Low oil pressure 360 amc

[OLD 9]

I'm having some oil pressure issues with my AMC 360 in my 79 CJ5 . The pressure is good, about 40-50 when cold but as it warms up it drops down to around 5 or so at idle. I've had the oil pump rebuilt with a NAPA kit and it seemed to help a little, but not very much. Switching to 20-50 oil might be part of this. The engine was supposedly a fresh 5000 mile ago rebuild according to the previous owner. I replaced the old mechanical gauge with a new SW one so that’s not the problem. The only thing left that I can think of is a bearing problem. Has anyone had a similar problem? Any ideas?

 

[mtnwhlr]

[QUOTE The only thing left that I can think of is a bearing problem. [/QUOTE]
I think you hit it on the head. If it is a fresh motor I would say the bearings have to much gap or its not as fresh as you think it is and they are wore out. You need to pull the pan and see what shape the are in. If they look new buy some plastic gauge and check the gap.

 

[OLD 9]

&*%#, I was hopin' it could be something else, like the timing cover where the pump is but you're probably right

 

[Purple77CJ7]

Did the PO replace the cam and cam bearings? AMC' s have more issues with cam bearing wear and low oil pressure because they get oil first in the system. I have replaced lower bearings and not gained any oil pressure, and rebuilt the oil pump,too. So I'm at cam and cam bearings myself. I have a 401.

 

[jeepboy45]

same here...

Its probably your cam bearings.

I have about 40 at startup, and about 2 or less at idle.... and I know for a fact its my bearings... Good thing is AMC's will do ok at LOW oil pressure... NO oil pressure isnt good.

 

[Purple77CJ7]

Old 9 be careful running 20-50 oil. In colder weather it can cause the distributor gear and cam gear to chew the teeth up, because of the viscosity. Weak link on AMC's. I have been there done that!

 

[007]

I run 15/40 in every single thing I own, but that's just me. I'd run Lucas Oil Stabilizer in the 15/40 and mix it at about 20-25%. Makes a difference.

As for the winter, I'd go with a thinner oil, but keep the Lucas in it to balance it out from cold to hot (after engine is warmed up).

 

[OLD 9]

Thanks for all the help. I asked this question on an AMC site and one of the answers I got was that 10 PSI or so, is a normal hot pressure in newer AMC V8s.
LOW OIL PRESSURE 360 AMC - The AMC Forum - Page 1
I'm hoping it isn't major, I have no place to pull the motor right now. Guess I'll put a few more miles on the new oil then cut the filter open and see whats there.