Sounds like you have a nice one! I can't tell by the serial number, but I
would bet the motor is a 6-71 Detroit. They are also known as "screamin'
demons" (all older Detroit Diesels v6-71, 8-71, 12-71, v6-53, etc.) and
other names due to the very distinctive sound that they make. The older
Detroits are great motors, and will run nearly forever if you keep oil in
them. The 72K on the truck is barely "break-in" mileage if the motor has
been cared for. They are all two-strokes and this is what creates the
distinctive sound. The blower is used to pressurize the crank case, and
the cylinder walls have slots cut into them. When the piston comes down
past the slots, pressurized air rushes in to the cylinder from the slots
and forces exhaust gasses out the exhaust valves at the top of the
cylinder. The piston comes up, pressurizes the air even more, fuel is
injected directly into the combustion chamber, the fuel/air mixture
detonates and forces the cylinder back down and the process starts all over
again.
Kevin Lake
56 GMC Suburban/napco
----------
> From: Keith <kvdurand@mail.esc4.com>
> To: oletrucks@autox.team.net
> Subject: [oletrucks] What did I see?
> Date: Sunday, June 20, 1999 2:52 PM
>
> In my quest for a clean, running, and HUGE truck, I've run across a GMC
860.
> Maybe someone here can tell me what this is. I don't know the year. Last
> registered in '71 by the railroad commission. The serial number is
> D86255252J. If anybody has drivetrain details, let me know. It had a 6
cyl
> diesel. Engine casting number is 5115791. I was told it was a Detroit
> Diesel. Had a two speed rear axle and air brakes. What transmission would
it
> have? It had a max GVWR of 33000 lbs and a max combination weight of
65000
> lbs!!! The only disappointment was a door that didn't fit right. It's
been
> garaged for over 20 years and had only 72,000 miles.
>
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
|