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Erratic oil pressure

Avalanche

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Location
Massachusetts
Has anyone had this issue?
It's a 440, but the oil pressure is about 60psi. Only weird thing is the pressure gauge bounces back and fourth at a high rate. Trying to find out what can cause this.
Thanks
 
Only thing comes to mind. It's not getting constant pressure. Air bubbles. Purge gauge line might help.

A high-rate bouncing oil pressure gauge typically indicates one of three critical issues: system pulsation from a failing dampener or relief valve oscillation, air contamination (aeration) due to low oil levels or suction-side leaks. Low oil level in oil pan.
 
A little more info would help, like pressure at idle, max pressure, hot pressure, cold pressure. And when does it do it? All the time? At idle? At road speed? Hot? cold?
 
A little more info would help, like pressure at idle, max pressure, hot pressure, cold pressure. And when does it do it? All the time? At idle? At road speed? Hot? cold?
I was hopeful that someone would have had the same issue and had a fix.
Sounds like it can be a bunch of things.
Idle pressure cold is about 60, I would assume it goes down a bit when warm. Car is at mechanics shop right now.

I like to thank everyone who answered, at least I have a list to get through.
 
It's most likely the pressure spring, but you really need to take the pump off to deal with it. And at that point, I'm putting a new pump on. $120 for a Melling M63 is better that a new 440!
A new pump isn't the worst that can happen. If it's a pump, it's manageable.
Thank you
 
60 at idle is WAY TOO MUCH. 60 is plenty at hot max. Do you know which pump is on the engine? That pressure would indicate either a hi volume or hi pressure pump. About the only other thing I can think of is a stuck by pass spring. There used to be a tag on the pump if it were either of the hipo ones. If it is the by pass spring, that can be dealt with by simply freeing or replacing the spring. If a hi volume is on there, a change to the standard pump seems prudent.

I usually run the hi volume pump and haven't seen your problem with them. So, I would start with checking out the by pass spring as others have suggested.

15 to 20 pounds of hot idle oil pressure is plenty and again, 60 is plenty at hot max. Any more than that just puts unnecessary wear on the oil pump drive shaft and it's bushing as well as wasting a bit of horsepower. Cold will be somewhat higher, but hot pressure is where the engine spends most of it's time, so it's what we concentrate on.

And by the way, what weight oil are you running? That will also have an impact on your issue. I always used to run a heavy oil. But anymore, with tighter engine tolerances, I don't run 20w50 like I used to. Since I have a preluber, I don't need a multi grade oil. I run Valvoline VR1 30 weight. Many engines would be good with VR1 10w30 as long as their pressure is within the above range. I have just over 20 pounds hot idle and about 65 pounds hot max with a hi volume pump in the Hemi. Been that way for several years now.
 
60 at idle is WAY TOO MUCH. 60 is plenty at hot max. Do you know which pump is on the engine? That pressure would indicate either a hi volume or hi pressure pump. About the only other thing I can think of is a stuck by pass spring. There used to be a tag on the pump if it were either of the hipo ones. If it is the by pass spring, that can be dealt with by simply freeing or replacing the spring. If a hi volume is on there, a change to the standard pump seems prudent.

I usually run the hi volume pump and haven't seen your problem with them. So, I would start with checking out the by pass spring as others have suggested.

15 to 20 pounds of hot idle oil pressure is plenty and again, 60 is plenty at hot max. Any more than that just puts unnecessary wear on the oil pump drive shaft and it's bushing as well as wasting a bit of horsepower. Cold will be somewhat higher, but hot pressure is where the engine spends most of it's time, so it's what we concentrate on.

And by the way, what weight oil are you running? That will also have an impact on your issue. I always used to run a heavy oil. But anymore, with tighter engine tolerances, I don't run 20w50 like I used to. Since I have a preluber, I don't need a multi grade oil. I run Valvoline VR1 30 weight. Many engines would be good with VR1 10w30 as long as their pressure is within the above range. I have just over 20 pounds hot idle and about 65 pounds hot max with a hi volume pump in the Hemi. Been that way for several years now.
I also use a Accusump as a pre-luber as well. I have the exact same oil pressure readings with my Hemi also for several years now.
 
60 at idle is WAY TOO MUCH. 60 is plenty at hot max. Do you know which pump is on the engine? That pressure would indicate either a hi volume or hi pressure pump. About the only other thing I can think of is a stuck by pass spring. There used to be a tag on the pump if it were either of the hipo ones. If it is the by pass spring, that can be dealt with by simply freeing or replacing the spring. If a hi volume is on there, a change to the standard pump seems prudent.

I usually run the hi volume pump and haven't seen your problem with them. So, I would start with checking out the by pass spring as others have suggested.

15 to 20 pounds of hot idle oil pressure is plenty and again, 60 is plenty at hot max. Any more than that just puts unnecessary wear on the oil pump drive shaft and it's bushing as well as wasting a bit of horsepower. Cold will be somewhat higher, but hot pressure is where the engine spends most of it's time, so it's what we concentrate on.

And by the way, what weight oil are you running? That will also have an impact on your issue. I always used to run a heavy oil. But anymore, with tighter engine tolerances, I don't run 20w50 like I used to. Since I have a preluber, I don't need a multi grade oil. I run Valvoline VR1 30 weight. Many engines would be good with VR1 10w30 as long as their pressure is within the above range. I have just over 20 pounds hot idle and about 65 pounds hot max with a hi volume pump in the Hemi. Been that way for several years now.
I don't know what pump is in the car. I'm going to change out the spring, since it can be done with the pump attached to the engine. Just need to lift the engine up a bit to get at it. I'm running 10w30 oil.
I don't know what the oil pressure is when warmed up, but will look at that when I get a chance.
Hopefully the changing of the spring fixes the problem.
Thanks for the help.
 
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