My vote is valve stem seals. Ken Bogart ----------------------------------------------------- 96 Montego Blue FFS Coldside (His) 97 Black & Tan (Hers) 90 Crystal White (sons) ------------------------------------------------------ http://www.miatacare.com http://www.cincimiata.com http://www.bcchallenger.org MiataMail.com list owner
On Sun, Apr 10, 2011 at 12:20 PM, <[email protected]> wrote: > At 200K, especially if the engine has been turboed, one might expect that > some things, including the head gasket, have suffered some wear. > Have you checked the radiator or the coolant expansion tank for air bubbles > and/or oily film, which would indicate that exhaust is blowing by the gasket > somewhere and entering the coolant system? > > Another possibility, if the smoke is not too heavy or not affected by > pressing the accelerator, would be oil leakage from behind the head or at > the CAS o-ring, running down the back or side of the engine and getting onto > the exhaust pipes. That oil would burn and smoke for a while until gone, > then disappear. > > *However*, at 200K, overnight leakage at the valve seals into the > combustion chamber could also be the reason you're getting smoke upon > start-up that disappears after warm-up (running burns up the leakage, and > the smoke disappears). This could be the symptom that starts you thinking > about a rebuild or a replacement engine, and is my best guess without any > sort of visual inspection... Good luck with it, the leak down test should > prove valuable. > > Jerry aka LGO > > > > -----Original Message----- > From: Chad J. Douglas <[email protected]> > To: [email protected] <[email protected]> > Cc: Ken Riley <[email protected]> > Sent: Sun, Apr 10, 2011 11:23 am > Subject: Head Gasket? > > 1997 STO - - 200k k miles > > Sometimes when you start it up from cold, it smokes like a freight train > for 20 minutes (although, I can’t remember the last time I saw freight train > that “smoked like a freight train.”) Sometimes, just a few minutes. > Sometimes a puff. Sometimes nothing at all. > > Once the engine is warmed up, no smoke at all. I tested it in high vacuum > to check for valve seals, and even under high vacuum (revved 1st gear to > redline, took foot off gas for 2-3 seconds, then back on) I get NO smoke. > Engine runs GREAT. No strange behaviors except for the smoke. Even when > it’s smoking - runs very well…. > > Engine has no appreciable blow-by – you can take the oil cap off when the > engine is cold and there’s just the normal amount of crankcase pressure > there. > > So, I’ve come to this idea: there is a small crack in the head gasket > between one or more cylinders and the pressurized oil passageway. While the > engine is cold, oil can leak through, but then it seals up when warm. Not > sure what would explain the varying “smoke times.” > > Any ideas on what to check next? I recently purchased a leakdown tester > from Harbor Fright (pun intended), but I’ve never used one. It seems that > leakdown is a good next step…so….anyone want to tell me how to use one of > these things? > = > > _______________________________________________ > Miatapower mailing > [email protected]http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower > > = > _______________________________________________ > Miatapower mailing list > [email protected] > http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower > >
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