Home » Public Forums » GMCnet » [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed.
| Re: [GMCnet] Tid Bits: Oil consumption. It's all in how/where it's consumed. [message #336532 is a reply to message #336531] |
Thu, 30 August 2018 09:32   |
James Hupy
Messages: 6806
Registered: May 2010
Karma:
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Senior Member |
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You guys need to listen to the guy that represents AM General ( they make
the Hummer, both civilian and military versions) When they bought the
production rights to the Hummer from GM, they bought the engine
manufacturing production line, tooling, everything but the actual foundry
where iron castings were produced. They did acquire a bunch of bare engine
blocks, and when they set up the production line, they found out why GM got
rid of the Hummer. High graphite content in the cast iron led to long
tooling life, but crappy strength and durability in the engines. Threaded
holes pulled out in service, lost their clamping ability, led to Internal
coolant and combustion leak failures, short engine life, etc.
When AM General switched to high nickel content in their new block
castings, the used tooling that GM sold them failed quickly. Leaving AM
General in a pickle. A few band aid fixes were tried, and failed.
AM General bit the bullet, and did a total redesign of the 6.5 Diesel.
That included castings, tooling, production machines, durability testing,
the whole deal.
The 6.5 that they build today is the same displacement as the GM built
one, and that is about all they have in common.
AM General spent BILLIONS fixing the shortcomings. So, the product
development processes that GM used on our Olds engines in the 60's and
early 70's, disappeared, and brought us products like Volera, Saturn,
Fiero, Astro, to name a few. That led to the demise of Saturn, Pontiac,
Oldsmobile, and a huge government bailout of what was left. Better? Not in
my world.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Thu, Aug 30, 2018, 6:59 AM Richard Denney wrote:
> On my old engine, I was getting about 15 psi at idle, and 30 or so at
> speed. The engine had an uncertain history (valve covers were painted
> black) and 90k+ miles, and I switched to Mobil1 High Mileage 15W-50.
> Pressure was 20 at idle and 35-40 at speed after that. Which is plenty. But
> I didn’t make that change to get higher pressure, I did it to get a
> stronger oil film in looser bearings.
>
> Dick P once said that NASCAR racers can run all day at 30 psi and 8000
> RPMs. Pressure is not what we need—an ever-present film is what we need.
> The problem with worn tolerances is not so much that they relieve pressure,
> but that they leak a lot of oil. A high-volume pump prevents those leaks
> from causing starvation somewhere else.
>
> Do we need it? Certainly not for a tight engine. But I don’t worship at the
> altar of GM engineering, either. They did as much cost engineering,
> fuel-consumption engineering, and emissions engineering as they did
> durability engineering. Their engines were tight not because they made the
> parts fit (as we expect to do during a rebuild), but that they selected
> parts with the right dimensions for the assembly task at hand. As I
> understand it, parts were sorted across their manufacturing tolerance range
> and the selected on the line as needed. They were auto workers, not
> artists.
>
> Rick “who uses a mechanical oil pressure gauge” Denney
>
> On Thu, Aug 30, 2018 at 12:48 AM John Phillips
> wrote:
>
>> What does changing the oil weight do the oil pressure? I feel my oil
>> pressure is low. Would like to have a real gauge. Coach has 117k miles.
> OP
>> said it was reabuilt at 100k.
>>
>> --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
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