Burns oil when cold

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Dana67Dart

Dana67Dart

The parts you don't add don't cause you no trouble
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67 273, 2bbl, 319,000 miles, engine rebuilt about 100,000 miles ago in the 80's

Coolant level consistent, oil drops over time, (leaks like a 54 year old engine... rear main, valve cover, oil plug)

When I start it up no smoke, (typical start up routine... pump 2 to 4 times depending on when it was last driven, crank, stop, crank, start, feather gas a little, neutral for about 10 seconds, reverse, back out of driveway, feather gas a bit, put it in drive and it will run flawlessly from then on out) drive it 400 feet to the major road, turn and accelerate moderately. Light cloud of smoke (light grey, blueish tint, might be too much choke? ) enough that I can see where I have been. Drive it for 5 minutes or so and not another visible hint of smoke.
Have not looked at the plugs for oil buildup, or done any other diagnostics yet.

Thoughts?
 
Sounds like it's taking a little time before the oil gets hot enough to burn and create smoke. Like some oil is getting in the exhaust manifold and when you accelerate onto the main road it's pumping enough heat into the manifold to burn it? Maybe check the plugs for oil residue?
 
Valve seals dried out and cracked off the stems. Oil is draining down while it sits into the manifold/exhaust ports. Spark plugs all out, stuff some rope in the spark plug hole, bring the piston up to hold the rope/valves up, compress the spring, remove the keepers and replace the seal on both intake and exhaust valve stems. Reinstall parts, lower piston and pull out rope. Repeat 7 more times.
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I was thinking seals too. My dad's favorite, The Rope Trick! I guess it is time to take off the valve covers and have a look.
 
If you suspect valve seals, you should be able to let it idle 3-5 minutes and blip the throttle, it should puff smoke. Vacuum is the highest at idle and will pull oil by the intake valves if the seals are bad or guides worn out. If you do replace the seals , you only need to replace the 8 intakes. Hell you don't even need them on the exhaust.
 
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How much does it actually "use?" If it's not loading up the bumper/ rear of car with oil I'd RUN it
 
Kendog 170 said:
1st I've heard of the rope trick. I always used Compressed air. I like it.
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Best part of rope trick. It is impossible to drop a valve in the cyl.

And you do not have to compress the rope very much. I would use cotton rope incase some comes off in the cyl.
 
67Dart273 said:
How much does it actually "use?" If it's not loading up the bumper/ rear of car with oil I'd RUN it
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Between leaks and burn? It is down 2 to 4 quarts per year, driven 1000 to 2000 miles per year.

No noticable marks yet. I need to adjust the valves anyway so I'll have a look then
 
It’s more likely the piston rings. If it was valve seals you would see smoke right at start up, because the oil leaks off the heads and through the seats after shut down. Which leaves oil in the chambers for start up. Typically smoke from a valve seal leaks goes away as the engine warms up. You also don’t see much oil loss from valve seal leaks, since it’s an intermittent oil to the top anyway.

Weak rings, on the other hand, wouldn’t leak immediately on start up because there isn’t a ton of oil being thrown around and nothing in the chambers to start. But as you get going the oil pressure rises, oil gets slung around more and the load on the engine pushes it past the rings. Then as the engine gets up to temp the rings expand a bit and reduce the leakage. At that kind of mileage I’d expect the rings to be pretty tired.

The smoke after turning would indicate rings too, you turn, slosh the oil in the pan to on side and up the walls, and the rings can’t seal it out of the cylinders.
 
I agree. If you stop engine like going to the store then start it and get a big puff of blue smoke I would say valve seals. Rings? Put some engine restore in it and see if it helps buy you some more time. Maybe go a grade thicker oil too.
 
Dana, I would lean a little more to the rings getting weak. Valve seals would show more smoke on deceleration.
 
In my dad's log book:

In 1983 205,410 miles engine was rebuilt.
In 1998 310,928 miles the heads were pulled looking for what turned out to be a timing cover leak, mechanic stated "the rings look barely seated" "the crosshatch is still in the cylinders."
now 2021 319,000 (only 9000 miles in 23 years) burning a little oil when cold. Dad was a firm believer in AMS oil and even had the bypass filter add on at one time.

wondering if the rings really have never seated properly?

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Dana67Dart said:
In my dad's log book:

In 1983 205,410 miles engine was rebuilt.
In 1998 310,928 miles the heads were pulled looking for what turned out to be a timing cover leak, mechanic stated "the rings look barely seated" "the crosshatch is still in the cylinders."
now 2021 319,000 (only 9000 miles in 23 years) burning a little oil when cold. Dad was a firm believer in AMS oil and even had the bypass filter add on at one time.

wondering if the rings really have never seated properly?

View attachment 1715684939
Click to expand...

Could possibly be the rings but just because the cylinders still have crosshatch doesn't mean the rings aren't seated, crack open any high-mileage Magnum or G3 Hemi that was maintained decently and there will still be crosshatch on the bores.

Replacing valve seals is easy enough but I'd also try a compression or leakdown test (preferably leakdown), if that all checks out good and replacing the intake valve stem seals doesn't fix the smoke I'd say hell with it and just drive it lol. 2 quarts per 1000 miles is a lot but since you drive it so little I wouldn't worry about it.

The 5.9 Magnum (with roller cam) in my Duster consumes a little over a quart every 1000 miles, I have noticed when I had the intake off to re-seal it the intake valves were oily so may not have had seals installed (Edelbrock heads were ported, machined and assembled by a Atlas Performance in Loveland). I'm also running Valvoline 5W-40 MST oil which is meant for European diesels but I think it's too thin when cold and getting past the rings and valves during warmup or when sitting cooling down after a drive. Next oil change I'm switching back to either Penn Grade or Shaeffer's 10W-40. Not to mention the fact I have external oiling for the rockers (LA-based heads on late Magnum block) might be sending too much oil to the top end, another thing I've been meaning to check.

Could always buy or borrow a bore-scope and look down the intake next time before you go to start it up, see if the intake valves are oily. Then you know for sure the valve seals are bad or at least oil is seeping down through the guides somehow.
 
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