I replaced my stock y-pipe/cat with the jegs off-road pipe and used the non-fouler trick.

Ive had it on for about 4 months now and no cel! Even without a cat.

 

If it were mine I'd do the test from the TSB to determine if my plenum repair had gone bad, and unless I saw zero or negative pressure in the crankcase I'd leave the intake manifold right where it sits. And then after returning things back to normal I'd leave the vacuum gauge connected to the manifold, get the engine up to temp, and watch for that jiggling needle that indicates worn valve guide seals and might explain the oil consumption and premature cat failure.

As for the oil on the belly pan, if the TSB test procedure doesn't indicate a problem I'd probably replace the PCV valve with a dealer part just to get a nice comfy safe feeling. It's perfectly normal and safe to have some staining and a tiny bit of gooey looking oil residue in the intake of an engine with a PCV system. We owners of small block Magnums are the ones who often see it because we nervously peer inside the intake from time to time and we've got these broad, flat belly pans below the runners that collect the oil mist that settles out of the PCV air stream. Most folks never look past the throttle plates of their engines, most of those who do can't see the PCV ports anyway, and their intakes have nice downhill runs from their PCV ports to the nearest intake runners so there isn't much opportunity for puddling.

 

I did do the TSB before and after replacing the plenum. Got positive pressure both times (did not use vacuum gauge, used some soap and the end of my thumb over the hose. Since it blew bubbles, I assumed positive pressure of some sort). There did seem to be a little MORE positive pressure after I did the plenum. Haven't done the test since, but was actually planning to this afternoon for peace of mind. It uses 1 qt between oil changes, 170k miles. I assume that's fairly normal? Thanks.

 

I found a guy I went to high school with that owns a muffler shop. He actually agreed to put a Y pipe in place of the cat, put bungs in for the 02 sensors and everything. He said that the post cat 02 sensor did have some effect on driveability and was not just there solely to monitor the cat. The other exhaust shop said the same thing, and I also read this online somewhere ("speed tweaks" for magnum engines or something of that nature). Anyway, he said he'd do the Y pipe no problem, but it would screw with my fuel mileage. So that's what I'm worried about, or I'd go ahead and do it.

He's also the second guy that told me the magnaflow cat wouldn't last and I'd be putting another one on in 6 months if I used it. He sells the Catco cats, like the other exhaust shop (maybe they get paid by how many they sell, I don't know, but I do know the guy and he's pretty trustworthy).

Sooo...I dunno. Is it written down somewhere that the post cat 02 sensor doesn't do anything or where does everyone get that info? Just to make me feel better about Y-piping and non-fouling. Cuz that's the direction i'm leanin.

 

Take a look at this on post cat 02's if anyone's interested:

http://newsgroups.derkeiler.com/Arch.../msg00732.html

 

I suppose it depends upon your definition of normal. It's common enough, anyway. I'd be at least mildly concerned about any oil consumption exceeding a half quart per oil change interval, but lots of guys don't think twice about it.

Myself, if I don't see that telltale vacuum gauge jitter before then, I just replace the valve stem seals at the next excuse I have to get into things after 100,000 and no later than 150,000 miles. The darn things are going to leak eventually anyway, so for thirty bucks and an afternoon of tinkering under the hood I'll salvage that very considerable chunk of engine lifespan that's going to go away if I don't do it.

 

I did the tsb test again today, positive pressure again. No vacuum gauge, just soap bubbles. I did see a visible vapor coming out of the open hose that goes to the airbox when I had the pcv blocked off. Some sort of blowby, I guess, do not know if that's normal or not. And my definition of normal is, its 13 yrs old with 170k miles, and it runs and doesn't need rebuilt yet, so run it. Lol.

I will look into the valve guide seals, though. I'm not a mechanic and am not familiar with changing them, but I can figure it out. This will be after I decide what to do on the cat. I will follow your advice on the seals because you seem like a pretty smart fellow and I enjoyed the animated pic of the girl slapping her *** on your profile (or whatever its called). Nice. Now your profile will be perused en mass.

 

That's normal, unless there's a great lot of it or it smells of antifreeze.

That's a pretty liberal definition but if it works for you who am I to argue?

I'm a bit twitchier than most when it comes to maintaining my stuff because I just absolutely and to the point of irrationality hate broken 5h17.

It's not really all that difficult a job. Not in concept, anyway. Getting to those cylinders in the rear can be interesting in a painful kind of way. The only real trick to it is to snake a thin rope through the spark plug ports to fill the combustion chamber/hold the valves up to make it possible to put the keepers back. After doing a couple of cylinders you'll catch a rhythm and just cruise on through to the end.

I'm not a professional mechanic either. My only qualifications are distrust of repair shops and a history of perfectionism, both arguably irrational and the result of far too many unsavory experiences.

Must be someone else who's the smart guy -- there's no animated *** slapping girl in my profile.

 

I think I clicked on a picture of your truck earlier at work and scrolled through several pics at the bottom of the screen. Assumed all the pictures were tied to you somehow. I didn't ogle the pics too much, would hate to lose my job for studying the anatomy of that female's nether regions. Although I have lost jobs for more unworthy regions, er, reasons.

 

YOu can also use compressed air to keep the valves up. THere is a connector you can use that will go into your spark plug port in place of the spark plug.

That is if you have a compressor.