OP
Burning oil
- Thread starter mgroeger
- Start date
Oil enters the combustion chamber via two routes. One is by the rings. To test that just pull the valve cover cap and see if it puffs smoke. Two is the valve guides and that wont show on a compression test. Why are you testing the compression?
Agree with this plus those intake tubes can suck oil or it could be a torn valve guide seal which would go from nothing to sucking oil quick. Just looking at the plugs should tell you if you have a single cylinder problem.
OP
Someone mentioned compression test to see if the rings were bad.
I've never heard of the smoke coming out of the valve cover cap. I'm assuming that will show if the valve guides are bad? Please explain.
If the rings are bad the combustion gasses escape down into the crankcase and go up through the oil drain passages into the valve cover so you see smoke puff up there. Most of the leak is actually gasses blowing down into the crankcase with a smaller volume of oil pulled back up into the cylinder. It normally causes the engine to run like crap, but regardless that's why you pull the cap and see if you've got exhaust up there. Very common for high compression diesel motors to blow out the valve cover but like @Goatman says if your oil control ring broke it would do it.
Edit: the only evidence of leaking valve guides or seals would be crud in the intake runner around the valve, a dirty spark plug and missing oil, there is pretty much always vacuum sucking into the intake runner so there normally aren't any pulses back into the valve cover, especially not exhaust gasses
Another thing I'd add is be sure the size of your oil leak before you get too far. Everybody has their own way to describe a leak but it could be that simple. The way I see it a dirty oil leak is nothing to worry about. If enough oil is leaking that it becomes a clean spot you might take a second look. Mine leaks quite a bit but everything is still dirty. If I started seeing clean paths from the leak down and out I'd fix it.
OP
Thanks for all of the info. The "leak" I have is dampness, other than the tiny drip from the RMS it doesn't produce any marks.
Some of us older gear heads, (motors before the catalytic converters)... If your engine blows blue smoke on startup then goes away as the motor warms or if it blows blue smoke at idle and/or pulling away from a stop is valve guide seals. if it blows blue smoke all the time its rings, valve seals that are gone or just plain worn out motor, cylinder walls. The introduction of catalytic converters masks (burns off the leaking oil) in newer motors. Also a bad PCV valve can cause high crankcase pressure forcing oil to go places it shouldn't, change this first, (cheapest and easiest elimination). if it still uses oil, when engine is cold, pull the exhaust pipe from the manifold and fire it up, blue smoke means you have internal problems.
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All those things work great on my Ford six.
Our motors use a simple metered hole and I think it's called CCV, no valve to check, it's just a hole in one of those plastic bits connected to the valve cover.
Right, my bad. just a metered hole in an elbow, not a true PCV valve. still needs to make sure that this is working properly and not clogged up.
OP
UPDATE:
On Saturday I went over my entire Jeep in prep for an off road trip Sunday. I confirmed I still have the RMS leak and it is small. I noticed that the driver's side of the oil pan was damp and discovered that those bolts were at least 1/2 turn loose so I tightened that side up. Passenger side was bone dry. Only other place that was a little damp was that sensor thing that plugs into the block and has a wire harness on it next to the oil filter. I forgot it's name but it is a little damp around it but can't call it a leak.
I removed both "PCV" elbows and cleaned them out with carb cleaner. They were fine but I was shocked to see that fat elbow only has a tiny little hole for the air to pull through although I suspect that's to keep oil vapor from sucking in.
SO there were no sizeable leaks to account for the previous oil loss.
I put a brand new Mopar filter on and went up to 10w-40 oil and wound up just a tick above the full mark, as in about 1/4 qt too much. Not concerned about that.
Yesterday drove 80 miles each way varying from 35-75mph with 5 hours of off roading in between, the Jeep was literally running for 8 hours of a 9 hour day. Checked the level this AM and it is still spot on. Will continue to babysit.
Of note, I have a lifter tap now and I suspect that going to 10w-40 brought that out to be louder than it was with 10w-30.
On Saturday I went over my entire Jeep in prep for an off road trip Sunday. I confirmed I still have the RMS leak and it is small. I noticed that the driver's side of the oil pan was damp and discovered that those bolts were at least 1/2 turn loose so I tightened that side up. Passenger side was bone dry. Only other place that was a little damp was that sensor thing that plugs into the block and has a wire harness on it next to the oil filter. I forgot it's name but it is a little damp around it but can't call it a leak.
I removed both "PCV" elbows and cleaned them out with carb cleaner. They were fine but I was shocked to see that fat elbow only has a tiny little hole for the air to pull through although I suspect that's to keep oil vapor from sucking in.
SO there were no sizeable leaks to account for the previous oil loss.
I put a brand new Mopar filter on and went up to 10w-40 oil and wound up just a tick above the full mark, as in about 1/4 qt too much. Not concerned about that.
Yesterday drove 80 miles each way varying from 35-75mph with 5 hours of off roading in between, the Jeep was literally running for 8 hours of a 9 hour day. Checked the level this AM and it is still spot on. Will continue to babysit.
Of note, I have a lifter tap now and I suspect that going to 10w-40 brought that out to be louder than it was with 10w-30.