1998 XJR, 130,000 miles.

I have some oil 'blow-by' coming out of the full load breather, into the air intake. I initially installed a air-oil separator filter (the ones for air tools) in the breather tube, and problem solved. However, the amount of oil increased, and the separator was ovewhelmed, so I've now installed an even more intricate oil separator, basically involving a small paint can, rubber tubes, and a bunch of air filters - sounds cheesy I know, but it works, it's all painted and doesn't look too ridiculous under the hood of a jag.

My separator works fine; but I'm worried about how much oil is coming out, and why. I'm getting about 1/4 quart into the separator per week - this corresponds exactly to how much oil I have to add per week, so I don't seem to be burning oil, and no leaks. Why so much oil out of the PCV? Something is clearly wrong. The simple answer is probably oil getting past the piston rings (worn cylinder walls, ??). Maybe so. I haven't had a compression test yet, but the engine runs great, no noticeable loss of power, and no cylinder misfire codes (i.e., restricted performance never pops up).

Anyone have a guess as to why this is happening, and if there's any potential fix short of an engine replacement?[sm=vader.gif]
thanks in advance!

 

show us a pic . youve answered your own question..

 

Skan,

Have you checked to see if the part load breather is clear?

 

part load breather is clear - I suppose the P.L.B tube could be cracked, but I'm not sure if that would influence this or not. the hole from the cam cover is not clogged - that much I know.

genius...I attached a pic+diagram for my oil separator system. I've seen better, but this one works for me. Basically the full load breather goes first to an air/oil separator filter (for air tools), then into a small, black paint can that sits by the windshield washer reservoir, then back to the air intake. The diagram attempts to explain how the paint can is separting the oil. basically the top 1/2 of the can is stuffed with air filter material, the "in hose" goes down through the filter, dropping the oil below the filter material. I could have made a fancier one, but the paint can is easy to work with because I can pop the lid off, empty the can, replace the filter, and then close it air tight again.

 

not sure if the pictures attached - another try.....

 

Did you paint your supercharger and charge air coolers? They look like new.

 

Yes. I want my engine to look good for its funeral..

 

Skan,

Not so sure if a cracked pipe would causeyour problem, but you'd have alean code flagged.

You should make sure the actual pipe is clear, not just the cam cover orifice. I made up a blowby testerto attach to the part load breather port a couple of months ago, and used a cut hose from a junkyard engine for the fitting. The 45 degree angled fitting was completely blocked up with carbon. So I know it can happen, and I'd suggest making sure yours is clear. On an N/A AJ26, all you have to do is unplug the hose with the engine running and the resultant vacuum leak will confirm. I don't work on enough S/C cars to know if the result will be the same, but I believe it would.

 

might just be easier to replace the part load breather, which I'll probably go ahead and do -- but what do you mean by 'the resultant vacuum leak will confirm'?

 

That means if you pull the part load breather pipe off of the cam cover on a running AJ26 N/A engine, you get manifold vacuum sucking through the breather pipe. Unless it's blocked.

I don't know, and haven't researched, whether the same is true for S/C. I should think it would be.

 

It is the same

 

ive never heard of jag engine pushing that much oil out of the PCV.. in a week.. maybe oil is going to the head and just not returning thru the head bleed down holes.. and excessive amounts of oil are building up under the cam cover.. like the xj6 use to leak.
just a thought i had .. when i was watching t.v.

 

interesting theory genius .... not returning because down holes are clogged?? what could I attempt to do about this? I have no problems taking the cam covers off, but I'm not sure where 'head bleed down holes' would be.

 

I don't think the V8 engines have that problem. You could probably cipher it out by carefully checking oil level cold versus one minute after hot shut off, I don't know.

The point, Skan, is that if you have that much oil puking out of your motor, it shouldn't be hard to figure out. On a worn Nikasil engine with excessive blowby, all you have to do is pull the full load breather pipe off with the engine running: it will blow enough smoke that it looks like a teapot on the stove at roiling boiling.

My understanding is that, with the part load breather orifice or hose blocked off, venturi effect on the full load breather hose will suck excessive amount of oil out of the engine. I think that's what the bulletin about cleaning the orifice infers.

I would hate to see you incorrectly condemn a servicable engine, that's all. If you do in fact have that much blowby, you've done a good job in keeping it going as long as is possible.

Andrew Bernstein

 

thanks for the input guys. I'll replace the part load breather, and if it's still spitting PCV oil, I guess that's that. It still starts fine and doesn't misfire - idles slightly bumpy, but barely noticeable. I love the car too much to give up easily. Worst case scenario, I'll just keep adding oil until it won't start.