Plugged cat? Funny symptoms...

[KJEfting]

'93 Bronco 351 E40D, 227,000 miles

It seems like my crankcase pressure is higher than it should be. I've got oil coming up into the airbox through the crankcase ventilator and I've also got oil coming up the dipstick. At lower RPM's, it's not much of a problem. But when RPM's are up for a sustained amount of time or I run it under a load, oil runs up the dipstick and onto the drivers side exhaust manifold. The motor seems sluggish and almost sounds like it's missing a little, even though I gave 'er a full tune up about 4K miles ago. Oil pressure is great and my compression is good. Do you guys think the valves are shot? $-) They aren't making any noise yet, but the truck does have a ton of miles on it. Could it possibly be a plugged cat? I've never known anyone that had a clogged up cat, so I'm not entirely sure as to what the symptoms might be. Any input is greatly appreciated. Thanks fellas!

-Ken

 

[Shadow_D]

I'm interested in knowing the answers for this problem as well. :-B

I have the same problems except I don't have the oil comming up the dipstick. I have however noticed that the Beast has a kind of a wet sound like it isn't burning all the fuel. It has also started to just die for no reason, it starts right up after it dies like nothing ever happened :huh: Maybe these could be related

 

[Yardape]

Is your pvc valve still sucking? Or is the vaccum line plugged with carbon at the intake manifold? Other than that sounds like worn rings allow compression to seep past the rinngs and create excess blow-by in the crankcase.

 

[firelt90bronco]

I fixed a 2002 Dodge Durango with the same oil in the air box issue. I took off the breather from the airbox to the valve cover and blew all of the sludge out and replaced the pvc valve. Your cats could be clogged, if so take em out. You can either replace them or run straight pipes like mine.

 

[Seabronc]

The normal path for the evaporative emissions for the Oil system is from the intake filter box, to the driver side valve cover, down through the oil return hole to the oil pan, up through the passenger side oil return hole to the valve cover, through the PCV valve to a vacuum port that is at main vacuum pressure level. If that path is restricted you will get oil back into the air box.

Like FireLT said, try clearing the external parts of the system first. If the rubber hose from the {CV valve is cruded up just replace it.

Not to wreck your day, but if your oil breather system is OK, you may have blow buy on one or more cylinders.

The CAT has nothing to do with the oil problem. However, a clogged CAT will cause severe power loss especially on acceleration.

Good luck,

>-

 

[ANFO]

I just went through clogged cats on a 93 5.0 I bought ~2 week ago. Mine was doing the same thing and would barely idle when I bought it, 87 kmi and it sounded like it was dead. I used air shears to cut a flap in the side of the front cat and gutted it, it was completely jammed up. I cut the second cat and muffler off (no exhaust past the muffler to worry about, long since rusted away), I replaced it with a new muffler, some pipe and a turn down. The truck went from night to day, once the engine could breath again it had all kinds of power. I dont know if it is the chiken and the egg but I pulled the throttle body and intake off, it was so carboned up inside the passage directly behind the throttle body was completely blocked off and it was far beyond carb cleaner. I cleaned it out with a large wire drill attachment I got from my father (no idea what it was for or where it came from, it was sorta like a cylider honer but no where near aggressive). I also had a bad: PCV, throttle position sensor, egr valve and sensor, o2 sensor and the plugs looked like ****. I lost oil pressure last week and it was due to the engine being so sludge/carboned up, I ran 2 flushes and dropped the pan to get all of the sludge out. I also ran sea foam through the brake booster line (holy smoke show, couldnt even see the house through it). My air filter totally black from oil.

I replaced every filter, the bad sensors, 1 vacuum leak I found due to weathered hose, plugs, wires, cap, rotor + all of the cleaning to the internals etc. and now I have great oil pressure, no more check engine light and she will burn the rear tires on dry pavement. It was nearly $700 in repairs from running clogged cats but it is running like a new truck. If it does turn out your cats are clogged I would pull the throttle body off and get an idea of how bad you interal passages are from running so much exhaust through the engine for so long. Definatley, flush, clean and replace all the filters once you have the cat issues worked out.

 

[KJEfting]

Thanks fellas for the info. I will let you know what happens!