Weird leaking or burning oil...

[8gti9]

Hello All and Merry Xmas,

I have a 2003 Liberty Sport 4x4. I started it this morning to warm up, after about 10-15 minutes of idling/warming I noticed a smell of something burning. So I look under the vehicle and I saw smoke coming out of the rear passenger side oxygen sensor (post CAT) and also some oil. So I opened the hood and looked at the pre-cat oxygen sensor on the same side and it was normal, no smoke or burning. So this got me baffled, after getting back from the store I let the car sit and cool down for about an hour, I checked the oil level and it was just at the line between "ADD & SAFE".

I guess the question is...how come it's only coming out of the "post-cat" oxygen sensor and not the "pre-cat" if I am truly burning oil? Also no CEL or any warning lights on.

I only use 5w30 full syn every 5k-6k miles

 

[Porkchop]

Check The valve cover gasket bet ya thats The leak

 

[John3seventeen]

Like Porkchop said check your valve cover gasket! Common occurrence.

 

[8gti9]

Thnx for the replies and suggestions. I will check in the morning for the leak in the VCG. But to me it doesn't make sense on why it would be burning oil and the smoke would come out of the bung of the oxygen sensor.

I will shoot a short video of it in the morning. thnx again.

 

[John3seventeen]

Thnx for the replies and suggestions. I will check in the morning for the leak in the VCG. But to me it doesn't make sense on why it would be burning oil and the smoke would come out of the bung of the oxygen sensor.

I will shoot a short video of it in the morning. thnx again.

Cause thats where it drips - mine did the same thing!

 

[CactusJacked]

I'm curious how oil from a valve cover leak could make it's way down the exhaust pipe, up and over the cat converter, and make it appear as though it's coming out of the post-cat O2 sensor bung? All without getting burned off on the way down, which it would before getting very far. Btw, nothing should be coming out of the O2, it should be sealed. Is the sensor missing? Hopefully the video will shed some light on the subject.

 

[Joejeeper420]

I'm curious how oil from a valve cover leak could make it's way down the exhaust pipe, up and over the cat converter, and make it appear as though it's coming out of the post-cat O2 sensor bung? All without getting burned off on the way down, which it would before getting very far. Btw, nothing should be coming out of the O2, it should be sealed. Is the sensor missing? Hopefully the video will shed some light on the subject.

Mine is doing the same... It doesn't travel down the pipe... It drips onto that lower section where the 02 sensor is... Right at the last rearward VC bolt is "wet" with oil... If you look straight down... You'll see the o2 sensor / exhaust pipe... It's definitely coming from my valve cover.... Whether its the gasket... Or maybe one of the bolt gaskets... Has yet to be determined... Try re torquing the valve cover bolts first...

 

[Joejeeper420]

Also smells like candles burning....

 

[8gti9]

Well, I tried shooting a video of it with my dslr (5x actually) but it's too windy here in Fort Carson. But there's definately smoke coming out of the oxygen sensor. I checked for oil leaks from the VCG and header and down pipe and I didn't see any at all, not even a oil drip in my driveway underneath the Jeep where it's always parked at. I will have to try shooting a video of it when it's not so windy here.

I ended up taking the oxygen sensor off and inspecting it and it looked normal, re-installed. During on the test drive I can smell a hint of burning oil in the cab. I guess I just gotta keep an eye on my oil level once a week.

 

[John3seventeen]

It drips straight down onto it! Small drips at first - can drive you crazy trying to find it. If you don't think so just keep driving it like it is. It will eventually get bad enough that you can spot it. But plan on buying an O2 sensor as well!

 

[Porkchop]

Really u think oil can come out th 02 sensor just replace the valve cover gasket , soon the smell will make it stink bad enough in the cab you will do it anyway.

 

[doolop]

Everyone who has posted on this is right. Vcg is bad. Replaced mine with new and still leaking I'm going the way of high temp rtv in hopes of stopping it.

Sent from my DROID RAZR using Tapatalk

 

[TwoBobsKJ]

Guys, you've gotta trust us - IT'S THE VALVE COVER GASKET!! :mad3:

The oil drips off the cylinder head, drops straight down on to the cat (right at the 2nd O2 sensor), then the smoke rises directly up to the cowl where the cabin air intake is located. Your HVAC fan ***** the smoke into the cabin where it is blown into your face making you nearly sick. There is no oil drip in the driveway where the Jeep is parked because any oil that drips when the truck is parked will land on the cat; right after shutdown it will be be burned off. And once the engine isn't running there isn't enough oil pressure or splashing beneath the valve cover to create a drip.

The valve cover gaskets on 3.7's that have steel valve covers are notorious for going bad; the later engines have plastic valve covers that use a different gasket design. So just replace the valve cover gasket(s) and don't worry about tracking down a phantom oil leak from another source.

Bob

 

[8gti9]

ok...I'm gonna have to look deeper into the VCG leak. thnx guys

 

[dude1116]

Makes sense since 02-03 KJs have the vertical Cat's and the O2 sensors are closer to the engine bay. Mine are a bit closer to the trans.