Re: doing valve seals... questions

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

"James F. Creason" <jcre@domain.elided> scribbled in the sand:

>I can't find any specific torque numbers for
>the rocker arm bolts and the valve cover bolts.
>Are there such numbers, or are they just supposed 
>to be 'tight'?

James,

In absence of "specific" torque values given for certain fasteners (like head
bolts), there should be a chart toward the end of the engine section (in the
IH shop manual) that gives "general" torque values.  For example, the IH shop
manual for the 1976/77 Scout II lists a torque of 14 to 16 Ft. Lbs. for a
5/16-18 and 5/16-24 fastener *unless* it's for the oil pump mounting, which
would be 25 to 30 Ft. Lbs.  You just need to figure out what size fastener you
have and if the specific fastener is not named, use the general torque given
instead.  If your shop manual (non-IH?) still doesn't help, e-mail me back
with the size fastener and I'll tell you what my book says.

You definitely don't want to get too carried away on the valve cover bolts.
While the IH valve covers are pretty tough, overtightening the bolts will bend
the sheet metal cover flange and deform the valve cover gasket.  Oil leaks
will be the result. 

>Also the manual makes reference to a "non-
>hardening sealing compound" for the rocker
>arm bolts.  I've read this passage a couple of times
>and don't really understand it, being a none
>too accomplished (but learning) auto 
>mechanic.  Any ideas?

There are two very common non-silicone based gasket sealing compounds that
have been in use for many years.  They are manufactured by many companies but
I happen to have a tube of each made by Felpro.  They usually come in a small
squeezable toothpaste style tube and the compound will have a brown, gray or
black appearance.  These compounds are typically used as a "dressing" for
gaskets to help them seal small mating surface imperfections better.  For
example, if you use a paper or vegetable fiber based thermostat housing gasket
and your housing has small nicks or scratches in the mating surface, without a
sealer, changes are it will begin to seep coolant sooner or later.  A thin
coat of the sealing compound is applied to the surface of each side of the
gasket (or the mating surface of the part).

As you've probably guessed by now, the non-hardening compound stays relatively
soft and pliable (or is supposed to).  The hardening style sets up in time and
gets rock hard.  When it comes time to take something apart, the non-hardening
type is easy to scrape off and clean up with a solvent.  The hard style is a
total PITA and almost has to be sanded or wire brushed off... so most smart
mechanics avoid using it unless it's really needed.  The hard style is
primarily used for applications where the parts being sealed are under extreme
heat and pressure.  In bygone days, it was used to dress head gaskets, etc.
Most modern high pressure gaskets do not require such sealers.  There are many
newer silicone based sealing compounds available that performance wise are
superior to the old type compounds.  But nothing beats the old non-hardening,
easy to clean-up sealing compound for inexpensive all around use.

So all you're going to need is the non-hardening type.  I suspect what the
shop manual is telling you to do is apply a thin coat of this compound to the
bolt threads to seal them and / or prevent them from vibrating loose.

Hope that helps,

John
------------------------------------------------------------------------
jlandry@domain.elided             |
Conservative Libertarian        |  Scout(R) the America others pass by
Life Member of the NRA          | in the Scout Traveler escape-machine.
WA Arms Collectors              |
Commercial Helicopter - Inst.   | 1976 Scout Traveler, V345A, 727, 3.54
http://www.halcyon.com/jlandry/ |