Ed's blowing oil

["John Hofstetter" <hofs@domain.elided>]

Ed,
Some comments and suggestions.
You need to find out for sure where your blowby is coming from. Do a
compression check, even a cheap compression gauge will give you the
info you need. 
As I remember, you had both cylinder and head damage.  Get a reading
on the cylinder for which you replaced the piston. If it's 80 lbs or
so, hopefully a lot more, but not likely, it's probably OK.  If it is
very low, squirt some heavy oil into the cylinder. If the compression
goes up, then the pressure is going past the rings. If the oil makes
little or no change, then you have a bad valve(s). The oil could be
coming past the guide as they could have been damaged in the trauma
your engine went through. 

With only slight over-generalization, you can't really put in
oversized rings without putting in an oversized piston, and you can't
do that without having the block bored out. Yes you can do this to
only one cylinder, but most people don't because when they have
everything torn down, it just seems to make sense to rebuild the
entire block. Some people will probably express a concern about only
doing one cylinder and causing an imbalance, but I have had a lot of
experience with the motor you have and I don't think you'd have any
problem caused by the replacement piston being slightly heavier than
the other five. 

I visualize that oil could get up through a guide and into the intake
system, but the airflow is in the opposite direction and it doesn't
seem very likely. Going through a guide into the exhaust system is
common. 

You had some cylinder wall damage that, as I remember, didn't clean up
completely with the honing that you guys did, and that could also be
the source of blowby. 

In my opinion, you won't do any further damage to the engine by
driving it. 
John H.
----------
< From: owner-ihc-digest@domain.elided (ihc-digest)
< To: ihc-digest@domain.elided
< Subject: ihc-digest V6 #870
< Date: Mon, May 31, 1999, 8:50 AM
< 

< Date: Sun, 30 May 1999 11:23:04 -0400
< From: edkraus <edkraus@domain.elided>
< Subject: Donut is leaking blood... :(
< 
< Well, you all should remember Donut's saga in NJ with Dan Nees, but
I
< was able to get it home with a lot of Dan's help.  Unfortunately I
think
< We should have used oversized rings on the piston, I think I'm
blowing
< oil past the rings.  I haven't pulled the plug to see if its wet.
I'll
< do that today I didn't really want to know. is there another way to
< tell?
< 
< SYMPTOMS:  I'm getting alot of oil out of the driver side of the
engine
< "tech note: this is an AMC 258 I-6"  It seems to becoming out of the
< manifolds which should be impossible unless it is blowing by the
piston
< ??right??  the exhaust and intake bolt to each other so its hard to
tell
< from which, my luck probably both!
< 
< Question 1)   is there anyway oil can come out of the base of the
< Carb???
< 
< Question 2) can I oversize only one set of piston rings? or will
this
< cause me more problems? the engine only has 10-20 thousand on it
since
< last rebuild, but should it be rebuilt and drilled out to the next
< piston size?
< 
< Question 3) can I damage the engine driving it like it is?
< 
< Thanks in advance,
< Ed Kraus
< Donut 1974 AMC I-6, 4" lift, roll