Oil pressure issues on my 258

[raser13]

Hey guys and gals, need your help. I've got an 80 CJ5 that originally had a chevy 350 crammed under the hood. I had to many issues with the 350 so i ripped it out and put a AMC 258 i6 / 4.2l out of an 83 concord in it. The concord had sat a while before i got it. But the engine fired right up and purred like a kitten .

Now that i have it in the jeep it still starts the first hit on the key. Don't even need to hit the gas pedal.

My problem is when it's cold it reads 50psi both idling and at speed. When it gets warm it goes down to 0 psi no matter what i do. I take that back if i rev it waaaay up it will read like 5psi. I have a stock mechanical gauge, and a replacement one that i just bought to double check the gauge. Both read the same.

I don't have anything pluged in to the two gromets on top of the valve cover. Would that make any difference? I don't have power brakes or a stock air breather so i have them going anywhere. The motor doesn't have any leaks. And i am at least getting some oil up to the top of the motor. I can see it when i look in the oil fill spot.

Any help would be great. I don't want to keep running the motor like this and risk blowing it up.

 

[Lumpy Grits]

Your SURE this is a mechanical gauge?
Please post a picture of the gauge and pluming you now have.
Look at this for a replacement.
Oil Pressure Gauge. Black Dial, Mechanical Oil Pressure Gauge.

BTW: What weight oil are you using?
LG

 

[raser13]

Running 10W-30 in it right now. I'm having trouble getting my phone to upload pics for some reason but here's the sane set up that i have.

 

[Lumpy Grits]

YUP-It's mechancial.
What brand?
If the engine is not making noise-You have oil pressure.........
The first noise you hear in the AMC 258 i6 / 4.2l with low OP is from the tappets.
Can you post a picture of where the oil line is come'n from the block?
BTW: 15W-40 or 20W-50 are very good choices for these engines.
LG

 

[raser13]

Ok. Now that my phones cooperating here's some pics of what I've got.






I hope someone sees something that I'm missing. Please help.

 

[raser13]

Btw i have bled the line for the guage since that pic was taken. Still reads like the stock guage.

The new guage is made by a company called equus. It was just the cheapy $20 one from o' rielys.

 

[Lumpy Grits]

Never do the 'cheap' on engine gauges. Especially, the OP and water temp.
Where is the oil line come'n from on the block?
Where's your fuel filter?
Ditch the rubber hose on the fuel line and run a hard line from the f'pump to the regulator. That length of rubber hose is a 'heat magnet' that can lead to vapor lock since you don't have a fuel return line to the tank.
WTF-is the rag and open port deal on your valve cover?
Your suck'n all kinds of dirt inside that engine every time you lift the throttle.
A socket extension to plug a vacuum port-REALLY
LG

 

[raser13]

The pic where the oil guage line was coming out of the block didn't load right. I fixed it and it's the top one in the post with the pics.

Yes i know this puppy is jurry rigged all to Hades. Right now I've got just patched together just long enough to get the thing running. I fully intend to cap all the uneeded vacuum lines correctly and redo the fuel system the right way once i get the bugs worked out. Btw the two fuel filters are under the jeep. One is back by the tank before the electric fuel pump. And one is inline up against the frame just before the line enters the engine bay.

The PO had this thing all patched together for the 350. I'm amazed any of it worked. Originally there was nothing but rubber fuel line. He also had some kind of metal caps capping off all of the lines comming off the tank except the one comming to the engine. He didn't have any filters in line. I've got a new tank and enough line to do re run the fuel system. Just needed to find out the final locations of everything.

The vac lines got plugged with what i had laying around just so i could get the motor running and timed. But while doing that i was looking for overheating issues and such and stumbled upon this issue with the oil. So i haven't had time to replace my quick fix patches with their permanent counterparts.

The rag in the valve cover is there because my local parts stores have to order the check valve that goes there and I'm waiting on it to come in. I put the rag there as a temp filter so i could keep moving forward on this. I realize some dust is getting past it but it should be minimal.

I'm not dumb enough to drive it like this for long. It's just a mock up so i can get it all changed back over from the chevy 350.

 

[raser13]

I am going to ask the noob queastion though. I usually deal with stock aplications where you just take off bad part and repace with good one. So i really don't exactly know how to route them. Since i don't have the stock air breather where should i route the pcv valve ? And should i just cap off the front spot on the valve cover? Or is there somewhere else i should route it to? I know dumb question but I've never ran up against it.

 

[Lumpy Grits]

OK-That's weird-Your first picture of the oil line at the block was not showing when I made my post--
That line is in the correct port on the block
This link will help with PVC routing etc .
Table of Contents
LG

 

[raser13]

Ooo, that's a handy link! I've got that one bookmarked. And thanks for the info. Any ideas on the wacky oil pressure? Or do you think it's just the pump doing it's final hurrah?

 

[Lumpy Grits]

I don't think it's the pump.
I think it's the cheap gauge your using---
When was the last time the oil and filter was changed?
LG

 

[raser13]

Just before i fired it up for the first time. About a week ago.

 

[raser13]

Both the stock and replacement guages are reading the same though. One i could say yeah it's a bad gauge, two makes it hard to say that.

 

[Bent]

You can restore some oil pressure to these motors by removing the plate on the bottom of the oil pump that holds the pump gears in and having a machine shop resurface the side the gears contact. The gears wear the plate down and allow oil to escape around the gears instead of being squeezed between them. A low buck method is to use a piece of 200 grit sand paper on top of a granite tile to remove the wear on the plate. You'll need a new gasket also.

 

[Lumpy Grits]

Both the stock and replacement guages are reading the same though. One i could say yeah it's a bad gauge, two makes it hard to say that.

IT would-BUT, if you truly had "0" oil psi the valve tappets would be make'n LOTS of noise and the engine wouldn't run 'rite'. Is this engine making any of this noise at any time?
Who's oil filter did you use(Wix was OEM)? How much oil did you use? How gum'd up is the inside of this engine?
Again-Your talking about cheap China made gauges here--
LG

 

[Hedgehog]

A thought .... What would happen if the oil filter bypass is allowing all oil to .. well.. bypass the filter? There is obviously oil moving through the engine. If not there would be BIG trouble in a big hurry.

 

[raser13]

There is at least oil pumping through the engine up to the rockers even when reading 0. I just figured it was so minimal that it didn't read. I can open the oil fill cap and see oil moving. The lifters do make a little noise but no more than what i normally hear out of these engines. Definitely not just self destructing. I've had a pump go bad on a stang i had as a teen. That was a horrendous sound. That's kind of how i know something weird is going on.

I did get a pcv valve and grommet on it today and ran it to the vac line on the carb. So no more extention in the vac line. And added a mini k&n filter to the front tube. It's a funny thing to see but it works.

Is there something that could block off the tube that the pressure guage is plugged into but not stop the oil flow to the motor? Is there a secondary location that i can plug the oil pressure guage into the sytem to get a possibly a different reading?

 

[Hedgehog]

Here is something you could do. Detach the oil line from your gauge. Put it in a big container. Trust me on this, you are going to deal with a lot of oil in a hurry. Start the engine for just a second and shut it off. If there is some sort of sludge in the line it will come out. If you don't get a lot of oil... that won't be good at all.

 

[Lumpy Grits]

Here is something you could do. Detach the oil line from your gauge. Put it in a big container. Trust me on this, you are going to deal with a lot of oil in a hurry. Start the engine for just a second and shut it off. If there is some sort of sludge in the line it will come out. If you don't get a lot of oil... that won't be good at all.

The real downside to do'n that is the fact you have seriously drop'd OP to the whole engine.
LG