oil consumption-valve guides Re: [Shotimes] Power steering and AutoRx

[Ian Fisher]

Lee/Leigh (which do you prefer?)

Next time I see you, I'll show you my valve guides. I
think the heads had at least 120K on them. They were
some of the nicest SHO heads I have seen though. Now
they are fully rebuilt and will be mated to the 3.2
(your old block) shortly.

Ian
--- Leigh Smith <leighsm@comcast.net> wrote:

> It's all a question of which item wears out first.
> Seal or guide. That
> varies greatly depending on useage, etc. Valve
> guides do wear out on
> high-mileage motors. You can't tell by looking at
> them. The valve stem must
> be checked for "rocking" at about 1/4 in valve lift
> (mid stroke).  Virtually
> any clearance is too much, since the typical spec is
> very tight, llike .001
> in or less. I have seen valves that rocked 1/4
> inch!!! (Non-SHO) Both the
> guide and the valve stem wear, but usually the guide
> is worse. Since this
> requires virtually complete engine & cylinder head
> dissasembly, they are not
> typically checked except at rebuild time. And many
> machine shops won't even
> check them, they'll just automatically go ahead and
> put in new ones (more
> $$$). I have seen 60k mile engines with guides that
> were shot and 185k
> engines that spec'd as-new. Too many variables to
> generalize.
> Once the guides are shot, no valve seal will last
> long. They help for a
> while, then "puff" again. I've heard guys say "that
> engine needs valve seals
> every 6 months...." NO ... it really needs new valve
> guides.
> However, It is possible for a valve seal to dry out
> and crack or leak. Why?
> Heat most likely. If the guides are still tight, new
> seals alone would be
> all that is required.
> Personally I have not dissasembled and checked out a
> set of high mileage SHO
> heads. Has anyone else? What were the guides like? I
> could get access to my
> old ones and have them checked & measured , if
> anyone is interested. Since
> they are presently in the high school auto shop as
> demo items, it shouldn't
> be too hard.
> The easy "fix" is to put on new seals first, if you
> get puffing. Leave the
> heads on the motor, and save some bucks. However on
> a SHO, that job would be
> a major PITA, a lot of labor $ unless you DIY. If
> they don't last long, then
> pull the heads, and have a good machine shop do 'em
> right.
> BTW the guide clearance has much more to do with oil
> consumption than valve
> seals, so much so that some engines do not even have
> a valve seal on the
> exhaust valve.
> Lee
> 
> 
> 
> 
> ----- Original Message ----- 
> From: "Ian Fisher" <dataflash@yahoo.com>
> To: "Donald Mallinson" <dmall@mwonline.net>;
> <shotimes@autox.team.net>
> Sent: Wednesday, April 13, 2005 3:48 PM
> Subject: oil consumption-valve guides Re: [Shotimes]
> Power steering and
> AutoRx
> 
> 
> > Actually, this brings up a question that I wanted
> to
> > ask. I've heard for awhile that the valve guides
> wear
> > over time which causes oil loss. After having my
> heads
> > rebuilt and bronze guides installed, I'm wondering
> if
> > its not the guide seals that are the problem. My
> > guides looked fine. If there ever is a next time
> I'll
> > probably just replace the seals and leave the
> guides
> > alone.
> >
> > Ian
> >
> > --- Donald Mallinson <dmall@mwonline.net> wrote:
> > > And if the oil use was due to bad valve guides,
> the
> > > typical problem with
> > > extreme oil use in the SHO V6, then no oil or
> > > additive is going to help.
> > >
> > > Don Mallinson
> > >
> > > Ron Porter wrote:
> > >
> > > >My '94 had leaky valve seals. On the original
> Mobil
> > > 1 that the POs used, it
> > > >went 800 miles to a quart. Castrol got that up
> to
> > > 1,600 miles/quart. About
> > > >every 3-4th cold start, I would get a puff of
> > > smoke.
> > > >
> > > >After the long drive to CA & back on fresh
> Castrol
> > > MaxLife, the long hours
> > > >of running hot really seemed to help. The puff
> on
> > > startup went away, and I
> > > >only went through 3 quarts for the whole 5,500
> > > miles or so. Which I thought
> > > >was great considering the high temps, track
> time,
> > > etc.
> > > >
> > > >The MaxLife oils seem to work better for crank
> seal
> > > leaks (like my '95 had),
> > > >but it does OK on valve seals...or well enough
> to
> > > forego the expense of
> > > >changing the seals.
> > > >
> > > >Ron Porter
> > > _______________________________________________
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> > >
> >
> >
> >
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