need diagnostic help

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need diagnostic help - 1/4/2008 10:17:35 PM    rolomac Posts: 119 Joined: 7/17/2005 Status: offline My '92 B2600i is sick.  When starting it up cold it starts easily but only hits on 3 cylinders for about ten seconds or so and then smooths out but is showing a lot of oil in the exhaust.  It varies but can be really alarming at times - huge clouds - but then after driving for a bit it clears up.  Strangely, it isn't showing a lot of oil consumption.  My thinking - which a mechanic friend agrees with - is that I have a leaking valve stem guide seal which is allowing a small amount of oil to drain down into the cylinder.  The oil is fouling the plug in that cylinder and keeps it from firing until it burns off, putting out the cloud of smoke.  I've been told that a very small amount of oil can cause a big oil smoke cloud.  So - - - I'm wondering if anybody else has encountered this and can confirm my thinking or suggest another answer.  Has me kind of spooked because a new cylinder head with valves is over $700 and lots of labor.  It's a good truck that I like a lot but is it worth it?  Any other possible solutions?  I'll appreciate any help or suggestions.  Rolomac Post #: 1

RE: need diagnostic help - 1/6/2008 1:21:37 AM    supratreo   Posts: 35 Joined: 10/7/2007 Status: offline sounds like you need new valve seals but why are you looking for a new head? (in reply to rolomac) Post #: 2

RE: need diagnostic help - 1/6/2008 2:44:30 PM    rolomac Posts: 119 Joined: 7/17/2005 Status: offline I'm not a "hot wrench" myself - don't have the time, tools or talent to do anything more extensive than oil changes and so on.  At this point I'm looking at options.  I was told that a valve seal job it pretty labor intensive on a 16 valve head and it might be better to look into a new or remanufactured head.  That's kind of why I'm tossing it out for discussion here - to learn from you other guys.  So tell me - can valve seals be replaced without pulling the head?  Is it really that bad of a job? Thanks for helping. Rolomac   (in reply to supratreo) Post #: 3

RE: need diagnostic help - 1/7/2008 12:43:58 AM    supratreo   Posts: 35 Joined: 10/7/2007 Status: offline there is no way a valve seal job is harder than replacing a head. it is a little bit of work but replacing the head is even more work and a waste of money if theres nothing wrong with it. (in reply to rolomac) Post #: 4

RE: need diagnostic help - 1/7/2008 5:35:54 AM    sstlaure   Posts: 2364 Joined: 11/28/2005 Status: offline Pulling a head on a 4-cylinder isn't usually all that bad as everything is right on top of the motor.  I'd get yourself a manual and a few tool (you won't need that many to remove the head) and take the head to a local shop.  Buy the various parts yourself to avoid mark-up and just have the guy assemble them.  You'll need new head gaskets and while i had the head off I'd get it decked (machining of the surface of the head that mates to the block.) This will ensure a good seal when you reinstall the head.  You'll also get a small increase in compression ratio due to the lower deck height of the head (more power). It can get very expensive when you have someone else doing the job.  You'd be at $700 buying a new head and you still would have to pay someone to pull the old one and reinstall the new one. _____________________________ 2004 Mazda6 Sportwagon Any statements made are purely my opinion (in reply to supratreo) Post #: 5

RE: need diagnostic help - 1/7/2008 7:50:20 PM    supratreo   Posts: 35 Joined: 10/7/2007 Status: offline ya but why would you pull the head to do the valve seals? you just need to get rid of the cam and rockers and your pretty much there. add some compressed air to the cylinder to hold the valves up, pop the springs out and replace the seals. (in reply to sstlaure) Post #: 6

RE: need diagnostic help - 1/8/2008 5:05:29 AM    sstlaure   Posts: 2364 Joined: 11/28/2005 Status: offline True enough Supertreo, although then you have to have a source of compressed air and do 1 cylinder at a time (unless you make an octopus to feed air through every spark plug hole at the same time. < Message edited by sstlaure -- 1/8/2008 5:06:50 AM > _____________________________ 2004 Mazda6 Sportwagon Any statements made are purely my opinion (in reply to supratreo) Post #: 7

RE: need diagnostic help - 1/8/2008 6:12:53 PM    supratreo   Posts: 35 Joined: 10/7/2007 Status: offline you can work one cylinder at a time. as long as the springs and keepers are in, your valves won't go anywhere. (in reply to sstlaure) Post #: 8

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