440 only shows 25 lbs oil pressure at throttle and 5lbs while idling-After rebuild

[minnesota guy]

I have built 15 motors and never an oil pressure problem. Just finished rebuilding a 44 in my 71 Cuda that bent a rod this summer in #3 cylinder, and bent the cast crank. 6 pack pistons....stock rods..just took engine out and didn't do any addt machine work or bring block to machine shop...

All back together, and used a 440 steel crank I had in a box of spare cranks. Standard size. I did some polishing of crank with over 400 grit to take off the rust.

All fitted nice and crank spun nice. Did not feel any tight spots...I didn't check clearances though...Bearnings were standard as well... No mains were of any different sizing. Had it all running with a 528 solid cam. Just didn't seem like it was pumping oil after looking in rockers, had a "feeling" put gauge up to it and 25 lbs pressure when revving it.....near 0 at idle. 10w -30 oil...synthetic. I put on a different oil pump--my dad gave me--new high volume--same results. Not the pump. I looked at both pumps anyway and they had no issues.

Started tearing it down while still in the car....It has all 4 core plugs---Not missing the 2 at timing chain--as I went there first.

I then pulled the cam shaft and lifters last night--Mopar lifters that came with 528 Mopar Perf cam...Don't see any issues there....

Appears I need to pull the block and get to the crank---Crank still spins when I put the crank damper bolt on the crank--and turn it with ratchet...

cam bearings--although cams have always been a little tight in this block--the holes for cam bearings are not blocked.

What if a main bearing was installed "upside down" with hole in bearing now at the bottom--Not sure this is it...I have not done this error before--

--just trying to rule things out........I tried this oil gauge on my other working 440 in my 87 Dodge 4x4--and it immediately went to 75lbs while cranking--so my oil gauge is working.....for test purposes.

Trying to find something w/o having to pull a fresh motor and tear it down..

 

[69a100]

All back together, and used a 440 steel crank I had in a box of spare cranks. Standard size. I did some polishing of crank with over 400 grit to take off the rust.

All fitted nice and crank spun nice. Did not feel any tight spots...I didn't check clearances though..

Why didn't you check tolerances? You NEVER EVER assume anything! Remind me not to have you work on any of my stuff

 

[WP29440SE]

Loose clearances or wrong bearings would be my guess

 

[Homstead]

Why didn't you check tolerances? You NEVER EVER assume anything! Remind me not to have you work on any of my stuff

Agreed, You should at least plastigage the crank if you don't have any micrometers. I`m betting your problem is bearing clearances. Let us know what you find.....

 

[Seventy]

The motor had pressure before? where did you get the crank? I am going to say its your crank. I heard a story of a gentleman with no op in a fresh 440 turned out the crank was under a bit and they used std bearings, pulled the crank, turned it 10, used 10 bearings, op was fine..

 

[minnesota guy]

It was a crank I had pulled from a running motor years ago. It was standard. (I at least measured the mail journals -they were standard and all the same--I just didn't measure bearning clearances--tough crowd!) The Main bearnings were standard as well. It had the typical feel of a crank in its bearings. Rotation but minimal if any drag. My stuff, my motor so I felt no need to plasty gauge. (which I do if I send things out) I was looking for anything else. Obvious I will be tearing it down.

 

[Hemirunner]

I fixed a guy's small block that had this issue. He had standard rod bearings on a .010 under ground crank.

 

[Funship32]

Agreed, You should at least plastigage the crank if you don't have any micrometers. I`m betting your problem is bearing clearances. Let us know what you find.....

X2. Plastigage at the very least. Probably loose main bearing tolerances would be my guess.

 

[dvw]

I highly doubt that excess bearing clearance at the crank is causing your problem if the crank really is standard. I've run .004"+ and still had more pressure than you have. Cracked, loose, or restricted oil pickup? Inaccurate gauge Is there oil going to the top? How does it sound?
Doug

 

[minnesota guy]

Gauge was tried on my other 440 motor after this one and while cranking it gave 75lbs....So gauge gud. No noises. Oil did get to the top....I will get it out soon in next couple days. Just get my son to help me get hood off again. ( I used to muscles this all alone up until few years ago when I was younger and kids were too small to help--Now have luxury of doing it with 2 people)
Will report findings.

 

[Yatzee]

Here is a snapshot of your oiling system so you can get a better understanding of the flow pattern for the oil.

Using this diagram I suppose the first thing to do would be to make sure the oil pump is actually supplying pressure. Don't discount a problem at the pickup as you may either be sucking air where the pickup tube threads into the block or the pickup is not priming well. If you assembled the engine yourself, you may have to double check for plugs properly inserted, rocker rods upside down or plugged galleries. Don't discount main bearing clearances but you should still be able to generate decent pressure regardless.

 

[383man]

My buddy had the same problem with his 340 that a machine shop did some of the build and he finished it. What I found on his smallblock was the machine shop left the oil galley plug inside the block out that is under the dist and is for one of the lifter galleys. I took his oil pan off and then put oil in a pan and put it up in the oil pump sump and spun the oil pump with a drill and I could see right away where all the oil was pouring out the galley plug left out. Course its inside the block so that was the only way I could find it. Not saying its your problem but thought you might want to know about it. Ron

 

[Kern Dog]

Two times I had this problem:
350 Chevy. My second engine rebuild at the time. The shop gave me a .020 under crank with .010 bearings. I took them at their word and didn't plastigage anything. Engine rattled right away and wore the bearings to copper in 40 miles. I had to pull the engine for a crank swap and rod resizing.
440 Dodge. The threaded plug near the fuel pump pushrod area and behind the timing chain was missing. I never knew it was there because the machine shop removed it during the hot tank wash! Hard to know what is missing when YOU are not the guy that removed it.

Try this: see if you can easily "rock" the crank back and forth...maybe with a breaker bar & socket on the dampner. If it rocks easily, there is excessive clearance at the bearings.

 

[minnesota guy]

The crank is the problem. I did some plasti gauge testing. The 003--006 wouldn't crush on the first main....The others were under somewhat as well. Polished too much. It was a spare crank I had of a collection of spares in my pole barn. 20-25 year collection of some of your "spares" and one tends to forget what you have or remember it differently.

Anyway--I took Another crank from the box....I range from .003--.005 main clearances with plastigauge so still a little loose...Just will need to go and get crank ground.

 

[lewtot184]

".005"....still a little loose"....? okie doke.

 

[72Fourspeed]

Well,it ought to rev freely.

 

[super-bee_ski]

why didn't you check tolerances? You never ever assume anything! Remind me not to have you work on any of my stuff

Oops, that takes "Balls" to do Minnesota guy!
At least its fixable

 

[dvw]

The crank is the problem. I did some plasti gauge testing. The 003--006 wouldn't crush on the first main....The others were under somewhat as well. Polished too much. It was a spare crank I had of a collection of spares in my pole barn. 20-25 year collection of some of your "spares" and one tends to forget what you have or remember it differently.

Anyway--I took Another crank from the box....I range from .003--.005 main clearances with plastigauge so still a little loose...Just will need to go and get crank ground.

Did you measure the cranks? What grit did you use? You'll never polish off .003" in a lifetime even with 400 grit. My bet the cranks are close and the bearing bores are too big.
Doug