Low Oil Pressure Investigation...any tips?

[squidtone]

Hi folks,
The saying goes you can't cheat death and taxes, but maybe they should add "and low oil pressure in a L134".
I've got a mystery L134 in my CJ3A with no numbers. STD pistons, and I fixed the oil jet last summer (to smaller jet size). After the oil jet repair, I still only see 2 or 3 PSI at hot idle (checked with two gauges) and maybe 20 psi when driving in high gear.
This spring, in the last few drives I've taken, the motor has developed a knock that is getting louder and louder. It happens when I'm in third gear, and I give it heavy throttle. I figured I need to park it and find out what's wrong. Since I've never been that far into the engine, today I removed the oil pump and measured all the specs according to the Universal shop manual. It easily meets all specifications. (both rotors, ID and OD, and end gap) I believe the pump is good.
In a fit of despair of not being able to drive the Jeep, I just dropped the pan to see what I can see. Nothing obvious yet. Rod caps all jiggle side to side a tiny bit, nuts and pal nuts all there. The plug is installed in the block by the oil pump pickup.
Eyeballing crank thrust shows less than 0.010".
With no obvious damage visible so far, does it sound reasonable to take the rod caps off one by one to see if anything is wiped? If they're not "wiped", is plastigage an okay "quick and dirty" way of checking clearance?
Do the same with main caps?
Does this sound reasonable?
I'm assuming I then need to check the cam journals/cam bores...
What do you all think? What else should I check?

[Rus Curtis]

Never worked on an L-head so I'll just ask some questions.   The knock you hear, does it continue after building (at speed) and then letting the engine idle (so you can raise the hood and listen)?  I'm wondering if you can isolate (front/back/top/bottom) with something like a stethoscope (a pipe works pretty good too).

You say no engine serial number.  In my SM there are different oil pressure readings below S/N 44417 and above S/N 44417.  Early has higher readings, later has lower readings.  Any other way to date your engine?

Are you running an oil filter system?

What kind of oil are you using?

[squidtone]

Rus,
I only heard the knock under load, at higher RPM's. I could not hear it at idle, or revving with no load.
My only experience with spun bearings on connecting rods was my son's subaru engine. It only made a knock when revving, but when we took it apart a connecting rod bearing was indeed spun and it wiped the crank pin pretty bad.
I didn't want to let it get to that point on my Jeep, so I've parked it and taken the pan off to start inspecting.
But to continue answering your questions:
I use 10W-40 oil with the classic bypass oil filter system. Oil is clean, filter is fresh from last summer (probably 800 miles on the oil change).

I don't know what year this engine is. It's a geared cam engine. Does not have the large rear bellhousing flange (indicating a "late" built engine). Oil pump is aluminum. 641087 block, but with with a weird stamp. I'm assuming it is from a stationary application. see pic.

I'm about to pop off some rod caps today I hope. I'll report with what I find there.

[Bob W]

A visual check of the main and rod bearings, and then plastigauge check is a very good idea.

[Bob W]

And the oil pickup for clogging and air leaks.

[squidtone]

Thanks fellas.
I did take apart and clean the oil pickup last summer, and the float, still "floats" too. No cracks in pickup elbow tube.

I took off all connecting rod caps.
What I found was -0.010" connecting rod journals with Clevite bearings.

Nothing is "spun". The bearings look worn, old, and, well, kind of corroded. There is a little trash embedded in them, but that is not distressing to me in an old engine like this. The bearing material is all even; no worn through layers of a different color.

I reinstalled and torqued each cap with plastigage.

Conrod 1:  0.003"
Conrod 2:  0.0045"
Conrod 3:  0.005"
Conrod 4:  0.0045"

Keep in mind the "resolution" of plastigage allows me to decently estimate the "half thou".

I measured the journals with a micrometer I inherited. (The "mike" is in good shape, but the stamp on the box says 1948, so I'm thinking it's a little past "cal")

RodJournal 1: 1.9275"
RodJournal 2: 1.9265"
RodJournal 3: 1.9270"
RodJournal 4: Neglected to measure

This tells me that whoever machined the crank took off 0.001 or so too much, or it's just wear.

The journals don't look too bad.

I took off the center main cap. The bearing shell looks pretty good, but again, just old and corroded, or etched. Not much trash at all in the bearing babbit.

I measured the clearance:

0.003"

I did not take off the front or rear caps yet.

Willys specification for mains and connecting rods is 0.0003" to 0.0029".
Every measurement I took exceeds 0.0029". In some cases by a couple thou'.

What do you think the chances are these clearances are the culprit for low oil pressure?
Does a 0.005" clearance in a connecting rod make a soft knocking sound?

I"m sure it's getting obvious I don't want to do a full rebuild even though that's ideally what should happen here. I don't mind "cheating" and just doing a bearing job (I've had success on other projects doing this), but I've never experienced this kind of low oil pressure problem and that's why I'm asking all the questions....

Any thoughts or comments welcome...even darts and jabs 

[squidtone]

Update:
The main bearings are also 0.010" under.
All bearings are Clevite brand
Both the connecting rod and main bearing shells have date codes of 1964 and 1965. I presume this engine was "refreshed" in the '60's but it still has "STD" pistons.

I looked into what thisi engine block is too. There is a thread on the Willys M Jeeps site about 641087 engine blocks. They describe the progression of the 641087 over it's life and break it into 4 series. My engine block has attributes of both series 3 and series 4.
Only two freeze plugs, but NO large bell housing flange, and some casting features that look like series 4. A strange block.

[athawk11]

I'm not a machinist, but from my experience, your journals and bearings look pretty darn good.

[Bob W]

The bearings and crankshaft journals don't look too bad. Sounds like your bearings have a bit too much clearance and your oil pressure is a bit too low.

[squidtone]

The evidence so far lead me (with fingers crossed) to that conclusion too.
I'm in the same boat as athawk11 in that I'm no machinist, but I did once rebuild a small block ford that had large tapers in the bores and really worn out bearings. I ridge reamed it, re-ringed it, polished the journals with a string and 400 grit sandpaper, put in new bearings, took apart and cleaned sticky lifters and the darn thing ran awesome.

So, with no red flags at this point, I have begun a parts search for main bearings and connecting rod bearings. Now for the slippery slope:
Since mains will require engine removal, I'm considering doing a ring job also (I've had the head off and it does not have big ridges at the top so I'll lightly hone it). And maybe valves, guides and springs.

But I'm finding that many suppliers have no stock of Sealed Power parts. This is mainly online vendors. It seems that NAPA has most everything, but they're probably 30 percent higher cost. On the bright side, they are offering 20 percent off on purchases over $150.

The nail biter is how I'll cut new valve seats. I'd love a set of Neway seat cutters, but for now that would exceed my budget.
I may hold off on that since I can do the valve job in-chassis later although at the cost of yet another head gasket set.
thanks for inputs.

[squidtone]

I've spent several hours looking for bearings. There seems to be a shortage out there for Clevite and Sealed Power bearings. No one has them in stock. (At least in the 10 or so places I've looked).
I think I'll have to go with Crown or Omix.
I found that even there I'm having a hard time finding anyone who has stock. I ended up finding the main bearings on Amazon, and the rod bearings on Summit Racing.
Walcks has stuff, and it appears it's either Crown or Omix. But even so, they're a bit more pricey.

Oddly enough, if I buy single Rod Bearing pairs, it's cheaper than buying a package of 4 pairs.

I am going to stew on this and purchase in the next day or so.

By the way, are the dowels that keep the bearing shells in place supposed to pop out of the caps easily? seems like that would be a bad thing...I wouldn't want the dowels to slip out and contact the crank while in motion. I may loctite them (retaining version of loctite aka "green") in place...any objections?

[aboyandhisdog]

Dave,  did you check with Rock Auto?  They seem to have a few rod and main bearings.  No idea if they have the sizes you need.  https://www.rockauto.com/en/catalog/jeep,1949,willys,2.2l+134cid+l4,1420894,engine,crankshaft+main+bearing,5220

[Bruce_W]

 NNNOOOOOO! Do not use Loctite  or anything else to secure the dowels in the block or caps! If you do, you will hate yourself later, or I or someone else will hate you. The part that fits in the block or cap is larger than the part that fits into the hole in the bearing, so the bearing itself holds the dowel in its hole. The part that fits into the bearing is shorter than the thickness of the bearing, so it will not contact the crankshaft. If the bearing wears thin enough for the dowel to contact the crank, you’ve got plenty of problems already.
BW

[squidtone]

I checked Rockauto. They are "out of stock" on main and connecting rod bearings (0.010"'s)

Okay Bruce, good advice on NOT loctiting in the dowels. BUT, it seems as though the person who refurbished this engine in the past lost the dowels (which I NOW realize should have a step in them to prevent them from moving out to contact the crank) and put in STRAIGHT dowels with NO step! They drilled out the bearing shells to allow the home made dowels to fit. But that means they can slip out and contact the crank!
Gah.

I will probably buy some new ones which I see some vendors sell, or make some. I have a lathe at work.

[stony]

Dave:  in the “old days” they would shim the bearings.  In your case it might be worth a try.  I would love to see someone do this (not me LOL).  Seems like you are in the perfect position to try it.  Here is a link:  http://deckwartaperedshims.com/index.php  Good luck!