My Willys 3A and 3B Community
3A, 3B, DJ Technical Knowledge Base => "Original"-- Technical Questions, Answers, Observations => Topic started by: JimVillers on March 18, 2016, 08:47:25 AM
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We just assembled an engine after a complete rebuild.� We primed the oil pump and are using 30W oil (single weight).� �The tub is off the chassis so we installed a universal oil gauge. It has a new oil pump.
What is the "normal" oil pressure?� Our gauge is showing about 20 psi with the engine running above an idle and close to zero at idle.� I pulled the fitting for the oil gauge and it squirted with vigor and volume.� �
Should we be worried?� Pull the engine to investigate?� My only thoughts would be to look for an air leak around the oil pickup.
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I would be concerned with zero at an idle. I run 20W-50 in mine and at idle, when warmed up, it is at 20psi, unless it it really hot out, it might drop to 10. As soon as a give it gas, it, it goes up to 40psi.
Rule of thumb is 10 psi for every 1000RPM.
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I might first try a different oil pressure gauge...
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We put the tub on the chassis this morning. If I didn't do it this morning, it would be two weeks before my son and his trailer would be available again.
I will try a different gauge and some other items to check the pressure. The engine seems to run too well to have anything seriously wrong.
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I run similar to G-nome. I can get to 50 psi before it�s warmed up, but it tends to hover around 15-20 at idle when hot.
I have read that that having around 6 psi at warm idle and 20 psi at 2000 rpm when warm is acceptable and within specs on these old flat heads.
On a older worn in engine, I would point you toward a clogged pick up, an oil gauge issue, a weak pressure spring in the oil pump, and to do a compression or leak down test.
On a fresh rebuild�with a known good gauge, I would suspect the new oil pump. Reproductions are known to have occasional issues.
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Is your oil filter set up correct? I believe it plays a roll.
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Would a missing timing gear oil fitting produce those numbers on a fresh rebuild?
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I have the little oil squirter installed to lubricate the timing gears.
I am not sure of anything special about setting up the oil filter; 90 degree fitting to the hose to a 45 degree fitting to the outside of the canister. The hose comes straight out the bottom to the fitting on the timing cover.
The starter is now out to be converted from a 12V to 6V so I cannot test anything until Monday or Tuesday.
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Did you mess with the orifice in the timing gear squirter? Originally they were .070" and later WILLYS changed them to .040" to help with oil starvation in one of the bearings. Easy to check with a numbered drill bit. If its still a .070 you can easily braze the hole up and redrill it.
But 20psi at above idle is well within acceptable numbers.
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An update and some thoughts.
Second oil gauge reads the same, almost zero at idle and up to 20 psi when reved.
We changed the oil pump from the new pump back to the old pump, no change in oil pressure.
My thoughts are that there must be a large internal oil leak. The pump will pump a large quantity of oil and it has a pressure release valve to limit the maximum pressure. I inspected a stripped block to get any ideas to the cause. My guess is that the internal plug with the slotted head is missing.
Has anyone heard of this plug missing and what the symptoms were? Any other thoughts?
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Have you tried a thicker oil?
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There are a couple plugs in the oil galley. If not installed, you would have a hard time keeping the pressure up. The re-builder might have pulled them to clean the block...then forgot to re-install them.
Credit for Photo belongs to Flat Fender Fever!!!
(http://i1195.photobucket.com/albums/aa397/athawk11/Willys%20internal%20Oil%20Plugs_zps39num3ir.jpg)
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I don't see how you could get "20 psi with the engine running above an idle" if one of those plugs were not installed. But maybe?
Two pumps with the same results kind of rules out the pump.
The other side of the oil galley feeds the oil filter. If I were going to trouble shoot this problem I'd first try blocking off the oil filter feed hose. Next I'd pull the timing cover and check the timing gear squirter.
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The good and the bad ..... I blocked the oil filter line as suggested with the first oil pressure gauge and it read the same pressure as the dash gauge. Zero at idle and 20-25 max when reved.
I pulled the pan to inspect the two internal plugs and they were both in place, a slotted plug in the galley and a square head plug in the pick-up.
Is there a gasket under the pick-up flange? I don't remember one and it does not look like it has a gasket. A air leak here could cause a lack of volume.
I am hesitant to pull the front cover to check the front oil squirter which I specifically remember installing and adjusting. The replacement front pulley is VERY tight and it will be destroyed trying to remove it.
My next step will be to force oil into the system through the oil filter hose to see if there is a big leak someplace. I plan on adapting my pressure brake bleeder with engine oil. It will make a mess but hopefully provide some understanding of where the oil is going. I have never tried this but it sounded like a good idea.
After that, we'll measure the main bearing gap with plasti-gauge. This is not rocket science, just a simple engine and there must be something that is not right somewhere.
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Yes, I believe there is a gasket under the pick up.
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I am still looking for the cause of my low oil pressure. I pulled the engine; yes there was a gasket under the oil pickup flange.
I checked the bearings and the appear OK; between .002 and 003 inches (I think that that is within spec). There must be a "smoking gun someplace.
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I found a main bearing specification of .001 to .0025.� If that is correct, my bearings are at the outside limit or slightly above.� �If that is the specification I have probably found my problem.� Any thoughts before I get new bearings and have the crank reground?
For background, the block was line bored when all of the other machining was done. I do not know if that would affect the final bearing clearance.
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Just to report progress, we pulled the front pulley; first pulling off the sheet metal, then welding a short length of pipe to the remaining pulley hub and welding bolts to the pipe. See the picture below. What a B*#.
Everything looked OK so we pressured the oil system with 20 psi of oil from my pressure beader. The real oil flow was from the little squirter for the timing gears.
That leaves the main bearing clearance as the most likely cause of the low oil pressure.
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If you mentioned the float I missed it...
Is it in good condition? No serious leaks at the joints?
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I have thought about the float.� It joint seems "loose" since it does not have a seal but I think that joint should be under the level of the oil.� I have another float so I'll clean it up and see how it feels.
Good suggestion.
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I think you are right, the joints are below the oil level....
Just thought I'd mention it...hoping for a simple "fix"....
One other thought...
The relief valve springs and plungers are installed in both oil pumps?
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I don't think the bearings being 5 tenths over would lower the oil pressure to 0 at idle.
Have you talked with an engine builder?
Maybe check with them over at the CJ2A page. Lots of knowledgeable folks over there.
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A cracked upper pick up tube could contribute to low pressure.
Also, check the "note" below...
(http://i1195.photobucket.com/albums/aa397/athawk11/th_db3879cfec29cea75f2a093c394b5ef8_zps3wqklzlc.jpg)
I have no idea why this is printing so small.
Essentially, the old oil jet was drilled with a .07" aperature. The newer was changed to a .04" aperature. It is recommended the smaller jet be used.
I have heard folks will close this hole off and re-drill it.
Tim
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(http://i1195.photobucket.com/albums/aa397/athawk11/db3879cfec29cea75f2a093c394b5ef8_zps3wqklzlc.jpg) (http://s1195.photobucket.com/user/athawk11/media/db3879cfec29cea75f2a093c394b5ef8_zps3wqklzlc.jpg.html)
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How much end float did you have on the crank? .002-.003 bearing clearance should not have caused your problem. You could try blocking off the oil filter feed to see if something is wrong with the canister. Two oil pumps with the same results means the relief valve is working or seated. Very strange you haven't found it. John
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Hawk .... Good catch, my timing gear oil jet is larger than my largest gauge, 1.5mm (0.06 inches) so I must have a 0.07 jet.� Easy fix.
The end float is an interesting question, I'll measure it tomorrow.� I guess that the idea is that the #1 main lubricates the thrust bearing and if that is too loose, it will loose pressure.�
Oil-Leak .... I blocked off the oil line to the filter and it did not change the oil gauge readings.
Great thought.� It may not be a single issue but a number of independent items.� I very much appreciate your (plural) comments.
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I rebuilt my engine last year. I am going to yank it as soon as the weather stays above 50 degrees for more than a day. I suspect the problem lies with the rear cam seat. Why do I suspect this?
1) tried two different oil pumps - Same result
2) tried two different gauges - Same result
3) I used to work in a machine shop and I am confident it both my initial measurements and my final assembly measurments.
4) End-play was checked and rechecked upon disassembly.
5) I pulled the oil pan last year to check all the galley plugs - all installed
6) removed the front timing cover and inspected the aperture. I had previously brazed and re-drilled a .040 hole. I checked with a wire guage all OK.
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Sorry computer glitch- My thoughts continued.
One thing to remember, oil pressure does not equal flow. I believe I have enough oil flowing. But somewhere in the system there is a gap that would have gone un-repaired or un-machined during my rebuild. The only thing that fits this would be the rear Camshaft housing at the rear of the block. The front housing contains a bearing and is easily repaired by boring and bushing. However, the rear housing is cast iron and a part of the block. It is not easily repaired. This is likely the only thing, due to location and a lack of replacement parts that was left untouched. When did measure it it was .006-.008 out of round. I did not think this was too awful a the time but I am convinced that at low RPM there is enough bleed by to reduce the oil PSI to near 0. While at 2k RPM the PSI is 22. I would bet $100 bucks, that if that was bored and bushed to a 0.001-.002 tolerance my at idle PSI would be 20 ish and at 2k it would be 35-40 ish.
I would bet that you are dealing with the same issue.
Just my thoughts after thinking/checking on mine for the past year.
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Peter .... Thanks you; an idea and logic that I had not though about.� I will stop by the machine shop on Monday and look at the rear cam "bearing".� It is one of the few items that we have not measured or investigated.�
Finally someone who has experienced the same problem. There is nothing new with these old engines, only "old" problems that we have not heard about. I'll post what I find.
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Another piece to think about. When you do research you can find references on the web Cj2A website and other places on how to install a bearing into this location. It is possible but, if you do find you need this repair I recommend a different repair. Have your machine shop line bore the 2,3rd, and rear bearing housings to accommodate new cast iron bushings. They are cheep $15 or less each and you can predrill the hole for the oil port. The labor to perform the task will be less than trying to retrofit a bearing assembly. If the machine shop does it right and sets the bushing up with a 0.001-0.002" (OD) interference fit and they shrink it with liquid nitrogen, it will slip right in and within seconds it will warm up. No locktite, no beating with a hammer, and no special pulling tools in awkward positions and it WILL NOT come out. The fits will be restored to factory, with the same material, fit, and finish.
This is the company I used to use when repairing bearing fits in my old shop.
http://shaverkudell.ca/wp/products/eze-sleeves-list/the-original-cast-iron-series
-Peter
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Peter .... Thanks; I'll visit my machinist tomorrow to decide on a repair plan. I'll update your when I learn something.
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Peter ..... It looks like you were spot on. The cam bearings were VERY loose, .005-.007 or so. I attached the specifications which show it should have about .001 clearance for the oil film.
It was good that I pulled the engine, the bearings were already showing some wear from metal-to-metal contact.
I'll post the fix when my machinist decides on what he will do.
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Glad I could help. I am a Reliability Engineer, essentially my whole job is to systematically pick apart things to find out how/why they failed and how to eliminate that mode of failure. I did not want to pull my engine this summer and not know what I was getting into, so I thought long and hard since October about what the problem could be. I am glad that you have confirmed the problem.
Again, there are a bunch of different ways to repair it. I myself like simple/straight forward approaches. I strongly feel that cast iron sleeves shrunk in with Liquid Nitrogen are the best most cost effective solution. Keep in mind yes, for years and years interference bushings were pounded in with a hammer but, liquid nitrogen will keep the fit concentric and ensures you that the oil port will line up exactly where it needs to go. Oh and one last thing, you can get one hell of an interference fit (they will never come loose EVER).
Keep me informed on what they do for the repair!
Peter
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Peter ..... Just to provide an update.� We first tried a new cam shaft to see if that might provide a solution.� It picked up a thousandth or two but not enough t get close to the specification.� The block is being sent to another shop to have the journals bored and bronze bushings installed.� They are using bronze because that is what they are familiar with and what they used on a similar jobs on old Triumph engine.
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Cool beans, if they have a history of that type of repair I am all for it. I only made my recommendations on the basis that the machine shop had not made a similar repair before.
Good luck!!
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Peter .... I have great confidence in the shop. They normally work on vintage race engines but also do the one off type of stuff that we hobbyist drag in. They have all of the fancy stuff like a flow bench for tuning the head to a stationary dyno to run and tune engines before installing them into the car. There is just not time on the track to break in an engine.
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Six weeks later and I am still waiting for my block to be repaired. When it left the "in waiting" area, the machinist changed his approach. He felt that since the holes in the block were very round, he decided to do the machining on the camshaft. He ground down the cam bearings, sleeved the cam bearings to increase their size and then grind down the cam bearings to fit the block. He said that it was easier to accurately ground down the cam to fit the block than bush the block to fit the cam.
As you said, there are several approaches to solve the problem. I'll report oil pressure when the engine is assembled and running.
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If the bores are indeed round as he said, sleeving and grinding is pretty normal. Honestly, whats not normal is for the housing (cam bores) to be "round" if they are worn. Let me know how it works out!