I have a D16Z6 swapped into my 95 DX. The car has had a heavy oil leak since I got it. I replaced the oil pan gasket twice thinking that was the cause since it was all over the bottom of the engine. That seems to have slowed some of the leak but there is still a heavy leak. Maybe a quart every 1000 miles. I used some Lucas to slow it up which worked somewhat but the oil is still leaking and burning off the exhaust so Id like to fix it right. I have degreased the engine a few times and put dye in the oil. My top suspect it the rear main seal. The oil is only on the backside of the engine but its getting onto the axles while driving and flinging everywhere so it makes it a PITA to diagnose. The distributor seal looks to be dry as well as the VTEC solinoid, valve cover gasket & head gasket. MY only question is that there is a black box on the backside of the engine that is covered in oil. Could be flinging off the axle or maybe it is leaking. I dont know what this part is. I assume some part of the PCV system or something. What is this part and is it a common source of oil leaks? I just want to know if you have any ideas before I go ripping my trans out. Thanks for the help.

 

So nobody knows what that black box is?

 

It's called a breather box. A simple Google search would have told you that.

 

if the pcv valve is plugged, the positive crankcase pressure can push out the rear seal.
then it drips right on the exhaust pipe.

 

Rear seal is most likely the issue.

 

Thanks for the info. Its tough to google something when u don't know what it's called grumble. I have replaced the pcv even though the old one seemed ok. Guess ill just have to tear into it and see what's up.

 

http://www.google.com/search?q=civic...ient=firefox-a

 

Is this the original factory installed engine? The reason I ask is if someone had the oil pan off before and removed the little baffle plate for the PCV excessive oil could get sucked in there and into the breather box. #8 in the diagram:

http://www.hondaautomotiveparts.com/...3-95+S%2CSI%29

Is smoke coming out of the exhaust?

Also you may want to remove the breather box and check the condition of the o-ring.

Otherwise it's probably the rear main seal which can be replaced with the engine in the car but it's a medium to big job. You'd have to drop the transmission and remove the flywheel or torque plate (whichever you have). You can avoid removing the oil pan by double-nutting the main seal housing studs that come through the oil pan to remove them, assuming you want to remove the main seal housing which is the method I would use (as opposed to just prying the seal out and hammering a new one in). It's much easier/safer to install the seal correctly with the main seal housing (#7 in the diagram) removed in my opinion. I recommend a tube of Honda Bond for this procedure.

 

I would think if the PCV valve was plugged then there would be no ventilation as manifold vacuum would be absent.

I think it works through vacuum not pressure (correct me if I'm wrong).

Excessive blow by might cause enough pressure to force oil out the seals, gaskets, etc. which I suspect is (one of the reasons) why higher mileage engines tend to seep oil more.

 

The car is a DX so the D16 was swapped in. He never said if the oil pan was off and I dont remember if the baffle was there when I had the pan off to replace the gasket. I think im going to remove the breather to see what I can see.

The crankcase builds pressure through the action of the rotating assembly. The PCV system does have vacuum from the intake but if the PCV valve is clogged there is no vacuum supplied to the crankcase allowing pressure to build which can cause gaskest to get pushed out causing oil leaks etc.