258 Blowing Oil

[76'kee]

I can't seem to find a fix for my engine blowing oil out the filler cap on the valve cover. I've replaced the cap without success, I've made a new gasket out off cork for the old filler cap and it still leaks and I'm tired of the burning oil stench. When I had the valve cover off I inspected the interior and found it to be in good shape - the filler cap's on tight and properly. When I did the 2bbl carb swap I made sure I had an unrestricted breather cap installed on the valve cover, though there's no vacuum routed to it like a stock one would have to the air cleaner. But it leaked even in stock form too. The PCV is new and functioning, it has a good source of vacuum to it.....
So..... any advice?

[Simple Kind of Man]

How much oil is it blowin? Hate to say it but it could be a hole in a piston. That is what promted me to swap in a 360 in my J10.

[Crazy_Jeepman]

Yup sounds like bad blow by at the least, Compression Test is in order. Then a rebuild :(

[Don S]

..
76'kee;
... Oil in the air cleaner of the AMC six cylinder engines. It is a fact that many 258 cid engines were rebuilt to fix the oil problem and the overhaul did not fix it.

In the 1981 modelsThere is an air intake tube from the air cleaner to the valve cover. If the PVC valve is bad or partially stopped up the vapor flow in the breather tube can reverse flow-causing oil to enter the air cleaner.

... A PCV system is designed to be connected to the intake manifold to burn off smelly engine vapors. And there are three sizes of the valves.

... It seems there is a baffle in some valve covers designed to prevent oil droplets from being sucked into the PCV valve. But the oil is able to pool on top of the baffle and is so close to the to the PCV pick-up that it can be sucked up and sent to the intake manifold. The viscosity and /or temperature of the oil will make the condition act differently at times.

Perhaps a non breather oil cap and installing a breather tube from the air cleaner to the cover would help.

Have a good one http://www.michiganjeepers.com/forums/images/graemlins/popcorn.gif and CUL.. Don S..

[76'kee]

Blow by would be a bad thing, I'll throw the compression tester on it this week - thanks, I didn't think of that.
Before the upgrade to the 2bbl, I had the breather tube running to the air clearner and still had the problem. There wasn't much oil getting through the tube to the air cleaner itself. Now that I have a different carb set-up, I lost the stock airhorn type air cleaner and am running an open element type, losing the vacuum connection to the valve cover.
So, I installed a non-vacuum type breather when I tried the new gasket on the filler cap in the hopes it would help. I'll do the breather connected to the intake and see if that helps, then run the compression test to see what I get and go from there.
Thanks all!

[cherokeedoc]

Tom,
I'm anxious to hear how things worked out as I have had the exact same problem with my 81 cherokee 258. I've been tolerating the oil and filthy hands but would like to solve this problem of persistant oil seepage. I'm a bit concerned about the rebuild suggestions earlier, but will attempt to change PCV and vaccum hoses as suggested for hopefully cheap fix.