oil pressure mystery

So what would make my AMC 360 suddenly lose oil pressure (ZERO LBs pressure on mechanical guage) to where the valves are rattling, then after I pull over, shut down and check the level (full), re-start the engine and have it right at the correct pressures ( Up to 60 LBs at about 3000 RPMs) all the way home?
This isn't the first time its done it, either. The last time I just made a sharp corner and the pressure came right back up.
Could the oil pump lose its prime in these engines? Then re-gain it after killing the engine?

 

my thougnts would be loose timing cover bolts or leaky/leaking timing cover gasket
oil delivery and return go thru the cover
or..loose oil pickup in the pan
it's possible to suck air in thru either means

 

HHMM... the timing cover is tight ( I just spent hours installing a 1 wire ALT, so I've looked at it pretty close) there is no oil leaks on the outside of the engine at all (which is wierd in itself, I've never seen a JEEP not leak at least a little ).
UGG I hope its not an internal engine thing, I dont have a shop here and its been raining every day right as I get off work...(Maybe I should have put the top back on?)

 

it would be more of a suction leak, not a pressure leak.
check the oil pump cover bolts
check the oil filter adapter; it threads into the timing cover if I recall
look around the cover and see if the gasket is squished out anywhere, specifically the oil passage areas.
sometimes, you can put air pressure into the passages (oil pump cover removed) and detect a bubble leak this way thru the gasket, just short bursts of air.

 

I have seen engines with a nylon timing gear on the camshaft where the nylon starts to flake off and gets sucked up into the oil pump screen and plugs it, then when you turn the engine off enough falls back down to the bottom of the pan to allow the oil pump to work again aslo engines with alot of sludge buildup inside can do the same thing.

 

you might be able to remove the oil sending unit and blow some air to check the gasket that way.

 

this is all very true too.

 

:yt: Ford small-blocks are famous for that! I've dealt with enough of those that when I buy a new Ford project, the timing chain gets replaced ASAP.
I am under the impression that this engine is fairly fresh, although it does smoke a little on start-up (valve guides/seals), but I have been starting to wonder about the Timing chain.

<sigh> looks like I get to take the oil pump cover and/or oil pan off (one of these days...)

 

I would check the the oil pressure relief plunger, it might be getting stuck open, which is common on these engines.

 

I agree! the AMC v8 oil pump is similar to the vintage GM B.O.P, Cadillac blocks with the pressure relief plunger on the pump housing. Buy an oil pump rebuild kit. If that doesn't cure the problem, drop the pan and check the pickup screen. Small particals will clog it.

 

anyone have a pic of how that goes together/ location? I don't have all my technical reference books down here with me.
Can't do much with it for a couple weeks, anyways. no $$ to work on it this weekend, and gotta drive it to work next week. And I dont wanna screw it up for the trail run next weekend (I know, it could break then, too. But its a risk I will take...)

 

Look by your oil filter. The unit the filter is attached to houses the oil pump. 45 DEG to the dissy shaft. . If you look to the side there is a large bolt, aprox 11/16 i'm not sure, but that is the plunger, directley behind the oil filter.

If you need more help E/M me @ lissahutson@yahoo.com, I will walk you through it.