Re: Engin Id and Oil seals

[jlandry@domain.elided (John A. Landry)]

When he stopped taking his medication, strange voices in John Fleck
<jlfleck@domain.elided>'s head said:

>To John Landry and others
>
>WHY would anyone want to second guess the IH enginerrs who designed the
>valve seals to properly let a few drips of oil in the cyclinder after
>sitting so as to aid in starting up and reduce dry cyclinder startup
>wear??? I just dont understand thats one reason why
>IH motors last so long.

Well Johnny... since you asked... I'll tell you.  This is of course just
*my* opinion, so you can take it or leave it as you see fit.

For starters, the original design of the valve stem seal is *not* why IH
engines last so long.  They last so long because they are essentially way
over built in just about all design areas for an application such as a
small truck.  The cast iron is superior and the strength of most parts is
superior to anything else out there.  Why do you think they weigh so darn
much?

Getting back to the valve stem seals.  The information below is what I just
told Steve Stegmann (more or less) when we were discussing different types
of valve stem seals...

-------

Well for starters (as you know already) the stock setup was a small o-ring
that *barely* seals the ID of the valve spring retainer.  The concept with
the o-ring seal IH used was (is) to keep oil from running straight down the
valve stem (from the valve spring keeper) and into the valve guide.  After
a period of time the rubber of this seal hardens, cracks and many times
disintegrates so the it's effectiveness is greatly diminished or
eliminated.  After engine shutdown, the hot thin oil which has pooled
around the stem in the valve spring retainer leaks down the stem into the
guide.  This is what causes the puff of oil at startup so common with IH
engines (from the intake guides).

Next is all rubber umbrella style seals and their variants.  They of course
fit over the stem like an umbrella and act to deflect the oil from either
being sprayed or dripping into the valve guide.  Some are designed to grip
the valve guide and not move and others ride the stem up and down.  With
this design, it's pretty much agreed that they very effectively prevent oil
from getting into the valve guide.  Whether this is a problem with the
stock cast iron valve guides used in IH engines is a matter of debate.
Some say it's not a problem, others say it is.  Personally I'm not taking
any chances and I feel a tiny bit of oil can't hurt and is probably a good
thing.  The other thing I dislike about the old fashioned rubber umbrella
seals is that sooner or later they are going to harden, develop cracks
where they meet the stem and then you'll get oil leakage.  But that would
take many years assuming they are of high quality.

In the case of Perfect-Circle type seals (I say "type" because there are
several manufacturers who make similar products), they do in fact look
similar to the all rubber umbrella style seals but have a small teflon ring
or "wiper" in the center.  The PC seal has a metal wire spring around the
outside and is designed to slip over the mouth of the guide and stay their
tightly.  The valve stem then moves up and down being wiped by the teflon
ring while the seal stays put on the mouth of the guide.  It looks like a
little cap over the mouth of the guide.  The teflon ring is designed to
allow a small metered amount of oil to lubricate the valve stem inside the
guide.  I was told this when I spoke with an engineer at Dana.  So
obviously Dana thinks a little oil is a good idea too.

In the case of the IH 392, Perfect-Circle does not make a seal to fit the
larger non-standard sized exhaust valve.  So I'm only able to use them on
the intakes, which is of course where 90% of any problem with oil leakage
would be.  This is not a problem with the 304/345 as both the intake and
exhaust valve stems are the same diameter.  With the exhaust on the 392,
I'll be using the traditional stock o-ring type seal.  BTW, the instruction
sheet from the PC seals specifically tells you *not* to use any other type
of sealing system *with* their seal (on the same stem).  This of course
means the stock o-rings are left off stems that will use the PC seal.  I
gather that this is so oil will be present on the stem above the seal so a
metered amount can be allowed past to lubricate the valve stem.

------

So Fleck, like you and many others (John Stricker comes to mind), I think
it's a good idea to get some *small* amount of oil into the valve guides to
lubricate the valve stems.  I would think this would reduce wear over the
life of the engine and help prevent galling under high heat / load
conditions.  But there's nothing inherently wrong with the original style
o-ring seal IH used, except that there are *better* seals available now...
namely the rubber / teflon Perfect-Circle seal and variants from other
manufacturers.  The rubber o-ring seal will sooner or later become hard and
will quit doing its job.  This is evident by the smoke-at-startup you see
in just about every high milage IH engine.  Those rubber o-rings don't have
a very tight fit between the valve spring retainer and valve stem.  And
then they do nothing to reduce oil consumption from oil being sprayed or
splashed onto (and then sucked into) the valve stem during operation.  The
more the clearance increases between the stem and guide, the worse the oil
consumption would be, so just as the old o-ring seal is failing, a high
milage engine needs a good valve guide seal the most.

So that's why I spent the extra $50.00 or so in acquiring the Perfect
Circle seals and cutting tool from NAPA to do my 392 I'm rebuilding.  The
cutting tool will last a lifetime... let me know if you'd ever like to
borrow it.  The seals come 16 to a box, so because I could only do the
intake guides on the 392, I have 8 left over for my next rebuild project.

Best regards,

John L.
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