Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84 exptools; site ihu1g.UUCP Path: utzoo!watmath!clyde!cbosgd!ihnp4!ihu1g!rls From: rls@ihu1g.UUCP (r.l. schieve) Newsgroups: net.auto.tech Subject: Re: causes of blue smoke: ring wear vs. valve seal wear Message-ID: <728@ihu1g.UUCP> Date: Mon, 11-Nov-85 09:01:31 EST Article-I.D.: ihu1g.728 Posted: Mon Nov 11 09:01:31 1985 Date-Received: Tue, 12-Nov-85 04:25:44 EST References: <1278@ihuxi.UUCP> <318@watmum.UUCP> Distribution: net Organization: AT&T Bell Laboratories Lines: 41 > Many, many people have posted articles to the effect that blue smoke > on closing the throttle is a symptom of valve-guide wear, not ring > wear. I think these statements are misleading. > > In my experience, the symptoms are exactly consistent with ring wear. ......... > I have not conducted a statistically valid survey (I am sure the other > posters have not, either), but in my experience high oil consumption > is almost ALWAYS caused by ring wear and almost NEVER caused by valve > wear (5-0 on cars I have actually repaired). ................ > I won't argue too strongly against replacing both the rings and the > valve guides, but I think it is holding out false hope to suggest > that fixing the valves alone is likely to cure heavy oil consumption. ............ One confusing part of the above article is whether valve guide wear or valve seal wear is being discussed. My own experiences, working with cars that are reasonably maintained, (oil changed regularly) is that rings are almost never the problem but valve SEALS very often are. Whenever my 1971 GTO started going through more than 1 quart of oil in 1000 miles, I knew it was time to replace the valve seals. One time I took the heads off thinking the valve guides were bad causing the seals to self destruct. The shop asked me why I bothered to bring the heads in as the valves were fine, just new seals needed. They recommended teflon seals for replacements. My 1980 Turbo Mustang, used to go through valve seals constantly due to the higher engine temperatures. The seals got brittle and cracked. The second set went bad so quickly that I let a mechanic convince me I had a cracked ring and I didn't recheck to valve seals until I had the engine disassembled. No cracked piston rings, but lots of cracked valve seals, and lots of cussing at the mechanic. The engine didn't even burn the oil, it got right past the seals directly into the exhaust manifold. 3 out of 4 exhaust port were wet with oil. My advice, try the valve seals first!!!!! Rick Schieve ...ihnp4!ihu1g!rls