HICKL Posted January 8, 2004 Share Posted January 8, 2004 My car will sometimes blow some smoke when I let off and get back into it (like between 2nd and 3rd gear), but it doesn't seem to do it under load. I have aluminum valve covers with no baffles in them. Can the vacuum hose going to the pcv valve suck oil or oil mist back into the carb enough to generate a puff of smoke? Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted January 8, 2004 Share Posted January 8, 2004 If your covers don't have holes...Where do you have the PVC?? Rufus Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 8, 2004 Share Posted January 8, 2004 I think he's saying that it has holes, but no baffles. I'd suspect the piston rings first though. When you decel, it draws a lot of oil onto the cylinder walls. If the oil rings can't scrape it off... smoke. New engine? Old? What's the story with the engine? Jon Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted January 8, 2004 Share Posted January 8, 2004 oops.. It does say baffles...What J said....bad rings=blowby=smoke. How old is the motor? Try a compression test. Rufus Quote Link to comment Share on other sites More sharing options...
SpeedRacer Posted January 9, 2004 Share Posted January 9, 2004 It could be oil through the PVC and adding a baffle would be a good start. However, when an engine puffs blue (not black) smoke after high vacuum it's usually not the rings but the valve seals. If you can, coast down a long hill with the throttle closed and then get on it at the bottom. If you get a lot of blue smoke then I would have the valve seals and guides checked. Quote Link to comment Share on other sites More sharing options...
denny411 Posted January 9, 2004 Share Posted January 9, 2004 You should be able to see oil in the pcv hose if it indeed has been sucking oil. Quote Link to comment Share on other sites More sharing options...
HICKL Posted January 9, 2004 Author Share Posted January 9, 2004 motor only had about 2000 miles on it. Compression was a little low on some cylinders (135 ish) I pulled the motor out and went thru it and everything looked good. The rings had an even wear pattern and everything. I went ahead and re-honed it and put new rings again. Just put motor back in last night. The pcv hose would be a little oily, not dripping or anything. I know I was getting some blowby the rings because if I squirted a little oil on the top of the piston the compression would come up to 155. I hope it's right this time. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted January 9, 2004 Share Posted January 9, 2004 Give the rings a chance to seat themselves. Tim Quote Link to comment Share on other sites More sharing options...
HICKL Posted January 9, 2004 Author Share Posted January 9, 2004 How long would you expect it to take for them to get fully seated. They are not chrome or anything special like that. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted January 9, 2004 Share Posted January 9, 2004 If you 'lubed' the bores, it will take the rings longer to seat. If you assembled them 'dry', then 500 miles should be plenty. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 9, 2004 Share Posted January 9, 2004 Make sure you keep doing what you were doing, though. Don't drive at one speed because you don't want it to smoke. Take it up and down in rpms, let it engine brake. Jon Quote Link to comment Share on other sites More sharing options...
hjc74260Z Posted January 12, 2004 Share Posted January 12, 2004 I'd break the engine in before considering a tear down. You should definitely get some baffled valve covers though. There is so much oil flying around inside the valve covers that it is bound to get sucked into the PCV. That is why OEMs use them. Ring blow-by just increases the flow rate through the PVC and will aggravate the situation. I had some baffle-less M/T covers on my 350 and it sucked a lot of oil on a fresh rebuild. It did not improve until I finally installed a set of aluminum Z/28 covers with baffles. Quote Link to comment Share on other sites More sharing options...
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