Ways to diagnose rings as source of oil consumption

[Belgian1979]

Well, if you're convinced it's ring seal, there's only one option and that is to take it apart, rehone and new rings. Keep us informed.

No, I'm not convinced about anything. Sorry if I gave you that impression. That's why I posted this and want to discuss. The last thing I want it to be is rings because that's the most work to fix. It's just that I think I'm out of other things it can be, so I posted here for opinions and others experience. I hope it turns out not to be rings.

try out the map sensor and see if you get huge swings in crankcase vacuum under heavy decel. It will confirm the rings.

[1972ho]

Take it over to a chassis dyno and do full rpm loads on the engine and see if it seals up.May be just driving it on the street may not be getting the job done.

[zwede]

try out the map sensor and see if you get huge swings in crankcase vacuum under heavy decel. It will confirm the rings.

Would it though? The compression rings are fine so I don't think I'd see anything?

[zwede]

Take it over to a chassis dyno and do full rpm loads on the engine and see if it seals up.May be just driving it on the street may not be getting the job done.

Also a thought. I've been meaning to take it out on the highway and do longer WOT pulls in high gear but finding a highway that is not bumper-to-bumper has proven difficult... maybe better to take it to a dyno.

[Belgian1979]

try out the map sensor and see if you get huge swings in crankcase vacuum under heavy decel. It will confirm the rings.

Would it though? The compression rings are fine so I don't think I'd see anything?

I think so, on decel it's mostly the oil control rings and specifically the second ring that controls what goes up.

[shoedoos]

any chance there's a low tension oil ring in there?

[zwede]

any chance there's a low tension oil ring in there?

Should be standard tension. They're sealed power R9590 45. I can only find the R9590 35 on summit but I think the only diff is they're 030 over and mine 040. Summit lists them as 5/64 rings with 3/16 std tension oil rings.

[Newold1]

I know it sometimes very hard to believe a somewhat lower mile engine has to go back down for something like this but Guys, LOOK AT THOSE PICS OF THE BORE WALLS AND ALL THOSE VERTICAL SCORING! That is not going to go away with dyno pulls or highway blast driving! It's not right and needs to be properly fixed. The things that are causing this engine to consume moderate amounts of oil will not fix themselves. One last touchy question. You are running a good air cleaner on this engine and that damage could not be from dirt or sand ingestion?

[zwede]

It could be sand. The car was wrecked (rear ended) in 2009 and I and another guy did a full body resto on it over at his shop. It has an L88 hood so the filter is in the hood, which was off the car for a year or so. We were pretty careful and had a plastic bag over the air cleaner base but I wasn't there 24/7 so... but I also want to say I saw oil on the plugs before 2009... heck, too long ago, can't remember.

[Dan Timberlake]

Hi zwede, Did you clean the cylinders before assembly?

[Newold1]

Ah HA! No air cleaner and sand, that could explain those scratches. Dirt of almost any kind and nice smooth well finished cylinder bores and good rings don't fair well with dirt! Please don't put good money labor and parts in a nice engine build and then run it without a good air cleaner !! Air cleaners are always less expensive than a costly redo on an engine. I'm done now!

[zwede]

Hi zwede, Did you clean the cylinders before assembly?

I did.

[zwede]

Ah HA! No air cleaner and sand, that could explain those scratches. Dirt of almost any kind and nice smooth well finished cylinder bores and good rings don't fair well with dirt! Please don't put good money labor and parts in a nice engine build and then run it without a good air cleaner !! Air cleaners are always less expensive than a costly redo on an engine. I'm done now!

Thanks for a good thread. The possibility of dirt getting in while we worked on the body didn't occur to me, but makes sense. Hopefully someone will look at this thread in the future and take precautions before they have body work done.

My lesson learned is that I should have bought a cheap 14" air cleaner and bolted it on while the hood was off the car.

[MadBill]

O/T, but many years ago I had a 4th-hand Morgan Plus Four sports car. It had no air cleaner when I bought it and the bonnet was such a close fit I couldn't figger where one would go. Decades later at an import car show I saw an immaculate example and asked the owner if I could see the air filter assembly. "Ha, no chance; the factory never fitted one!"

[Tom Walker]

If it is just a weekend toy, one option would be just to enjoy the car as is. Pulling the engine out again, especially a Corvette with the fragile body panels, has potential for body and paint damage. Your call though, good luck with what ever you choose to do.