a few miles it's back to 30 to 35 lbs. My engine builder doesn't like to have to much oil pressure because it creates heat and and is of no value to prolonged bearing life. The above description of my engine is the same now with 20,000 as when new. If you have around 5lbs at idle and 20 lbs at highway speed your engine will probably outlast you unless you just got your license.
Don
 
37 Your oil pressure sounds about perfect but is no where near what you describe a "standard" oil pressure. How does normal oil pressure cause heat ??? More oil flowing through the bearing surfaces is going to take heat out with it. The oil spashing around is going to get cooled by air as it splashes, the sides and bottom of the pan being cooled from outside air and the block that is water cooled. Your 5 or so lbs dropin oil pressure when real hot in my opinion is the oil thinning from heat. Try a differant weight or type of oil. After over 110,000 miles on Castrol 22/50 on a 100 degree day driving a straight 600 miles I only see a few lbs drop if any, is so minimal I don't even notice it. I don't think you want 10/anything in these stock engines. G.M.
 
Hi George, I don't want to get into a lengthily discussion about this subject but the more you try to force the oil by the bearings at high pressure the more friction you create. You are right about more oil passing thru the bearings keeps the bearings cool and the the more flow not the more pressure does exactly that. That is why we use high volume pumps as opposed to high pressure pumps. That"s just my opinion and I can't back it up with scientific reason. I use 20w50 oil.
Regards, Don
 
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