Topic: 1/2 quart oil gone but little on ground

[bammerman]

My mechanic is lost on this and asked me to ask all you smart guys out in forum land.  There is little to no oil on the ground, when you pull my oil cap there is a lot of pressure (blow back is what he called it) he isn't sure if it is normal for these types of jeeps.  What happened was we replaced some gaskets, etc... "front of jeep not oil or valve he had to pull off the belts and that front piece of the engine" and I drove maybe 50-60miles and 1/2 a quart is gone.  No smoke out back end so I do not think I am burning it unless the CAT is and I am not seeing it.  Basically he asked me to see if anyone has had this issue with their jeeps before and what to look at next.

[sharpxmen]

My mechanic is lost on this and asked me to ask all you smart guys out in forum land.  There is little to no oil on the ground, when you pull my oil cap there is a lot of pressure (blow back is what he called it) he isn't sure if it is normal for these types of jeeps.  What happened was we replaced some gaskets, etc... "front of jeep not oil or valve he had to pull off the belts and that front piece of the engine" and I drove maybe 50-60miles and 1/2 a quart is gone.  No smoke out back end so I do not think I am burning it unless the CAT is and I am not seeing it.  Basically he asked me to see if anyone has had this issue with their jeeps before and what to look at next.

tell your mechanic to take a compression test - if there is a lot of blowby, no leaks and you are missing 1/2 a quart in 50 miles it is likely that you have some broken piston ring that probably start eating the piston if not broken a gash into it yet. this has nothing to do with the front crank pulley (or harmonic balancer) seal which i am guessing that's what your mechanic has replaced.

are you sure you measured the oil level correctly - that is a lot of oil to be missing in 50 miles.

compression test will tell you if there is an issue with a piston/rings.

[VA_YJ]

You could have a compression problem, as pointed out, which would explain the pressure in the crankcase.  Normally, this would cause smoking.  You can check the condition of the plugs when you do the compression test.   Some other things to look at:

There is a breather tube that runs from the top of the valve cover over to the intake.  Sometimes , particularly with older engines, the oil can get sucked out of the valve cover and accumulate in the intake.  Some install a "catch can" to deal with this.

Another possibility is that the front or rear crankshaft seal is leaking.  Check for leakage, particularly in the area he worked on last - front crankshaft seal.

[bammerman]

(or harmonic balancer)

Yeah this is what we replaced, it was going bad.  The seal on the oil pan was leaking a bit but he put some silicone in there and it stopped.  Previous person I guess didn't do a very good job.  I will show him these ideas, thanks.

[Sine Deviance]

I personally think it's blowby ending up in your intake. 1/2 quart is a bit excessive but mine was pumping out about a quart every 500 miles before I fixed it. If this is the problem you can pull off and clean the valve cover and PCV for starters. Chrysler also makes a replacement PCV valve and runner that is supposed to solve the problem, I don't know if it works though. A second option is a catch can. I fixed mine by cleaning the valve cover and the PCV thoroughly. Cleaning the PCV and getting all the gunk out makes it able to vent more efficiently, meaning crankcase pressure goes down, and as a result the oil blowby problem gets better or stops completely.

My mechanic is lost on this and asked me to ask all you smart guys out in forum land.

Don't take this as an insult to you or anything, but if your mechanic can't figure out what happened to some missing oil on his own or by using his own resources, he's not a very good mechanic.

[bammerman]

Don't take this as an insult to you or anything, but if your mechanic can't figure out what happened to some missing oil on his own or by using his own resources, he's not a very good mechanic.

None taken. I would say the same thing but I only stopped in to see him on my lunch, he had around 8minutes to look at it at max.  I am going back tonight for him to dig in deeper.  He said since I will have some time before that to get ideas.  Now if I go back and sit there with him for an hour or so and he can't figure it out... new mechanic ftw

[sharpxmen]

I personally think it's blowby ending up in your intake. 1/2 quart is a bit excessive but mine was pumping out about a quart every 500 miles before I fixed it. If this is the problem you can pull off and clean the valve cover and PCV for starters. Chrysler also makes a replacement PCV valve and runner that is supposed to solve the problem, I don't know if it works though. A second option is a catch can. I fixed mine by cleaning the valve cover and the PCV thoroughly. Cleaning the PCV and getting all the gunk out makes it able to vent more efficiently, meaning crankcase pressure goes down, and as a result the oil blowby problem gets better or stops completely.

Don't take this as an insult to you or anything, but if your mechanic can't figure out what happened to some missing oil on his own or by using his own resources, he's not a very good mechanic.

that would be the first thought (the plugged fitting and/or valve cover) but at 1/2 quart in 50 miles i don't think that's the case - it's either leaking out (lots) or an error in measuring the difference (in case is not ring/piston issue but in that case should've been the same before replacing the seal)

x2 on the mechanic

[Jeffy]

Well, I wouldn't give up on the mechanic just yet.  8 minutes isn't a lot of time to do much of anything and you'll get dozens of answers from people who have had similar issues with their Jeeps.  I'm sure he knows it's either going one of a few different places.

[Sine Deviance]

that would be the first thought (the plugged fitting and/or valve cover) but at 1/2 quart in 50 miles i don't think that's the case - it's either leaking out (lots) or an error in measuring the difference (in case is not ring/piston issue but in that case should've been the same before replacing the seal)

I dunno, if his PCV or runner are clogged really bad he could have some seriously high crankcase pressure and that would push quite a bit of oil out. But yeah, the new main seal makes the whole thing a little sketchy.

I would say the same thing but I only stopped in to see him on my lunch, he had around 8minutes to look at it at max.

Well, I wouldn't give up on the mechanic just yet.  8 minutes isn't a lot of time to do much of anything and you'll get dozens of answers from people who have had similar issues with their Jeeps.  I'm sure he knows it's either going one of a few different places.

I didn't know he only had 8 minutes to look at it. I assumed the mechanic had already had the Jeep for some amount of time

[aw12345]

With that much oil disappearing to a leak down test, any decent repair shop that does engine work should own a leak down tester. Is a little more work than measuring compression but gives a more accurate reading and it tells you where the leaking air is going. If the cat is good you will see very little smoke or any at all those things do a pretty good job of burning up oil smoke. If a leak down test with a warm engine shows let than 10% leakage per cylinder then the cylinder walls and rings and all valves are sealing properly.

[bammerman]

We are going to do a compression test in the next few days.  We tried looking for a leak last night and can see fresh oil behind the air conditioner pump.  I put dye in the oil to target the leak but cant get my light behind there, have to take pump off to see.  I need to get me one of those mirrors that can bend

[neale_rs]

Consider removing the CAT to see it is smoking before the CAT.

[bammerman]

Well the cat isn't clogged.  Next step is the compression test.  I hope I do not end up needing a new engine.

[sharpxmen]

Well the cat isn't clogged.  Next step is the compression test.  I hope I do not end up needing a new engine.

did you drive it since? is it missing the same amount of oil every 50 miles? the oil has to go somewhere, so if it's not in the cat or blue smoke coming out then you're losing oil somehow. at least the compression test will tell you if you have problems with your pistons and rings.

[bammerman]

It is all over the valve cover and underbody.  It is being forced out of every where it can it seems.  The blowby is really hard.  Yea I drove it everyday since first posting.  The oil only gets pushed out when I make the drive from Carson City to Reno at highway speeds.  While doing normal town driving it doesn't do it.


*Edit* I did add a can of seafoam to try to loosen up the pistons (incase they were gunked) and it seems there is more leakage now.