Larry brings up a point worth remembering: We've had engine programs of
various types come and go.
Some were in search of excellence (8.1), and some were in search of cost
control (Jasper). But they go because they are built on an unsustainable
business model. Either they require artistry in installation, or they
pushed too far the compromises needed for cost control.
What we have ended up with is specialty engine builders who are willing to
learn what needs to be understood to make an Olds engine reliable in this
application. But there is risk there, and the shops struggle with that risk
(and struggle to justify pricing that compensates them for that risk).
The problem is that when someone blows an engine, they have it towed to one
of the GMC shops, who then have to source a replacement engine with a blown
core. The core, because it blew, may have scored cylinders, or a cracked
block, or damaged main-bearing journals, or be otherwise too damaged to
salvage, and another 455 goes into scrap. And without a stock of usable
cores, each customer with a blown engine has to face whatever it takes to
make their core work, or wait until another core can be sourced. The cranks
I'm less worried about--they are (at least currently) replaceable with new.
Good rods and pistons are still available, as are all the other bits that
go into the engine. We have also learned how to manage the problem of flat
tappets by using specialty break-in oils that make sure they are properly
broken in.
The issues Mike mentioned with the unknowns are not really unknowns, and
the 30 hours of labor the shops usually charge includes most of them
already. The issue is not having a core that can be rebuilt--the is the big
unknown.
The solution to that is simple, but scary to some: Replace the engine
BEFORE it blows. Larry mentions airplane engines, about which I know little
except what I hear from airplane owners. Airplane engines bring up a
principle about how to know when it is time to overhaul an engine--they use
hours. Most GMC (and other land-vehicle) owners use health indicators: Oil
pressure, temperature, oil appearance, (supposedly) routine compression
checks, and (probably best) oil analysis. Many GMC owners use nothing more
than the dash gauges and i...ndicator lights.
The most important indicator, and the one suggested by airplane
maintenance, is this: The odometer. I recall something I read on Gene's
site many years ago. Here's the link:
http://bdub.net/gmcmotorhome.info/safety.htm
In that list, he mentions a range of things that should be considered for
safe, reliable motorhome ownership. He mentions maintenance of wheel
bearings, ball joints, and not letting tires age out, but then he writes
this (and you can tell how long ago he wrote it):
Quote:
4. (May not be truth, but I believe) if you have 100,000 miles on your
20-year-old coach, you need new:
- engine
- master cylinder
- vacuum booster
- fuel lines
- fuel pump
- water pump and fan clutch
- brake cylinders
- alternator
End quote.
The point is not that these items can't last longer, it's that after 100K
miles, they are on borrowed time.
That's partly why I replaced my engine at 103,000 miles. John Beaver had a
core, and now he has another core that was good enough to drive me down to
Georgia for the swap. Someone else will get that one, and if they do it as
an item of regular maintenance, rather than waiting for the engine to blow
up, their core will stay in the system, too. (Most of the other items on
Gene's list don't last that long--I've replaced most of them long before
reaching 100K miles).
If everyone did that, we'd have fewer problems with rebuilt 455's, in my
view, because we'd be rebuilding better cores in the first place. That
would help manage the risk the shops assume when they replace an engine.
That doesn't mean there is no value in exploring alternatives, but it has
to be done in a way that can be sustained commercially as well as
technically. That means a conversion should be doable by a regular shop,
not by an artist who is not charging a customer by the hour. I think that's
what Mike is aiming at, but the business model issues are more likely to
kill the program than technical roadblocks. For example, there is one
conversion that has been proven reliable and sustainable beyond the one-off
experimental phase, and that's Manny's diesel conversion. But it's
expensive, and it still depends on Manny's willingness and ability to make
it commercially feasible. That conversion costs about $40K, with "about"
being a big word. It's a good model to follow for anyone who is seeking an
alternative power plant using a newly manufactured engine. But it still
depends on the TH-425, and that is probably less sustainable in the long
run than the Olds 455.
Rick "sorry for the length" Denney
On Thu, Jun 8, 2017 at 8:31 AM, Larry Nelson I love this discussion.......whenever it comes up. I am older than my
> motorhome by exactly 30 years and I admire you guys that still have it in
> you to
> get down on the creeper and start wrenching.
>
> From what I can tell my 455 has about 115k on it. Back when was much
> younger, if an engine got tired you pulled the heads, had them "done" and
> hope
> the rings and cylinders will survive the "new" heads. I guess that is not
> done anymore. Sometimes we would pull the pistons, hone out the cylinders,
> and re-ring it and go about our business because we needed the vehicle to
> get to work and feed the family (obviously not referring to a motorhome).
>
> In the aviation world, where I spend most of my $$$, we have top overhauls
> and major overhauls. I am suggesting our old approach with the family
> driver was more of a "top" overhaul, but not really because you could get
> everything but bottom end work redone in a top overhaul, and in fixing the
> family driver as described above, the bottom end and cylinders would still
> be in the dark.
>
> When I started with my first GMC, the Jasper engines and Danny Dunn
> trannies seemed to be very popular. I had a Danny Dunn in my first PB.
>
> Anyway, times change. I just want reliability. Don't need to go 75 mph and
> pull 10,000# up a mountain grade.
>
> Keep talkin, folks....love it!!
>
> Larry
> --
> Larry Nelson Springfield, MO
> Ex GMC'er, then GM Busnut
> now '77 Eleganza ARS WB0JOT
>
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--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com
