I have personally rebuilt about 15 engines with high mileage that were burning lots of oil. My comment is that I have never seen worn rings, ever. I saw stuck, glued in rings from oil being overheated at that location. I suppose this is an arguement for synthetic oils. the problems were always caused by blown radiator hoses and dumb *** drivers that didnt stop.

I do have friends that religiously change oil, some as often as every 1000 miles and neglect their cooling systems and hoses. I think there is more to longevity of engines than over-frequent oil changes.

The only wear I ever saw was cam and lifter wear, in those years, chevy was known for cams that rubbed all the bumps off them, saw it many times. Engines were always squeaky clean inside too, I never saw any significant amount of sludge in any of em.

Ken

 

Oh boy does that bring back memories. I purchased a second hand Chevy p/u that drove me crazy trying to figure what was wrong with it. I remember going to the public library, pulling down a copy of a Chevy repair manual and it flopped open to a well worn section entitled "The Dreaded Chevy Camshaft Problem". It must have been divine providence because that was the cause. When I pulled that 'shaft' there was nothing that faintly resembled a cam lobe on it. That experience soured me forever on GM products. Thanks for reminding me why I am proudly Ford forever.

 

Well,
I have seen worn rings a number of times. The biggest sign of worn rings is a hone pattern still on the cylinder, but not all the way around. Rings that seal properly will wear that pattern completely off. And of coarse, a compression test will tell you that the rings are worn.

 

engine oil burning can have several causes
1. hardened cracked failed valve stem seals or poor design as in Chev V8's with the tiny square o ring that hardened, broke and pieces ended up in oil. intake valve head at stem would look like lump of black coal

2. worn valve guides or valve stems, common in older Ford V8's

3. failed PVC valve

4. Leaking gaskets or seals

5. worn rings, cylinder bores or pistons.
some older ring materials had a softer compression ring to slow bore wear. some block/insert liner material types are softer than others. chrome moly rings usually displace the slowest wear rates but increased bore wear rates. forged pistons have larger cyl wall clearance than cast pistons, forged are generally used in high horsepower high rpm apps where less friction is desired and oil consumption is not a worry but strength is.
look for worn ridge near top of cylinder at stop point of compression ring. some engines develop so much cylinder ridge that upon teardown the pistons cannot be driven out the top of the end, combustion ring hangs on the ridge, must be taken out the bottom.
measure cylinder for I.D. top, middle and bottom and every 45d around, cylinders can wear oval usually from crank offset- not center in direct parallel line of cylinder. pistons can also wear oval increasing oil consumption.
too wide or improperly positioned ring gaps.
oil breakdown/combustion products buildup in ring groves and plugging drain holes in oil ring.

6. worn crankshaft journals and bearings, more oil thrown onto cylinder walls overloading oil rings.

7. oil drain back restrictions in heads.

modern engines are fine with oil consumptions out the exhaust of 1 qt per 1k miles or less, some oil consumption in a modern engine is a good thing and indicates that pistons/ring/cylinders are not too tight with increased friction and decreased fuel mileage. valves do need some oil flow past them in a non diesel engine to decrease wear rate

 

This post is definitely a trip throug memory lane. I actually had a ford 390 t bitd that plugged up is valve area drainback holes. smoke beyond all belief, I think they saw it on weather satellites. I straightened out a clothes hanger and roto rootered the returns.

Of course, everything said previously is true, but stuck rings were the killer for my engines. when they were dug out, they had full tension and looked like they could be reinstalled.

Ken

 

i am always impressed with these new modern oils and engines and the small amount of oil they use up to 150k to 200k miles.
the engines of the 50's and 60's would barely make 50k to 75k before they would gobble the oil, of course who cared then, oil was $0.20 a qt and no EPA or emissions testing, even remember the cops Fords smoking, 56's that would blow smoke rings.

forgot the cylinder ridge reamer, got one out in the garage stored away in plastic bag and oiled, another techique for removing pistons out the top after reamer cutting the worn ridge out of the top of the cylinder. haven't used it in years.

 

not sure if I still have mine. been years since I had to tear down an engine that far. it might still be lurking somewhere in the "seldom used" tool bin.

 

I had a 454 big block and 25000 lb trailer turbo 400 trans. Had important job 100 miles and 4000 feet higher than Phoenix. 454 backfiring, spitting basically behaving poorly. this truck had to get there. did compression test discovered two wonky cylinders, no exhaust valve movement, no bumps on cam. Removed push rods from those two cylinders. instant conversion of 454 to 340. ran roughly but ok, felt just like two cylinders were missing, gee.

anyway that truck got there and back quite well on six cylinders before I was able to replace the cam. by the way, I replaced the cam with a crane super economy low rpm high torque model, a real baby cam, low lift low duration. It ran wonderfully, felt like a diesel gobs of torque.

true story