OK, this is on the engine in my pick-up, so performance isn't a huge concern here, I'd just like to find the cheapest way to effectively fix this. Rebuilt engine, about 2500 miles on it now. It has true dual exhaust and is only smoking (blue=oil)out one side. It's been doing it for about 2000 miles now and is getting worse by the mile. I haven't actually pulled out the sparkies to investigate, or done a compression test, but I'm fairly confident that I know what the problem is. There was a nick in the side of one of the pistons, occurred at the machine shop when putting the piston on the rod. I knew I shouldn't have used it, but I was in a hurry and used it anyway. So I'm betting that one of the cylinder walls is torn all to ****. I don't want to have to get a new block or bore this one out to .040 (it is already at .030)b/c that will cost a lot of money for the machinework and new pistons. And I don't want to get a new block either. So I had a few cheap-fix ideas: #1 bore out the ruined cylinder to .040 and get a new piston. Leave the rest at .030. I'll get the piston and rod weight matched to the rest so the engine won't be off-balance. How much difference will .2 ci in one cylinder make? #2 Can I get a sleeve put in that one cylinder? How much will that cost? These are my only two ideas. What do you guys think? Suggestions, please!

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91 Z28
Come see The Vicious...

 

The piston is aluminum, the cylinder wall is iron. A nick in the piston itself won't damage the cylinder walls.

More likely, either an oil scraper ring got damaged during installation, by popping out of the ring compressor before it was all the way in, and it got bent, or damaged the ring land, so that it sticks; or, it has a damaged valve guide or seal. My gut instinct is the second thing.

In any case I would strongly recommend against boring one cylinder, but as far as making the engine run wrong, it won't cause a problem there. It's just a real ghetto approach to things that makes any future maintenance that much harder. Also, I'd suggest looking at the valve guide seals on the offending side first before getting excited about the bottom end.

One other cause of mystery smoke is the intake gasket. Remeber that the bottom of the intake ports is adjacent to the crankcase; so if the gasket is damaged there, it will suck in oil. If the engine runs like it has a vacuum leak but you can't find one, and has mystery smoke besides, then that's another good cheap place to try a quick fix.

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"So many Mustangs, so little time..."
ICON Motorsports

[This message has been edited by RB83L69 (edited September 25, 2001).]

 

You can pop out one cylinder to 40-over and leave the rest alone. Did it once. Worked just fine.

I agree with RB, though, that may not be the problem. Wouldn't it be nice to find out the intake gasket didn't seal up on one of the ports and you were just drawing oil vapors out of the lifter valley?

 

Sure would be nice if it wasn't in the bottom end. I can only hope. As for the nick in the piston, it was more like it got pinched when it was hot or something. It was right by one of the ring lands, the second compression ring. The metal was smashed into the ring land a little, and the ring wouldn't rotate b/c it was too tight. I used a file to widen the land back out so the ring fit OK. What do you think?
As for compression testing, if I find a bad cylinder, I should squirt a little oil in the cylinder and try it again. If the compression goes up then the problem is in the rings/cylinder wall, right? Will I lose a significant amount of compression if one of the guides is screwed up? I figured if it was a valve guide or seal that it would smoke more at startup than when running, and this is not the case. How can I check that intake leak? Spray the base with propane and see if the idle changes?

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91 Z28
Come see The Vicious...