Engine How to address oil weeping out of crankcase push in breather?

[MJkid67]

I have an '85 CJ7 with the AMC 258 i6 / 4.2l and the engine with just under 100k miles. It weeps some oil through the crankcase breather (I can smell oil from the cab and it will drop a couple drips now and then). Engine pressure at dash gauge is good. I have not done a compression test on the cylinders. There are no leaks from the valve cover gasket or RMS. It has a carburetor.

Is this blow-by? What can I do to stop this? Thanks.

 

[TSB8C]

Could be blowby, or could be an issue with the PCV setup. If the PCV system is not allowing sufficient draw on the system (through the vacuum) then it has to escape elsewhere, hence through the breather. Check the PCV valve and hose(s) to the manifold vacuum source. You do need to do a compression test on each cylinder as well. Worn rings will allow cylinder pressure to bypass the pistons and put pressure in the crankcase, forcing oil out. Of course another question is whether the oil you are seeing is actually coming through the breather filter or possibly leaking out around the gasket/o-ring where the filter is inserted into the valve cover. If oil is being forced through the filter, then check the other items. If it's just oil leaking around the o-ring, then replace with a tighter fitting filter/gasket.

 

[MJkid67]

I believe the oil is getting by the rubber gasket/o-ring where the crankcase breather plugs in.

I'll do a compression test and get back to this thread with the results.

 

[KRUPP]

As usual, TSB8C's comments are spot-on. I'll add a recommendation though...

Blowby is normal with a AMC 258 i6 / 4.2l with 90k mile on it. Nothing alarming. A solution to the oil drips from the press-in breather is to get rid of the press-in breather. Instead, use a 90d elbow press-in fitting there at the valve cover and plumb a hose going to the underside of the air filter assembly. This is assuming that rear hose connection I see in the picture (a bit blurry) is your PCV valve with a hose connection to a vacuum port at the carb?
Your air filter assembly may or may not already have a connection for a hose. If not, you can make one fairly easily in a number of ways.

 

[letsgobrandon]

I thought they all did that,mine has for 30 years