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

Sat Nov 27 23:30:43 EST 2010

On 11/27/2010 20:01, Will Kooiman wrote:
> 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.
Hahaha... I was a bit past that point and it -was- making noise. :)
> If you leak debris past the oil filter bypass, it wouldn't pick on one
> bearing.  You would see debris on all bearings.
I've only taken off number 2.  I expect I'll find similar ugliness on 
the other 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.
Wow, I didn't even see that until I looked at the photo again.  I went 
back to the garage and took my dental pick to it.  Turns out it was just 
a hole in the carbon debris.  I managed to scrape it all away and 
couldn't find any pinhole, though a more thorough inspection will tell 
me more.
> PB270029 - is that rust?  Maybe some water is making it into the cylinder.
> Hmmm...
Yes, that's surface rust.  The engine has been sitting on a stand for 
nearly 10 years.  Prior to that it sat in the car either in or out of a 
garage for a year or two.  I suspect most of the valves and seats will 
appear similarly.
> 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?
Not necessarily.  The first conclusion one might jump to is just such a 
scenario.  The heads were reconditioned at a local very reputable shop.  
I also would have inspected the mating surface prior to installing.  A 
feature like this would have stuck out like a sore thumb.  However, it 
does baffle me how it really would have got there.
> 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?
The intake valve seal is a positive type rubber seal with metal clips.  
It's not the umbrella type.
> Can you pull all of the intake valves?  How does #2 compare to #1, #3, and
> #4?
I'll remove some more valves later as it would make a good comparison.
> 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.
I'm interested myself, to know if the other pistons appear the same.  
I'll get after them later.
> Just thinking out loud...
It's all good. :)
Asa Jay
> -----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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