Oil pressure problems

[Gunslinger]

Oil pressure seems to be an issue here, I just had new bearings and rings put in the old engine, Oil pump is the high flow aluminum version, we went through it and checked the by pass, cleaned it up, put in what seems to be the right gasket and I put in Castrol 10w30 oil.  So now when I drive, the Oil Pressure starts out at 40 with a cold engine, slowly drops, after about 5 miles I'm down to 10 lbs and headed for the garage.  No funny sounds from the engine, valve train isn't clattering, rods arn't knocking.  Do I just have a bad guage?  If I let it run it will get down to less than 5 on the gage, with no engine noise, I'm confused here.  >:(What do you guys think?

[Carls_jeep]

Is that 5 psi at idle or at, say, 35 mph?

[Gunslinger]

5psi at cruising speed, thats whats got me worried

[Carls_jeep]

I would be more suspicious of the lube pump and/or gasket than anything else. Since it isn't knocking we can assume the bearings and journals are ok. I doubt the gauge is bad but you could try a different gauge just to be sure.

[Gunslinger]

Thanks Carl, I'm in the process of changing the pump now, once I give that a try I'll re-post.  From what I understand the size of the gaskets in the pump is pretty critical as they control the end play on the pump and consequently the oil flow and pressure.  I may have to regasket if I mess one up.

[Gunslinger]

Well the oil pressure saga continues, I've replaced the pump a couple of times and I changed oil, went to a straight 30 weight Shell Rotella T, Still have the same problem, when I start up cold I have 40 psi, as it warms up the oil pressure drops, if I drive about 3 miles it goes down to 5 psi at 2500 rpm and 0 at idle.  

I changed the oil pressure gage with a new one so I'm confident thats not the problem.  Also I find no leaks anywhere.  This engine only has abour 10 miles on a rebuild so I'm wondering is there something that the builder forgot to tighten up, bearing caps or something that would cause this?  I'm at a loss on this one.  It doesn't make any noise but I'm afraid that if I drive it at all it will get real noisy real quick!

Help!

[Carls_jeep]

Did you look at the old bearings? Were they undersize? You said it don't knock so was there some paper shims under the mains or rod caps?

An old Indian or red neck trick was to use paper as a shim to take up wear.

[Gunslinger]

We put in all new bearings, had the crank ground and polished, 10 under on the mains, 20 on the rods.  Thinking about the oil pump, I tightend the cap so it was pretty tight and their is no end play on the shaft, now I'm wondering if that is too tight, should there be some end play in the oil pump shaft?

[rocketeer]

You should read this:

http://www.gpwjeep.com/lubrication_system.html

Larry

[Carls_jeep]

  WHAT? Only one cam bearing in the block!!!!! Well, I see a world of trouble there. Think throw away engine here.

I think my engine has been rebuilt because the Jeep has nearly 100,000 miles on it as best I can tell. Now I am wondering if my block has been machined for replaceable bearings because it holds about 50 psi hot at idle. I am not real sure about that because I just don't remember for sure but I will check. It's raining here now or I would take it for a drive now.

Hmm, a worn block could be the problem. Gunslinger, what was the oil pressure BEFORE you rebuilt it?

BTW, does the Gunslinger handle mean your a Fast Draw artist? I am and still have my guns and rigs.

[Gunslinger]

I think we got our wires crossed Carl.  This is a long story, but the engine I have in the jeep now is not the original, the first one was bored 80 over and wore out, when we took it apart we found the crank was cracked, that and having to sleeve it meant the only thing I kept was the oil pump and the head.  I found a cj3 engine out in South Dakota on a picker weekend, it was an original Willys rebuild with standard pistons and .003 wear.  So I had a guy put in new bearings and rings and do a valve job.  This engine was a compressor engine so it only had valves in 1 and 3.  So that is the engine in the jeep now.

So the oil pump on the old engine held 40 psi at 2500 rpm all day long.  But its been serviced since then and I think not so well.  So today I went to Midwest Military and bought a NOS oil pump, I'm going to put that on so that I can completly eliminate the oil pump from the game.  If that doesn't solve the problem I'm going to take the jeep it to the local shop 3 miles from here and have them drop the pan and measure the bearings and crank.  I'm thinking the bearings may not have been plasti-gaged correctly when installed.  Wish me luck, I'll keep you posted.  

The Gunslinger handle comes from my other passion, I'm not an action shooter, but I do like to take Sam Colts Government Model  of 1911 with me and drive the jeep to the range when I feel nostalgic for those loud noises!!!

[Gunslinger]

Hey Rocket, thanks for the web site, Ilooked that over and it makes sense.  Thanks

[Carls_jeep]

Two best weapons used in WWII were the M1911A1 and the Cal. .30 M1 Carbine. Easy to carry, easy to shoot and dependable under any conditions. A man should never be without one or both of them, preferably both with lots of ammo and magazines and a Jeep to go with them.

[mud pie]

Two best weapons used in WWII were the M1911A1 and the Cal. .30 M1 Carbine. Easy to carry, easy to shoot and dependable under any conditions. A man should never be without one or both of them, preferably both with lots of ammo and magazines and a Jeep to go with them.

I am appalled !!  

How could you not mention the M1 Garand !!

Can you tell which one I own ?  

Actually, I own all three.....

[Carls_jeep]

Ahh, the Garand! Yeah, I carried one in Boot camp and the NG but I found them to heavy and the metal butt plate hurts my shoulder with repeated firing. I did own a Tankers model of the Garand one time but I sold it and should have kept it.

I remember the first time I fired my 1911. Walked down to the range after paying for it and a box of ammo. stuffed some cotton in my ears, loaded it and fired one shot. Unloaded it, went back to the shop and bought a good set of ear plugs and returned to the range and continued shooting. MAN, that .45 is LOUD as HELL. Still have the ear plugs and the .45.