This is a 2012 GMC Sierra heavy-duty 3/4 ton pickup truck the 2500 HD this has the
the Allison 1000 transmission along with the 6.6 liter Duramax engine while I've
got it up on the hoist I wanted to look at a few things on this brand-new truck
the very large disc brakes on the rear but the huge American axle this is an
11.5-inch ring gear on this axle and it's a monster rear differential here
great big vibration damper there
drive shaft transfer case and so on but while we're here I want to look at the exhaust system
this diesel this Duramax diesel conforms to the 2010 tier 4 emission standards and
we've got an exhaust cooler at the tip of the exhaust system here I don't know the diameter
of that pipe that looks like four and a half maybe even five-inch exhaust system here but
this has a venturi effect it'll pull air in from the sides as the hot air or has the hot
exhaust that goes out at a pull area in with it and then if we follow that pipe
backward then we come into a new system in the exhaust system here we have the diesel
particulate filter here on the back and of this gigantic piece in the exhaust system we've got
pressure sensors and temperature sensors but on the front part of this is the new part
we have the what's called a selective reduction catalyst or let's see selective thumbs are
selected catalyst reduction SCR where there's a special fuel injector except it's not fuel
there's a special injector right up here that injects what they what GM calls diesel exhaust
fluid into the exhaust system and it goes into this big tank here they're not tank
but catalytic converter looking thing called the SCR the selective catalyst reduction to reduce
oxides of nitrogen emissions NOx emissions and then we also have in this very expensive exhaust
system a regular catalytic converter right here for reducing carbon monoxide and hydrocarbons
and we have temperature and pressure sensors throughout this big exhaust system but this
allows the Duramax engine to be turned way up as far as its power horsepower and torque and
why that's a huge exhaust pipe here's my lose my hand it's a very large very large pipe so we turn
the power way power way up on the exhaust on the Duramax diesel then we clean up the exhaust with
a two-way catalytic converter for hydrocarbons and carbon monoxide we squirt diesel exhaust
fluid which is urea the 32 percent area and in the rest water into the selective catalyst
reduction portion of the exhaust pipe then there's a diesel particulate filter with the NOx a sensor
up there and pressure sensor and temperature sensor temperature sensor up there and then
the exhaust cooler in the back so this exhaust system is been on GM vehicles for the last two
model years 2011 2010 arm so 2011 2012 with the Duramax engine this Duramax has 765 pound-feet
of torque very powerful engine and of course with the Allison 1000 automatic transmission
that's been up rated the Allison calls it on their website for this new more powerful engine
but I wanted to show this exhaust system what a gigantic and expensive I here upwards of $10,000
for exhaust system the complete exhaust system for trucks like this but this exhaust after-treatment
system which is what we call it is really good at cleaning up the exhaust of a very powerful
diesel engine that they've been able to turn out the compression ratio the boost get much higher
power ratings out of the truck out of the engine then we were in the past due to the fact that
we do have this exhaust after-treatment system available actually it's required as part of the
tier 2 emission regulations is to have a certain exhaust emission regulation meant here on the side
of the truck underneath the passenger side door is a diesel exhaust fluid tank it's kind of in
a bad location but it is what holds the roughly five gallons five and a half gallons I think of
diesel exhaust fluid that you pour in underneath the hood of this vehicle and then that's used to
spray in the exhaust system to clean up the NOx emissions alright I've let the vehicle down that
was on the hoist this Duramax 2012 GMC Sierra pickup truck with 6.6 liter Duramax and I want
to show you the engine and the place where you poured the diesel exhaust hood in to that tank
that we saw underneath the passenger side door outside the frame so here's underneath
the hood and then right here in the back by the battery one of the batteries as you can see is
the reservoir cap for diesel exhaust fluid has the international standards organization
standard number for that fluid must meet of course GM prefers you use their diesel exhaust
fluid but as long as it meets that standard I think you're OK to pour it in but according to
GM you're supposed to use only the GM diesel exhaust fluid but as long as it meets that
standard it should be the same thing this engine uses the piezoelectric fuel injectors which allow
for multiple pulses and much finer atomization of the fuel the orange housing here and the orange
wiring down below indicate high voltage like in a hybrid and I forget what the voltage is that
is used for these fuel injectors but it seems like it's a max maximum of around 165 volts somewhere
in that range so this is a 2012 GMC Sierra it's very interesting the emissions decal it meets
the ultra low emission vehicle emission standards which is amazing for a 3/4 ton heavy duty truck