So I finally got my engine out and the heads off, and everything is remarkably clean, not a spot of carbon anywhere. The head gaskets looked new so I know they've been off recently.

This car had so much blowby that when you unhooked the hose that went into the TB it looked like the car was on fire. After taking the heads off (The valves look new, too) I can't imagine why. there is very little ring ridge, can barely feel it. You can still see the swirl marks from when they machine the piston ontop.

My question is, is it possible they could have installed the rings upside down? (I haven't pulled the pistons yet, that will be today or tomorrow) I've just never seen an engine with such a huge amount of blowby, and look like it was rebuild a few thousand miles ago. There is a small bit of piston play, but it's my understanding these pistons expand when they get hot.

Also, these pistons have an "8" and an arrow stamped ontop, is this a factory stamping? If needed I can upload a pick of the top of the piston but I'm sure you guys have seen them.

 

Would not be the first time some one put the rings upside down. I once got a very nice corvette for a guy because it smoke so much he didn't want to drive it. Pulled the motor and the second ring was in upside down. Barrel honed it and a new set of rings and made a lot of $$$$ on that deal.

 

If you you can catch your fingernail on the ridge, then it's too much, but the way you describe it, it should be fine. Very possible the rings were installed upside down, but unlikely. Most piston rings any more have engraved "this side up" or "this side down" on it or a "dot" to signify that side should be up.

It's normal for there to be a little play and you can usually tell when it's too much. I don't remember mine having a "8" on top, but it's been a while since she's been torn apart. Pics are always nice, chances though is it's a stock flat top with valve reliefs.

 

Could be the engine wasn't broken in properly, and the rings never seated right.
Note: do not break in the engine in the garage, you want to drive the car so that the rings are under a load. Being under a load is what pushes the rings out against the cylinder walls, they don't seal by the (slight) spring tension of the rings themselves.

 

Sometimes beginners don't get that bottom oil ring together properly. It is the three piece one on the bottom of the piston.

 

Chyea

 

Oiling rings should have any effect on blow by. Most of the time when I get an engine that was "rebuilt" that has hvy blow it ends up being the fact the cylinders are too far out of round for the rings to comp for. Rings are designed to handle about .005 or out of round. You can get away to .008 or so. It is not uncommon to see .015" out of round on a high miles motors. In many cars the blow by gets worse after the new rings are installed because the old rings formed to the out of round condition. It could take 20,000 miles for the new rings to wear in like the old ones did.

If the motor was recently Re-ringed then a ridge reamer and hone would make the wear undetectable by vision or feel. Also the wear is heavest at the lower part of the cylinders.

 

better have the valve guides done.

 

I have seen and experienced this exact scenario. Engine was re-ringed but they didn't measure the bores for out of round. When I finally got the time chance to get into it, I had to bore it .030 and do a complete rebuild to correct the blow-by.

I have also seen the compression rings installed upside down.

The oil ring should have nothing to do with blow-by. They are there to scrape excess oil off the cylinder walls else it will work past the compression rings and cause excessive smoke.

 

Thanks for the feedback. As far as having the valve guides done, there isn't smoke out the exhaust, it's out the crankcase.

The motor has 140k on it, and there isn't a spec of carbon build up ANYWHERE. Something is fishy.

I can't get my engine stand peices all in one spot so I haven't pulled the pistons yet, but the walls are silky smooth. I know the heads have been off, it had new FelPro gaskets, (and I can tell where they scraped off the old gasket).

What's the best way to tell if the cylinders are out of round? Is it possible they didn't hone the cylinders at all and the new rings didn't seat (if in fact they did attempt to re-ring it?). Will it cause this amount of blow-by if the rings weren't properly seated or broke in?

Personally I just can't get over how clean everything is for supposedly having 140k miles on it. There is literally no carbon buildup anywhere, not even the exhaust valves, and the valve springs look almost new. It's unlike any higher mileage engine I've ever tore down.

I'm trying real hard not to have to send the block off to the machine shop, I plan on selling the car once i get it running right again, but after machining I'd be lucky to get out of it what I have in it.