[DeTomaso] Asa Jay's 1985 built 351C Forensics part II

[Will Kooiman]

If you leak oil into the cylinder, either past the valve seals or past the
rings, it will cause pre-ignition, which will beat the crap out of the
bearings.  If it happens on just one cylinder, you might not even hear it -
esp. as a teenager on puberty-roids.

If you leak debris past the oil filter bypass, it wouldn't pick on one
bearing.  You would see debris on all bearings.

If you leak water into the cylinder, it will be nice and clean.  The water
steam cleans the cylinder.  Been there many times.

PB270024 - this pic looks like there's a pinhole in the head on #2.  I'm
sure you would have commented on the hole, though, so it's probably just an
illusion.

PB270029 - is that rust?  Maybe some water is making it into the cylinder.
Hmmm...

PB270034 - the depression on the gasket caused by the buildup?  There would
only be a depression on the gasket if the buildup was there before the heads
were torqued - unless the heads were warped - or if the heads weren't
torqued properly.  Right?

I agree - the valves look like the valve seals did their job.  If they were
leaking, I would expect a bunch of crap on the valve head.  I don't know
about the intake valves, though.  If the intake valve seal was leaking,
would the fuel keep the valve clean?

Can you pull all of the intake valves?  How does #2 compare to #1, #3, and
#4?

Can you pull the rest of the pistons?  I wouldn't expect crap from the
combustion chamber to make it all the way to the oil control rings.  Maybe
it would. I don't know.  At any rate, if the oil control rings are full of
crap, then maybe they were the cause.

Just thinking out loud...

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of Asa Jay Laughton
Sent: Saturday, November 27, 2010 8:52 PM
To: detomaso at realbig.com
Subject: [DeTomaso] Asa Jay's 1985 built 351C Forensics part II

Today in Asa Jay's garage, we take a closer look a the weirdness we 
found in number 2 cylinder yesterday.  My focus was -only- on cylinder 
number 2.  I did not disassemble any more of the engine that just this 
cylinder.  The rest will come later.  For today, I inspected the head 
surface, intake gasket, head gasket, removed the two valves from the 
cylinder, removed the piston and inspected both it and its bore.

The photos are here:
http://www.351c.info/gallery2/v/asajay/1985buildforensic/

You'll probably want to pick up the story at this point:
http://www.351c.info/gallery2/v/asajay/1985buildforensic/PB270022.JPG.html

The intake gasket shows that it was totally sealed against both the 
intake and the head.  The seal is a type that also blocks off the 
exhaust gas recirculation port.

As Doug Braun pointed out, he thought he saw some deterioration between 
cylinder 1 and 2.  I closely  inspected this area and he was correct.  
On the head, there is a thin buildup of carbon in a small triangular 
area between the cylinder sealing rings.  On the gasket, there is a 
corresponding depression.  It very well may be there was a cylinder to 
cylinder leak between 1 and 2.  But if that were they case, why would 
only one cylinder show the nasty carbon buildup?  Could it be due to the 
firing order?

Next I removed the intake and exhaust valve on cylinder number 2.  They 
both look fine.  No indication of leaking past the valve guides, which 
by the way have a positive seal on them (forgot to take a photo).  A 
nominal amount of carbon buildup on the intake and the exhaust appears 
good as well.  The ports in the head are also clean.

The piston appears to be in one piece, no cracks I can see.  The 
compression rings also appear to be in good shape, they both still have 
spring left in them though they are very shiny on the edge.  They do not 
appear to be broken.  The lands on the piston appear to be okay though 
I've not removed the rings yet.  The oil seal has a lot of carbon on it 
and is nearly stuck in place.  It does not appear to be broken and does 
move some, but you can definitely tell it has some buildup.

The cylinder wall looks good.  No cross-hatching visible anymore.  Very 
shiny.  I can't perceive any cracks though it may take a dye or 
magnaflux test to know for certain.  This block was originally bored 
.030" over so I most likely won't use it again for anything.  I may try 
to find a machine shop to hack it into sections for me for illustrating 
other internal stuff.  :)

One thing to note is the condition of the rod bearings.  I've only 
removed one mind you, but it looks terrible.  It appears to have taken 
in some very small debris, the kind that can get through the pump and 
bypass the filter when cold.

Alrightly, take a gander at the photos and see what you think.

Asa Jay


Asa Jay Laughton, MSgt, USAFR, Retired
&  Shelley Marie
Spokane, WA
******************************
http://www.racingagainstautism.com
http://www.teampanteraracing.com


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