Question,
My 96 3.9L 4X4 ext cab 5speed manual engine oil pressure drops at idle giving a valve like clicking sound at stop lights, but it all goes away when driving. Any know fixes out there? Oil is high milege variety less that 1000 miles since last change and at the proper level. I did notice the air filter and filter canister is oily-dirty but not fresh oil.

 

I would put some lucas oil treatment in there. and that should help you out. what grade of oil are you using. I wouldnt go any thinner then 10w30. aslo how may miles do you have on your motor. your oil pump could be getting weak too.

 

Another thing you may want to check out is that the PCV system is operating well. (I've heard that when this system is not operating correctly, it can cause oily residue on the air filter)
The PCV valve is located on the drivers side cylinder head cover. If, when the engine is off, you remove the PCV valve, you should be able to shake it and hear a rattle. With the engine running, if you remove the PCV valve from the cylinder head cover, there should be a good amount of suction (put your finger by the bottom of the PCV valve [the part that would go into the cylinder head cover])
If there is no suction, make sure the hose is free of obstructions, and is hooked up correctly (should go from the PCV valve to the intake manifold). If everything is routed correctly, remove the PCV valve from the hose and than test for suction. Repair anything as needed.
The other part of the PCV system is the crankcase breather/filter (CCB). This is located on the driver side cylinder head cover. Obviously, as you can tell from the hose running to it, it gets its air from the air filter assembly. With the engine idiling, PCV valve installed, remove the CCB, and after a minute, hold a piece of stiff paper over the opening. It should be drawn with some force.
Again, make sure air is able to move through the hose for the CCB, and air is able to move throught the CCB itself.

Also, how far down does oil pressure drop when at idle? The specs for min. oil pressure at idle are pretty low for these engines (6psi). It's perfectly normal for oil pressure to be lower at idle than at higher engine speeds (since the pump is engine driven). However, if you have any worries, or the gauge definitly reads low (which mind you, since the gauge and its components are electrical, so they can't be trusted all the time), get an ACTUAL oil pressure reading. Low/no oil pressure is nothing to play around with, because if you wait too long, you'll trash your motor.

Anyways, just what jonnymagnum said.

 

if the engine is high mileage it could be the timing chain slapping the case too thats what mine is doing I just have to wait it out til spring then she gets a heart transplant....

 

ya mine has a nasty timming chain noise too. it's getting pretty bad. I just hope she'll last till summer when the 318 goes in her