1967 CJ5 with 225 and no oil pressure.

Did a "dry" compression test and found one weak cylinder.

Cylinder # PSI
1 80
3 145
5 140
2 125
4 145
6 135

Plan to leave it for now and get the oil pump rebuilt but it will be a couple of days.

 

Try this, if memory serves me correctly the spring behind the hex plug is ~.50 Dia. (maybe .375?) - remove the hex plug and shim it with a steel ball bearing.
Then see if the pressure comes up.
This worked on my first CJ5, a 1970 V6. I learned how to drive in the beast and had it in high school. For some stupid teenage reason my buddy
and I tore the engine done at 48K cause it was leaking oil badly. My dad wasn't real good at vehicle maintenance...
A few months after the rebuild it lost oil pressure, I was near my Uncle's shop and swung in there. He handed me the tools and told me to remove
the hex plug and then he put in the ball bearing and reassembled. That fix lasted another 50K until the poor thing rusted out to nothing.
Then motor was still going strong.

_Dan

 

The oil pump on a 225 is fairly simple.
I've only had one failure in my Jeeps. The shaft from the distributor to the driven gear in the pump decided to disconnect.
I never heard of anybody else that has had this happen but it is worth a look.

 

Thanks for the tips. I plan to pull it tomorrow after work and see what I have.

 

Pulled the pump this evening.
It looks to have new gears and gaskets.
I removed the retaining nut and spring for the piston. They have the yellowish looking spring but no shims as far as I could tell.
I could not get the piston to move. I tried one of those extendable magnets to see if it would move at all and it didn't. This seemed odd to me but without a manual I can't be certain.

 

I would not expect to find shims under the hex cap for the spring. It might take some patience in getting the piston out as it is deep in the housing. You might be able to slide a long 1/2" bolt down inside the piston and **** it a little to grip the piston to pull it out, provided it is the cup-type piston. I have also seen a piston that has long thin stem on the spring side you can reach with a long-nose pliers. Either way, it would be good to make sure the pressure relief piston slides freely in the housing bore. If it is not seated at the bottom, you will not ever build oil pressure.
Quick question, is there spring tension pushing the hex cap off when you unscrew it from the housing? There should be at least some tension pushing the cap in to start the threads.
-Donny

 

Donny,
There wasn't any pressure on the cap. I did find the rebuild kit in the jeep and the other springs were there. According to the directions the yellow spring should have extended 7/16" but it was more like 1/4 - 5/16".
I checked the other springs and found the one closest to 7/16" (measured 5/8") and went with that. I realize that may up the pressure some but this particular spring wasn't coiled as tight as the one they had in there so expect some give over time.
I will reassemble everything tomorrow afternoon and spin the pump with a drill to make sure it primes and pumps.

 

Do not forget to pack it with petroleum jelly first.

 

Got it back together, yes I packed it with petroleum jelly, and spun the pump with an electric drill. Felt it prime and increase load on drill then noticed oil spraying out the passenger side of the engine. Turned out the oil pressure gauge line was old, brittle and broken in a number of places. At least I know there was pressure there.
I replaced the line and can see where oil is moving through it but the gauge still reads no pressure. My thinking is the gauge has been history for a while now and needs to be replaced.

 

I would still try to see if you can pull the piston out to inspect it. Who knows, it may not have even been installed upon rebuild. Even a small piece of garbage will keep the piston from seating, keeping pressure from building.
As Nick says, prime with petroleum jelly once you know the overpressure piston is seating properly.
-Donny

 

Pulled the distributor because something just didn't seem right. Turned out the oil pump drive shaft was not engaged with the distributor. I had marked the location of the rotor, on the body etc. but must have been just a hair off in my visual line up of the slot. Took about 6 tries to get it right but finally it dropped in and now we have oil pressure reading on the gauge.
Gee do I feel stupid but felt I would share my experience in case someone else runs into the same problem.

 

Does anyone have a guide line for comparing serial numbers and such to prove whether this is the original engine, tranny, etc.?
I know where to look on most cars but thought maybe things might be different on Jeeps.

 

There is a casting number guide that Joel put together here - nmr.mgh.harvard.edu/~reese/BuickV6CastingNumbersandInternalSpecs.pdf

We have a serial number registry in a sticky post at the top of the forum - that may contain some engine serial number or build date info. Pretty sure Jeep did not match engine and chassis serial numbers ever, at least not like the passenger cars. The later AMC engines had a build data, but no sequential serial number. The L134 and F134 Willys/Kaiser engines got a serial number, but I believe it was not matched to the chassis.

 

I was reading through all the posts before I commented to see if someone here commented about the distributor not being seated. Good call uncamonkey.

I had the dummy light oil pressure light staying on when I was messing with the distributor one time. I was pulling my hair out one trying to figure it out. I went ahead and gave up, tightened up the distributor with that keeper knob thing and.....the light went off.

More often than not on my jeep, the simplest solution has solved the biggest problems.

For those who read this in the future:........the last 1/4 inch or less of that distributor shaft is what engages the oil pump and makes it turn. The jeep can run with the distributor pulled out just fine and yet be completely disengaged from the oil pump. It doesn't look like its pulled out that much, but it's just enough to not make the oil pump turn.

I also figured out that if that oil pressure sensor gets wet, it will turn on that light as well.

 

No such thing of feeling stupid, we all have our moments, but I'm sure someone will read this thread and learn a thing or two.
Glad to hear you've got the oil pressure.

 

Thanks for the credit but it isn't quite deserved. In my case, the gear that is supposed to be pressed on the end of the drive shaft to the oil pump came loose so the shaft was spinning inside of the gear.
I'm happy you got it figured out.
I'll fight with Photobucket tommorow to see if I can post the picture of the parts.

 

If I remember right, isn't there a cotter pin or a shear pin or something on the end of that gear?
https://www.flickr.com/photos/mdmeltdown/3315192542/

 

There is a roll pin that holds the gear onto the shaft.

 

No guys, he is talking about the oil pump gear that has the shaft pressed on to it. Not the dist shaft. I have seen this happen only once in my lifetime but if it can happen it will and so infrequent that it is passed over by top notch mec's.