Need help 427 low oil pressure ?
 

Hello All,

I am hoping you guys could guide me with your knownledge and experience.

I have a 427 side oiler that has low oil pressure. I have reading the threads and I see that most of the 427 with HV oil pumps or even standard pumps are running between 60 - 80 psi at idle. I have also come across a thread that this person is running 25 psi.

In my setup I am running 2 oil filters and a armondo oil pan. I am not sure of the oil pump if it is a HV or not. My current pressure reading is 10 - 15 at idle running 10- w30 oil with Motorcraft oil filter. I know this is not normal which is why am seeking advice.

I plan on changing out my oil pump and would like to find out what springs and relief valves I should check or replace. I am running a solid lifter roller cam to keep in mind.

Is there anything else I should check before pulling the pan?

Thanks:CRY: b

Check the plumbing to the oil filters.

Many times I have read where the flow was backwards through the filters - an easy mistake to make by an expert.

Are the lines and fittings big enough?

Short elbow kill flow.

Many oil pressure problems are in the external plumbing.

Try putting a T in the line where the oil is comming out of the block and put a gauge on it there. See what the oil pressure is there before planning your next move.

Hi I am using a -12 line to the filters and the feed is coming from the top of the port from the motor. I will post pics if needed.

Do post some pictures of your plumbing if you can Priobe.
10 - 15 psi at idle is not good at all, way too low. If it was my engine I would not run the engine until you get the pressure issue diagnosed. If you are running twin filters you should most certainly be using a high volume oil pump IMHO.
Old dog is dead on with his advice.
Other questions I might ask is are you running restrictor plugs in your heads, what about the condition your valve stem seals, amybe a clogged oil pump pick up? Possibly a loose seal/connection in the pump pick up attachment area, there is a lot to consider.
If your plumbing is correct and you have the HV oil pump in place you might want to consider the settings, or lack thereof, of your oil pressure relief valve at the back of the block as well as the pressure relief/bypass setting in your oil pump. I shimmed out the pressure relief spring in the oil pump to boost pressure and eliminated the engines pressure relief valve all together.
With these modifications, at idle, I am seeing 70 psi. In the upper rpm range the OP is right at 100 psi. Many will say this is too high but I would disagree for many reasons, but thats another thread.
Lets see some photos when you get a chance.

Here are the pics.

The way my system is plumbed is that the top AN fiting is connected to the "OUT" of the oil filter adaptor. The lower AN fitting is connected to the "In" port of the oil filter adaptor. Then I have my gauge port connected to the "top" AN fitting which is the "IN" Port.

So... my thoughts are that the pressure reading that I am getting is after the filters.

Is this correct?
:CRY:

Here is a complet system plumbing shot

What year 427 do you have? There is also a oil pressure relief valve in the block. Common error some guys make is to put the plunger before the spring. This can cause low oil pressure. If your block is a marine casting it might not be machined for the RV. Just another thought besides your plumbing...

G.

FFR428,

I am not sure which way the oil relief valve was installed. I did not install it. My block does have this provison. I hope that I will not have to remove the tranny to find out. Just for referrence are you saying that it should be installed :

Block , plunger, spring, alan plug.

Also, can anyone tell if my plumbing is correct?

Any other suggestions before I remove the oil pan?

What oil pump do you guy recommend? I figure if I am going to pull the pan for the oil pump, I might as well replace it.

Do you guys shim the pump or is it a straight install?

Why not go back to bone stock oil filter ,bypass all the extra plumbing and see what happens before pulling it all apart? East and may help with your diagnosis.Just my .02c

Priobe,

Check out this link: http://www.erareplicas.com/427man/engine/oilpress.htm

Chris

http://www.precisionoilpumps.com/

Precision Oil Pumps
2324 Decatur Avenue
Clovis, CA 93611

Phone: (559) 325-3553
E-mail: pumpbldr@comcast.net

10-15 at idle is not unreasonable. What pressure do you have at higher rpm's? You need at least 10 psi per 1000 rpms. Much higher than will cause excessive wear on the distributor drive gear and add heat.


JGC

Kinda hard to tell from the pictures but, it looks like you have it plumbed incorrectly?. Mine goes to the filter first, then oil cooler, then back to block.
On the block where the oil filter adapter plate bolts up, the top hole in the block goes to the engine and the bottom comes from the oil pump.
Take a look at my pics.

427 S/O,

I do not understand your explanation.

The top hole on the engine block from the motor is that going to the "IN" of the filters?

Also, the bottom hole of the block oil filter adaptor - Does that go to the out of the oil filter relocator


Also for other post I am getting (assuming) 10 -15 on my stewart Warner gauge and with a cheap mechanical gauge. When I drive I only get max 27 -29 psi.

CJ428CJ,

My block is a Side Oiler. I do not think that this hole is located on S/O.

But I could be wrong.

Do you know if Side Oilers have this plug

Priobe,

No, I don't know if side oilers have that plug/hole or not.

Also, many of the above suggestions focus on suggestions like the plumbing might be too small, fittings might be restricting flow, the plumbing to the cooler might be wrong, etc. While all of these things are important, they won't cause low pressure. If I see your picture correctly, you're measuring the oil pressure at the remote adapter right at the block, correct? If that's true, any blocked, undersized or reversed lines after the remote adapter will cause your oil pressure to read too high (but with little or no flow through your engine).

Once you determine that your gauge is accurate, I think there can be only a couple of possible causes. Either 1) your oil pump is not working right (they have a bypass spring in them that could possibly be stuck), 2) the oil pump is starving for oil (because the pickup tube is loose or the gasket is missing causing the pump to suck air or because the pickup is too close to the bottom of your pan) or 3) you have an internal oil leak. An internal oil leak could be caused by a missing internal oil galley plug or it could be caused by excessive rod or main bearing clearances.

What's the history of your motor? Is it an older motor with with some miles on it or is it recently rebuilt? If it's rebuilt, did you do the work or did someone else? How were bearing clearances checked?

Chris

Here is a brief description of my setup:

New rebuilt motor (Engine Builder did work)
Oil line size -12 from oil block side of motor to oil filter ( no oil cooler yet)

Top oil line from block is connected to the "OUT" of the filter adaptor
Bottom oil line from block is connected to "IN" of the filter adaptor

Oil filter Motorcraft
Oil - 10-W30 current 10- 15 idle no more than 30 driving
Oil - Previous- 5- W15 Mobile One Synthetic alittle higher reading 20 -25 idle

Clearance on mains .002 ( that I could recall) measured when motor being built

Oil pump Melling HV

Motor was dyno tested and everything test fine


Here is a pic of the motor before rebuild and it does not look like the Side Oilers have that port

Why not put 20w50 and check that out.Personally I never use very thin oils.

I could try but I am not sure if it would make up the difference in pressure loss.

Do you think it is worth the try?

The spring goes in first, then the valve, then the allen plug last. I don't think your block has the "mystery hole" either. But if you did it would be affected by the adapter plate or later adapter oil passages bleeding into it. That dang hole was on a old 406 block I had also. I like Chanmadd's idea of trying just the stock filter and adapter...and also going to a little heavier oil. I'd document each step one at a time instead of doing a combination of things at once. I would also try the simple things before digging into it.

G.