5.7 using oil, no smoke

[Schurkey]

1. In a world where tool-shaped objects are sold by companies like Hazzard Fraught, "Low compression" can be an inaccurate gauge as easily as a problem with the engine. VERIFY the compression tester before condemning the engine.

2. "Oil in the cylinders" during a compression test never made sense to me; how is the oil supposed to climb the cylinder wall on the intake-manifold side to seal the rings on the "uphill" side of the cylinder? I quit adding oil to cylinders decades ago.

3. A leakdown test is excellent for finding low-power, non-sealing cylinders. A cylinder can seal and have compression but still burn oil. This is especially true if the oil is coming down the valve guide
or sucked-through the PCV. There's a pretty fair chance that neither of those issues will show up in a leakdown test.

4. Any chance this engine has aftermarket valve covers? Aftermarket covers often have crappy oil separators. Any oil in the PCV hoses?

 

[thinger2]

1. In a world where tool-shaped objects are sold by companies like Hazzard Fraught, "Low compression" can be an inaccurate gauge as easily as a problem with the engine. VERIFY the compression tester before condemning the engine.

2. "Oil in the cylinders" during a compression test never made sense to me; how is the oil supposed to climb the cylinder wall on the intake-manifold side to seal the rings on the "uphill" side of the cylinder? I quit adding oil to cylinders decades ago.

3. A leakdown test is excellent for finding low-power, non-sealing cylinders. A cylinder can seal and have compression but still burn oil. This is especially true if the oil is coming down the valve guide
or sucked-through the PCV. There's a pretty fair chance that neither of those issues will show up in a leakdown test.

4. Any chance this engine has aftermarket valve covers? Aftermarket covers often have crappy oil separators. Any oil in the PCV hoses?

yep, the oil doesnt do anything during a compression test. It only works as an indication during a leak down test. You run the leakdown dry and then do it again with oil to see if you get a spike in compression before it blows past the rings

 

[thinger2]

Your saying it isn't smoking because it has a catalytic converter?

No, I think hes saying that the oil is blowing out the exhaust and is getting trapped in the cat

 

[Postmech]

Cats operate around 1800 degrees . That will reduce or eliminate oil smoke from exhaust. A quart every 60 miles, unless its going by exhaust guides, should be fouling spark plugs. If rings are gummed up from lack of maintenance, running it with clean oil may clean them up and improve ring seal. Or someone changed IC and its got half a million miles! LOL I would still pull valve covers and look

 

[alpinecrick]

Thats an engine thats never had an oil change.
I suspect you have multiple issues to go through that much oil.
Part of it is going past crispy fried valve stem seals and getting burnt.
Some of it is going through the pcv and back into the throttle body and getting diluted and burnt.
Some of it is getting vacuumed up and blown into the exhaust.
And some might be going out the rear main seal.
But thats also assuming the pcv is hooked up.
Pull the plugs although im sure they are all pretty nasty.
But even with all that considered, thats a lot of oil.
look it over underneath front to back and look at the tailgate.
sometimes you can get a leak that kinda just mists everything with oil.
Hate to tell you this, but that is pretty awfull compression for 140k.
I think its never been maintained.
But do a leakdown test before you condemn it.
compression is only part of the story.
good luck

This.........

 

[Erin]

When mine had bad valve seals it smoked like a chimney. And it had a cat.

 

[Wozny]

Thanks for all these great ideas, I wrote them all down and will check all of them out. I’ll check tailpipe and do a leak down test, etc. I’ve been meaning to get a leak down test anyway. If the rings turn out to be OK I might just do a valve job, but I’ve heard that might start oil going my the rings from increased compression, any opinions on that?
I have put big long cardboard under it during and hours after running it without a drop of oil leaking. Which is really hard to believe because I didn’t bring this up before, but there was one time about 300 miles ago when I had driven it 200, when I stopped along the highway after going fast down a pass, looked underneath and saw oil dripping fast all around underneath that engine. It was dripping from a dozen different places and fast. But it never has done that since. I’ve checked the fittings on the oil cooler lines well and nothing there or anywhere now, not even when I stop quick on the highway. I’ve checked the PCV but not the drain back holes or rings yet. I didn’t know the cat could stop smoke so that was an eye opener. I sure do appreciate all your great information. I’ll let you know what I find out with all those checks.

 

[Wozny]

When mine had bad valve seals it smoked like a chimney. And it had a cat.

When mine had bad valve seals it smoked like a chimney. And it had a cat.

That’s very good to know, it sure seems like it ought to be leaking, but I’ve put cardboard under it a lot without any sign at all. It was dripping a very little a few months ago but not now. Thanks much

 

[RawbDidIt]

Thanks for all these great ideas, I wrote them all down and will check all of them out. I’ll check tailpipe and do a leak down test, etc. I’ve been meaning to get a leak down test anyway. If the rings turn out to be OK I might just do a valve job, but I’ve heard that might start oil going my the rings from increased compression, any opinions on that?
I have put big long cardboard under it during and hours after running it without a drop of oil leaking. Which is really hard to believe because I didn’t bring this up before, but there was one time about 300 miles ago when I had driven it 200, when I stopped along the highway after going fast down a pass, looked underneath and saw oil dripping fast all around underneath that engine. It was dripping from a dozen different places and fast. But it never has done that since. I’ve checked the fittings on the oil cooler lines well and nothing there or anywhere now, not even when I stop quick on the highway. I’ve checked the PCV but not the drain back holes or rings yet. I didn’t know the cat could stop smoke so that was an eye opener. I sure do appreciate all your great information. I’ll let you know what I find out with all those checks.

May be worth replacing some gaskets while you're at it. If it was leaking from several places like you say, sounds like it may be the oil pan gasket may have been a bit dry from a while of sitting around (presumably with no oil) and then swelled up a bit with fresh oil and use. Not an unheard of phenomenon with cork gaskets, but they tend to fail pretty spectacularly shortly after.

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[Wozny]

Thats why the leakdown test is important. The oil in the rings trick can tell you if its blowing past the rings or going out the valves.
The best test is back off the rockers and put the oil in and listen to where the air is going.
It might be smoked. but, if its just an extreme oil leak. I would drive that thing till the rods came out of it.
Ive seen worse

Thanks, I’ll take the covers off, it’ll be interesting to see how much sludge is there anyway. So if I pour oil onto the valves I’ll be able to tell if it’s going past the seals by listening?