>When I go onto
>interstate on-ramp, billowing clouds of oil smoke stream out the back,
>and I can smell oil burning.
Maybe you have soooo much blowby it's spewing out through the carb.
>This happens a couple more times on the way down... each time the smoke
>is billowing I also hear a clatter or pinging from up front.
That happened to me once way back in summer of 85 when I first got my B.
Pulling away from a toll booth on a very hot day produced excessive pinging,
like a chorus of twenty kids enthusiastically shaking cans of spray paint.
Checked the rear-view mirror and I couldn't see anything behind for all the
smoke. Very scary, but like I said, it only happened that once.
>Summary:
>1) blow-by increased dramatically in a few days
>2) Compression in #1 cylinder has dropped quite a bit.
Not just dropped, but vanished altogether. Are you sure the piston is still
in there? :)
>3) #1 and #2 have been running lean, perhaps because of blow-by. Clattering
>while smoking could have been pinging due to excessively lean mixture?
Wow! I love these puzzles, but I'm sure glad they're not my problems.
I'd say either your rings are shot, you've destroyed something in the valve
train (valve/seat/guide/etc.), or maybe even burned a hole in the piston
crown. What caused this and what relationship it has to the lean-burn
condition in #1 and #2 might be subject to debate. Too bad both appeared
more or less simultaneously.
a) Increased blowby is causing lean mixture on #1 and #2.
Maybe a ruined intake valve on #1. #2's intake stroke coincides with #1's
exhaust stroke, so gases could be pulled straight from #1 through the
manifold to #2. This would kill some of the vacuum at the carb, cause an
apparent lean mixture, and give all the symptoms of a squirrelly front carb.
b) Lean mixture caused increase in blowby.
A lean mixture would cause excessive combustion temperatures (evidenced by
the pinging). Either the high combustion temperatures or the pinging itself
(knocks and pings are really shock waves--great potential for destruction).
Either way, you're going to have to pull the engine apart and repair
whatever's failed. You should also give the front carb (if not both) a good
inspection and possibly a rebuild.
--
Jay Tilton
jtilton@vt.edu
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