Low oil pressure

[gzig5]

Brought the car home from storage today and as I pulled into the subdivision the oil pressure light came on.  Verified 5psi on the analog gage and shut it off and coasted most of the way home.  Had to fire up to get in the garage and pressure moved around between 8 and 20 psi.  Shut it off and went back to work.  Came home and it would start out at 20 and then drop and hang at 10 psi at 1000rpm idle.

I know nothing of the history or condition of this 71 340.  I have less than 100 miles on it since I got it running last year.  Fresh 10W-30 Penzoil high milage.   Normally it would have 40-50 psi at cold startup.  20 at hot idle and 40psi+ at 2500 rpm on the road.  Saw same today when I started out on the 15 mile drive home and all was good until the end.

Looking for suggestions on where to start and an order of steps.  I have a new Kevko pan I was planning to put on later, but I can move that job forward.   I'm familiar with the oil system and it is pretty simple.  I know there is a bypass spring in the pump, but I don't know if this is a failure mode common with that. 

[gzig5]

Will the oil  pan come out without jacking the motor up or dropping half the suspension?

[1 Wild R/T]

Small block pans come out fairly easy...  Relief valve on the pump is a common failure.... First try a new oil filter...

[Bpret]

I agree try new filter first. Get a good filter ie wix or Napa gold.

[Brads70]

   on replacing the oil filter especially if it's a fram.

[gzig5]

 

  on replacing the oil filter especially if it's a fram.

Easy place to start.

It's got no time on it but is one of the orange ones. Got a wix on the shelf

[gzig5]

Got the filter off and was just going to slap the Wix on but the oil is a bit darker than I'd expected after so few miles.  So, I am going to throw some more fresh 10w-30 in with the new filter tomorrow after I get some more oil.  I only have 10w-60 and 20W-50 on hand and I don't want to change more than one thing at a time if I can help it.  I'm sure the 20W-50 VR1 will run higher pressure out of the box.

Thankfully the oil doesn't reek of gasoline like it did last fall when I changed it and the filter, but there could be a bit in there.  That was the product of a totally hosed up carb which was rebuilt and seems to be running better.  But, I have suspicions that the fuel pump is putting out a bit too much pressure (6.5-7.5psi)and could be overriding the float seat.  I've got a regulator ready to go in to correct that and a new Edelbrock AVS2 so I'm starting at ground zero on the fueling system.

[gzig5]

  on replacing the oil filter especially if it's a fram.

Easy place to start.

It's got no time on it but is one of the orange ones. Got a wix on the shelf

I've got to admit, I'll be very surprised if it is the filter.  I've used Fram filters for thirty years.  Can't remember ever buying anything else for my Mopars/Jeeps, and I never had a problem that I was aware of.  I also have a bit of a personal stake in the Fram filter empire that kept me buying that brand.  I do industrial automation and motion control and back when I was in the field, I made a service call on the Fram factory near Dayton, OH.  The machine that pleats the filter media was acting up so I gave the servo system a bit of tuning for the loop gains and tweaked a few other processes that they wanted to optimize.  Kind a neat process they used to put them together and test them.  Very automated.   Now, before anyone jumps to any "collusion" theories, I'm sure I had nothing to do with the problems folks may have had with Fram filters.    I hope.

[dodj]

Relief valve on the pump is a common failure

This gets my vote....

[Chryco Psycho]

Fram Used to be OK but as soon as Honeywell bought it they became garbage , I have not used one in 20 years now ,
Wix is good , I would run 10-40 oil while you are at it this could easily be the whole problem !
second choice would be the relief valve sticking or debris in it .
Yes the oil pan will come out but you do have to remove at least 1 side of the center link & swing it out if the way , often you need to rotate the crank to get the counter weight out of the way too

[Brads70]

  on replacing the oil filter especially if it's a fram.

Easy place to start.

It's got no time on it but is one of the orange ones. Got a wix on the shelf

I've got to admit, I'll be very surprised if it is the filter.  I've used Fram filters for thirty years.  Can't remember ever buying anything else for my Mopars/Jeeps, and I never had a problem that I was aware of.  I also have a bit of a personal stake in the Fram filter empire that kept me buying that brand.  I do industrial automation and motion control and back when I was in the field, I made a service call on the Fram factory near Dayton, OH.  The machine that pleats the filter media was acting up so I gave the servo system a bit of tuning for the loop gains and tweaked a few other processes that they wanted to optimize.  Kind a neat process they used to put them together and test them.  Very automated.   Now, before anyone jumps to any "collusion" theories, I'm sure I had nothing to do with the problems folks may have had with Fram filters.    I hope.

I used to work at a local stock car track for 25 years , and at least once a year  I'd find someone       ( usually newbies) loading the car up after practice thinking engine had an issue as it had no oil pressure. I'd look down and if it had that familiar orange oil filter I would say to go to the parts truck and get a Wix oil filter. When I could convince them to try changing it not always but often oil pressure returned.
In the original posters case I figured it's worth a try/cheap to try first. Usually in my experience with the filter issue the engine has no oil pressure.  This one has low oil pressure? 

[Chryco Psycho]

sounds like you had good oil pressure when you parked it in the fall so the oil filter could have disintegrated over the winter causing the issue
I doubt anything serious is wrong if you had good pressure last time it ran

[gzig5]

This one has low oil pressure? 

Yup, it's got some. Kind of acts unsure of itself, bouncing around a bit.  Rev the engine slightly and it will climb just a bit and go back to about 12psi.  I only ran it a little to understand how it is behaving.  Waited until it was completely cool to see if the pressure came up again, which it did not.

I cut the filter open last night and there wasn't anything shiny or metallic in it, just some "dirt" in the pleats and some small 1/16"-ish chunks in the bottom.  Looks like it was doing what it should.  I think I will try some 10w-40.  The 30wt went in because it was on sale.  I'm sure the clearances in this engine can sustain 40wt or higher. 

Not looking forward to messing with the center link, I just replaced all those parts last fall and don't want to tear the boots.  Hopefully  they will pop off with the HF tool and a BFH.  I really do want to get the Kevco pan on so I don't have to worry about the pickup uncovering, like it has been until I over filled it a bit.  Something is not quite right in there, maybe the pickup is loose.  Considering all the other stuff I've uncovered on the car, I won't be too surprised.  I just hope it isn't total rebuild time yet.  I'm planning on a good build but the other stuff needs to get done first.

Sorry for rambling.  My wife and kids have no idea what I'm talking about so this is my place to vent a little.  Don't have a puppy to pet....

[1 Wild R/T]

Usually you can just unbolt the idler arm from the K member & swivel the drag link down & back enough without separating any of the tapered attachment points....

[Strawdawg]

Did you check the bypass valve to see if it might be stuck open slightly?