blackeg

curiosity is getting the best of me, so im wondering what would cause oil control rings to fail or allow oil to pass by? detonation? cylinder out of round? wouldnt those conditions effect all the rings and result in lower compression and increased leakdown from the top and 2nd ring?

let the discussion begin...

Muckman

iTrader: (2)

Did you check the gap of the oil rings?

blackeg

here's all the specs from when i put the shortblock together last year. #4 is the one in question that has oil on the piston. the only specs i see for oil rings are at least .015 which mine are. thats what they turned out to be right out of the box, ungapped as you are not supposed to file them. they are cp rings for the record. just trying to get a discussion going maybe some good info will come to light and be able to help someone else in the future. sorry for my poor handwriting, especially from a teacher. thank god for powerpoint lol

OneBadTurboCRV

No real discussion to be had. The oil control rings are to wipe EXCESS oil off the cylinder walls. They in fact, do NOT wipe off ALL the oil.

http://en.m.wikipedia.org/wiki/Piston_ring

There is not much too them... and since they are cooled by oil their gap doesn't matter like the top 2 rings do (as long as you hit the minimum or course). They only expand as much as the oil/skirt/cylinder walls heat up.

PS - You have very bad grammar and writing for a Teacher. You are correct on that one Sir.

rclark

I'm going to go out on a limb here and assume he' s a shop teacher like me. If that's the case, it is the content and hands on skills that really matter. And yes, thank god for power point and CDX...

As far as oil rings go, I always assumed detonation would be harsher on them as opposed to the compression rings dive to the way they are constructed and the location towards the middle of the piston, though I have no science to back up that assertation. I'll be interested to hear what other more experienced folks have to say on the subject.

As far as your motor goes, how are you sure it's an oil control ring issue?

DarryCar

In my limited experience, the oil scraper rings are very brittle. Most all of the oil rings that I have seen fail are due to improper instillation. It is very easy to expand/over stretch those rings and give them just enough of a crack or imperfection for them to break later once the engine is running. I am curious as to when you noticed the failure. How many miles did you put on the engine. What was your first sign. Sure it is a PITA to pull the bottom end and replace 1 oil ring, but in retrospect at least you didn't kill the motor. Just make sure that is the actual problem before you go tearing the motor apart.

Runnerdown

Lets look at a couple things.

Quoted from CP:

SECOND RING
The second ring is a cast iron with a taper underhook groove face.
The THG ring acts as a wiper and pushes the oil back away from
combustion.This type of ring allows you to run a lower tension oil
ring.

Cast iron is strong but brittle in this case, treat them like glass. Its also directional, so be sure the correct side faces up. Very easy to chip or break them upon installation into the cylinder or on the piston. Also, the lower oil rings are easy to bend and damage by hitting them against the cylinder ledge. I have seen these mistakes made many times.

Due to the delicate nature and critical function, I purchase a bore specific tapered ring compressor for each engine I assemble. ARP, Wiseco and others have them available for reasonable pricing.

blackeg

close, science teacher. most of my friends are shop teachers. i can write in proper english when i want to. i do not feel that it matters here especially considering how poor most other people type and spell.

i have great leakdown and compression, so that should rule out my top ring being the culprit
i just replaced the valve seals and do not have oil buildup on the tops of the valves. (im going to take the mani off today again and double check.) if that verifies then its not seals or guides. i dont think hg, im not consuming, burning or over pressurizing the overflow or coolant system. only things left are 2nd and oil rings...


runnerdown, you are on the right track. at this point im expecting to see some damage to the oil ring perhaps from installation or that im a dumbass, should stop working on cars late and night and put the 2nd ring in upside down.

here's a link to a vid at the valley last year. (bad clutch caused slow shifts). you can see it has a little smoke. its slowly been getting worse, about 2x as much. the vid is on the same build though, so the rings have not been replaced since.
http://photosbyjim.smugmug.com/Compe...HR5NJ&lb=1&s=A

blackeg

well, here are more pics of today's work.

here is the exhaust port. bone dry with more black carbon buildup compared to the whiter colored valves in my other cyls.


turbine housing. bone dry no leaking oil anywhere


crankcase ventilation setup. this is new for this year, as opposed to the back of the block vents that i used to use. in 600 miles ive gotten barely any oil out of it.



here's how im feeling currently

lol i was absent from work for a day the other week and this is what the class did with the substitute in the room. i have a fun group this year