Time to consult the brain trust.

1. Is there any kind of filter available for the "Full load breather hose?" I note that it sucks in all kinds of oil that winds up in the intake manifold and eventually gets burned. Some parts diagrams show a "restrictor" that goes between the hose and the valve cover, but I've never seen one in the wild.

2. I've read that, aside from external stuff like the intake, the only difference between the 4.2 and the 4.0 is the crankshaft stroke. Is this true? Could one get a 4.2 by just doing a crankshaft swap?

Thanks in advance for your input!

 

If the 4.2 has more stroke then fitting a 4.2 crank in a 4 would mean the pistons hit the head.

First ask yourself why there is so much fumes blowing out the breather. If engine is worn then piston blow by will give excessive crank case pressure ..you dont seem to say what problems you are getting other than the fumes get burnt in the engine which is normal. Is it using oil ?
Some engines use a catch can when blow by is excessive. Loads on e bay at little money so you can see the designs. Most go in the breather line to remove the oil and let the fumes flow on others vent to atmosphere via a filter

 

Yes, I guess if I'd given that a bit more thought it wouldn't have sounded so dumb. So, are the 4.2 rods a bit shorter, or are the wrist pins up a bit higher in the piston?

The full load hose is essentially a vacuum cleaner attached to a hole in the valve cover. It is going to suck in some oil. I've noticed a little puddle of oil inside the intake manifold of my car, and I noticed it on another 4.0 that I pulled the intake off of the other day. I note that my BMWs have a similar setup but all that air is sent through an oil separator. I note that the smaller, part throttle hose, or whatever it's called, does something similar but to a lesser degree. This just seems to be an odd setup - PCV with no filter. The engine uses a little oil but it doesn't seem to be excessive.

 

the valve cover has a wire mesh, restrictor is inside the outlet nipple. that combo makes your oil separator.

4.2s are mirrored and use a rubber diaphragm oil separator valve/pcv valve like on many euro cars. They will billow smoke if torn.

 

Well, that's interesting. Mine has nothing but the metal plate that acts as sort of a baffle. I pulled a cover last week from a 2001 XK8 and it, too, does not have any kind of filter, just the same metal plate. Are these mesh things removeable? As in, would many mechanics simply leave them out after, say, a valve cover gasket service?

 

mesh is inside the glued metal plate

 

FWIW,
Mine collects a small amount of oil at the bottom of the throttle elbow. The engine has done just short of 13K miles.

 

Thanks! I see it now.