Goop in the oil fill cap area...

[CSM diesel]

I have a '03 libby with around 60k miles. MPG's have been acceptable (around 19mpg) up until this winter. Now it gets around 12.5 to 13 mpg. And now there is a white-ish colored goop inside of the oil fill cap neck. I believe it is coming out of the hose for the crank case vent. My commute is very short, 1.5 miles to work.

I just tuned up the libby last month, new plugs, synthetic fluids, air pressure is good in the tires, etc.

Is it possible that the o2 sensor is bad? Computer is not happy?

PCV valve?

Thanks,

Ben

 

[JeepJeepster]

What brand oil did you use?

Yea, its usually a good idea to change out the PCV valve at least once every 30k or so. They are pretty cheap and easy to change.

Yellow pudding is normal for short city driving and cold weather driving. A good syn oil usually helps keep it from happening though.

Got a clean air filter? Lower mpg is normal for the winter, more so if you drive in the city. There is alot more friction on Jeeps in the winter since you have front and rear diffs and a tcase with oil that gets really thick when its cold.

 

[CSM diesel]

Mobil 1 oil has been used since it has been in my possession. There is synthetic lube in everything, diffs, t-case, and trans.

And the air filter is a clean K&N "drop in."

I just think it is the short commute and less than "up to temp" engine that is causing the substantial loss in mpg and the wonderful winter fuel that we get in Colorado.

My '92 xj with 167k miles gets better mpg than this thing, and I run 31x10.50 tires.

 

[tjkj2002]

Mobil 1 oil has been used since it has been in my possession. There is synthetic lube in everything, diffs, t-case, and trans.

And the air filter is a clean K&N "drop in."

I just think it is the short commute and less than "up to temp" engine that is causing the substantial loss in mpg and the wonderful winter fuel that we get in Colorado.

My '92 xj with 167k miles gets better mpg than this thing, and I run 31x10.50 tires.

You are right about why you are getting low mpg's,just think it takes 600* for the O2 sensors to start working,if you never reach full operating temps(at least 3-5 miles of driving) you are alway stuck in "closed loop" in the PCM.That means you are running on a preset program for cold starts,very rich fuel mixture,once the O2 sensors start working you go into "open loop" in which the O2 sensors are telling the PCM how to adjust the air/fuel mixture for best power and mpg'sThe short commute is also creating sludge in your engine,which will happen if the engine never gets upto full operating temps for very long periods of time,will happen even with synthetic oils.

At least once a week take the KJ on a nice long drive,at least 10-15 miles to "blow the cobwebs out".

 

[CSM diesel]

tjkj2002: I agree. Do you know if there o2 sensor(s) are 4 wire heated or 2 wire? A failing 4 wire heated o2 sensor will not allow open loop to be achieved either as temps are never reached.

 

[JeepJeepster]

The ones Ive seen have 2 wires going to them. Ive never looked at the up-stream sensors though.

The KJ weighs around 500lbs more than the cherokee and the cherokee is geared alot better than the liberty. Wish the liberty had the I-6 and the AW4.

 

[jwheeles]

I had the oil changed in my Libby a week ago. I had the white/yellow goop on the oil cap. The guy told me that they saw this on about every other Chrylser/Dodge/Jeep product that came in. This is the first time that I've ever seen it but my former drive was 25 miles one way and now I am 4 miles one way to work. I have been wondering about it myself.

 

[Dave]

tjkj2002: I agree. Do you know if there o2 sensor(s) are 4 wire heated or 2 wire? A failing 4 wire heated o2 sensor will not allow open loop to be achieved either as temps are never reached.

The o-2 sensors are 4 wire - a 12v feed, ground, sensor return to the PCM and input circuit. This is on the 3.7liter. 4 sensors total. 2 before the cats and 2 after.

If there was something wrong with one of them I thought it would throw a code. Otherwise they should be ok.

If you have a CRD it is possible they are set up different and my manual does only show the gas systems and not the CRD..

Dave

 

[indianrefining]

I had the oil changed in my Libby a week ago. I had the white/yellow goop on the oil cap. The guy told me that they saw this on about every other Chrylser/Dodge/Jeep product that came in. This is the first time that I've ever seen it but my former drive was 25 miles one way and now I am 4 miles one way to work. I have been wondering about it myself.

"The guy" must not be very observant. This is going to happen with any vehicle which frequently makes short trips and doesn't get warmed up enough to cook the condensation out of the oil. It's not something exclusive to Chryslers, Dodges and Jeeps.

 

[a4dp]

"The guy" must not be very observant. This is going to happen with any vehicle which frequently makes short trips and doesn't get warmed up enough to cook the condensation out of the oil. It's not something exclusive to Chryslers, Dodges and Jeeps.

I've heard several people having the same problem with dodge trucks. In my previous car I used the same oil and drove the same mileage everyday. I never had any problems with the goop stuff. I think it has to do with the plastic filler tubes, but I could be wrong.

 

[indianrefining]

I've heard several people having the same problem with dodge trucks. In my previous car I used the same oil and drove the same mileage everyday. I never had any problems with the goop stuff. I think it has to do with the plastic filler tubes, but I could be wrong.

I've noted the same thing (the "goop") with both Fords and Chevrolets.

 

[a4dp]

I've noted the same thing (the "goop") with both Fords and Chevrolets.

Must be an American manufacturer problem. Either that or Audi is just immune to it.

 

[offrovering]

ive never had it on any vehicle i have had except the jeep. though the rest of my vehicles have been foreign

 

[ShafferNY]

I just changed the oil in my '03 for the first time since taking ownership of it. There was about 1/4" of this white goop in the filler neck.

Rather than pour fresh oil down the filler tube and flush all that crap into the engine, I took the time to remove the filler neck and completely clean it out.

Oddly enough, once I detached the filler neck from the passenger's side head, that's where the white goop seemed to stop. It didn't look like there was any inside the head.

It leads me to believe that the filler neck stays relatively cool once the engine warms up, especially being that it's plastic and somewhat isolated from the engine.

I too only drive a mile or so to work every day and usually the temp gauge hits the normal mark just as I'm pulling in.

I'd be curious to see if this happened with a redesigned filler neck; one made out of aluminium perhap. Something that would disapate the heat all the way up the filler neck.

 

[ShafferNY]

Just as a side note.

Since I changed my oil this past Saturday, the yellow/white goop is already starting to form in the oil filler cap.

 

[JeepJeepster]

What oil did you use Shaffer?

I also believe it has to do with the location of the oil filler cap. Hot air and oil goes up in the filler tube and cools causing condensation.

 

[Dave]

What oil did you use Shaffer?

I also believe it has to do with the location of the oil filler cap. Hot air and oil goes up in the filler tube and cools causing condensation.

1) I changed oil brands for one oil change to Pennzoil Syn. and got mega goop.

2) Went back to Mobil 1 and no goop. (very little anyway). I was going to change to Valvoline Syn but now not sure. We'll see.

3) We had a prior thread on this and in that thread I thought I narrowed it down to POSSIBLY the fact that the filler neck is plastic and doesn't get as hot as the engine metal so it's not burning off. This was a wild a$$ guess on my part though. I do not know for sure.

4) My Cutlass does not get goop. My GMC truck never got goop (200,000 miles and still running strong and no goop). I do most all the maintenance and all the oil changes myself so I know this for sure...... As a matter of fact no other vehicle I have ever had got goop and I have had a bunch.

5) So it must be jeep KJ goop. I do not know what elce to think. I do know that I want to be goopless.

Dave

 

[JeepJeepster]

When you say 'My GMC truck never got sludge," where did you put the oil in on that truck?

With two of our Jeeps you pour the oil right in the valve cover and the other goes right in the push rod area so of course youre not going to have sludge build up in the oil filler neck b/c it doesnt have one. Were not having a problem with sludge building up in the 3.7, its just the oil filler neck and I do believe youre right about why its forming dave.

Im going to switch to Valvoline syn on this next oil change dave but it wont be tested till next winter. Ill try to remember and post my results.

 

[offrovering]

out of curiousity, how does the filler neck come out? I wouldnt mind taking mine out and cleaning, then watch to see how much builds up, how quickly.

thanks

 

[JeepJeepster]

It just bolts to the head..