Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Blow By on a fresh rebuild. Possible ?? PLEASE HELP. Pics inside
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Old 09-23-2008, 11:10 AM
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j.d.brown.042964 j.d.brown.042964 is offline
406 Caprice:Rust Never Sleeps!
 
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I would agree that you should indeed fix the obvious problems first, and put some additional time on the engine (with a petroleum based oil) and then reevaluate. The oil on the stem of the valve could be from EITHER a bad stemseal, or excessive guide clearance, or some of both. Any excessive pressure getting past the rings and pressurizing the upper-end (thru the drainback passages) will only serve to exascerbate that type of an issue. Inspect valveguide clearances (comparitively, and against published specs.) and make repair{s} if needed, and inspect and/or replace valvestem seals as needed (best to do the whole set-it's cheap insurance). Change back to a good petroleum oil with zddp Then...check timing to be certain you're not getting pre-ignition (knock/ping) before continuing with your ongoing accumulation of running-time for seating the rings. (I mention timing/advance due to the fact that if you get too much pre-ignition you can break ring-lands and rings which will guarantee you an oil-drinker with unbalanced cylinder pressures. This I know from unfortunate personal experience on my previous engine) A valvespring compressor will aid you in disassembly, and compressed air to pressurize the cylinder will hold the valve(s) open and keep them from falling down into the cylinder. Thus you CAN do the stemseals w/o pulling the heads, but if it were me I'd pull 'em (the heads) and disassemble all (valve assemblies) for a close inspection and good cleaning-then you'd know for certain where things stand. Too early in the bottom end's life to have cause for concern yet, as not enough time on the engine for those rings to have begun seating yet, and until they do you likely WILL have SOME amount of blowby/pressurization of the crankcase at mid-higher rpm's. Fix the known issues and give that motor a chance to find it's happy place!-So far your issues are not severe enough to let them ruin your day. Just a little bump in the road to provide a scuffed-knuckle learning experience. Good luck and keep everyone informed of your progress.-Jim
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