Oil leak left side through rubber plug on side of valve train

It may be reminants of an old o-ring or rubber gasket material from your valve cover that is so brittle it looks and feels like plastic. Are your valve covers leaking oil onto the outside of your engine? A piece may have fallen jnto the valve train area and made its way ino yhe oil pan from a return oil opening in the block.

If it is leaking at the oil filter the previous rubber gasket may have stuck to the block. When the new oil filter was installed then the gasket was doubled and will leak.

Having worked on several cavaliers this year, I have found a tune up took care of the rough running condition, and all of them had valve cover oil leaks.
So consider replacing the valve cover gaskets and the spark plugs.

A vertical cover...I had to ponder that a bit. Still not sure. The valve cover sits flat on top of the cylinder head, with a gasket between them. The cylinder head is where your spark plugs are threaded in. The valve cover rests on top of the cylinder head. It's about 14-18 inches long and about 4 inches high, kind of rounded over so the valves and valve train will fit underneath. A gasket leaking motor oil is very common there, as a lot of oil is directed there and then splashed around to lubricate the valve train. The oil is supposed to drain through engine passages on down to the oil sump- the bottom of engine where oil is kept in the oil pan.

So if you have an oil leak, and it turns out it is the valve cover that is leaking, it's an easy fix-one of the easiest gasket replacements there is.

The only thing you might need to buy beside the gasket is any rubber parts that have been damaged by the leaking oil.
Check your radiator hoses, heater hoses, and vacuum lines, because motor oil will "rot:" rubber.
You need only replace hoses that are "spongy"and are wet with oil.
Be blessed.

This is how I replaced the rear valve cover rubber gasket seal on 1995 vt600 start by runing the bike very low on fuel a quart or so. On the set
ther's two screw on each side look closely about center of the set, there
probably 10mm bolts, Remove the set pull it backward, Remove the fuel tank 12mm bolt pulling it backwards will remove it from the rubber hanger
this will allow you to remove the fuel hose at the valve. install a cap to stop
the fuel. To remove the spark plug wires and boot on left side, two fingers
at the base of the boot and to fingers at the top of the boot note the plug
wire. ( boot body pull up easy). right side plug wire pull it up easy. At this point I removed the plate that covers the exhaust vavle 5mm allen wrech for clearence & the breather tube on top of the cover & removed the tie strab that holds the wiring to the left frame tube and pride it to the right side for clearence remove 10mm bolts lift the cover up easy have someone hold it up and slitely back, look close and pay attention remove rubber seal and go to the right side with it looking and getting it over the rocker arms and cam gear.wipe cover clean. thick greas on bottom of cover to hold the gkt in place sneak seal over cam & rockers and install on cover be sure seal is in place at the spark plug hole & breather area I used trans gel to holed the
gkt in place

The 3.1/3.4 engines are built the same way. The oil goes through the cam bearings then to the lifters, then the push rods to the rocker arms. The last engine I seen that had a weird problem had the cam bearings spun. Unfortunately there is no easy way to check for this problem short of disassembling the engine.

The other possibility would be bad lifters but loosing half of the engine lifters wouldn't be possible. Sometimes the pushrods wear on the contact areas also but not usually half an engine.

This isn't going to be easy, Good luck.

It may be the gromet for the PCV valve or it could be the spark plug rubber seal located in the valve cover if it is the type of engine that has the wires and spark plugs that go down through the valve cover, if this is the case buy a valve cover gasket with the rubber gromets that are located around the base of the hole where spark plugs fit through and install.

If I can remember,, check valve cover rubber where it seams with camshaft rubber on rear of cylinder head, the 1/2 moon rubber sits in a concave slot in head itself,usually removed, clean and reuse rubbers with a dab of silicone.

Yes the oil can cause the car to lose spark, the oil leak could be caused by the valve cover gaskets around the spark openings, but 9 times out of 10 it is the spark plug tube "O" rings. The top of the valve train comes off of the head, the "O" rings are between the two halves, that will fix the oil leak.