New-To-Me 2003 GMC Sierra 2500HD 4x4

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May 18, 2023
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Good morning,

I recently bought a 2003 GMC Sierra 2500HD after wanting a pickup truck for about a decade.

IMG_8436.webp


Features:
- 6.0L Vortec
- 4L80e transmission
- 4x4
- Single cab
- 8ft bed
- 244,XXX miles as of now
- Engine sounds perfectly healthy
- Transmission still shifts fine
- Allegedly the original drivetrain


Seller replaced a whole bunch of things prior to sale, including:
- fuel filler neck
- fuel pump and filter
- starter
- spark plugs and wires
- shocks
- air filter
- wipers
- battery
All ACDelco parts where possible, they were adamant on only using OEM/ACDelco parts.

All fresh fluids. It does still have Dexcool but it still looks brand new, no rust or sludge. I may do a full flush with a radiator cleaner and put in new Dexcool for peace of mind.

Tires are basically brand new. For a CT truck, the frame is in impressively good condition. Some spots are crusty, but nothing of major concern.

The emergency brake does not work - the cable looks like it split and came apart, so I've elected to replace the whole assembly. There is also a significant oil leak, not enough to put the engine in danger, but enough to drip onto the ground every time I park. It looks to be either oil pan or rear main, both are extremely common leak points for the 6.0. Though I'm not looking forward to removing the transmission if it is indeed the rear main (or rear cover). At the same time, there is opportunity for a new billet oil barbell and a new oil pickup o-ring.

PRNDL lights do not work, which is one of the reasons I suspect silver migration on the gauge cluster board. I haven't gotten a chance to properly investigate yet. I do need to get a multimeter, so if you lot have suggestions for a reasonably priced one I'm all ears.

Rides like a dream! The ride is smooth, it drives straight and the seats are super comfy. Nothing feels loose or erratic. It's quickly become my favorite vehicle to drive. It was jarring at first having never driven a pickup, you are very high up and very long. You also cannot feel the speed, 60mph feels like 30mph. I did verify the speedometer and all the gauges are accurate.

Asking price was $5900, I negotiated it down to $5000. It was the owner's son's truck, he wanted a smaller truck that was easier to maneuver, and the owner was getting back surgery and wanted something he could get in and out of easier. They were good sports and knew their way around vehicles, they were an absolute joy to work with. All the paperwork and everything else was there and lined up.

The bed is the most interesting part of the truck. Apparently, it was first owned by a landscaping company and never originally had a bed. This white one was the only one in reasonable condition that the owner could find, so they used that. Amusingly, as per their listing they said the truck needed a paint job because of the mismatched colors, but it ultimately became a selling point because I love the contrast.

I know next to nothing about towing or the equipment involved, so I haven't a clue what exactly is going on with the hitch receiver. I like the gritty industrial look of it, but I will have to be especially careful because the rails will be unforgiving if I back into something.

truck_time.webp


Admittedly I should've done much more research on this vehicle platform prior to purchase, but I was familiar with the Vortec name and was confident based on the overall condition of it.

Soon to become my daily, replacing a 2010 Honda Odyssey with a blown head gasket and a multitude of other ailments which make it very uncomfortable and unpleasant to drive. This truck is my pride and joy, and I've vowed to literally rebuild it from the ground up if I have to. Irrational as that may seem, given it's a stinky old tradie truck. But it's paid off, and it's mine.

I would provide more photos, but the truck sits back home at an undisclosed location. University calls my name, and my wallet...
 
Sounds like your very pleased with this old truck and that you did get one that was well looked after.
I hope it remains reliable and free of any bad surprises as you use it.
 
These are good years for sure.

That bed looks 6” too short, and possibly like it has an extra spacer in it atop the frame rails. Not that you likely want to put the money there, but a flatbed with headache bar might “work” better. Pretty sure if you put a bumper on it as is - wouldn’t match up right.

The gas mileage might not be too much worse than an ailing odyssey. Staying stock suspension and tires helps.

Driveline fluids? Diffs? Test the 4wd - the actuators in the front diffs are prone to fail, and easy and cheap to fix.
 
Check for pump rub in t-case. If NP261HD or 263HD first make sure there's fluid in there at all. Then fill with 5W20 before it cooks off its ATF.

You can drive without the cluster, so you've got time to pull that and do whatever. I usually prefer to send it out to "the pros" but if you're comfortable with soldering and board work, more power to you!

Nice find, enjoy
 
Good call on the pump rub. The use of 5W20 is interesting, how does it compare to ATF in this application?

I'm skeptical about "the pros," as last time I used a rebuilder for a PCM it looked like they opened it up by beating it with a hammer and then poorly sealed it afterwards.
 
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Good call on the pump rub. The use of 5W20 is interesting, how does it compare to ATF in this application?

I'm skeptical about "the pros," as last time I used a rebuilder for a PCM it looked like they opened it up by beating it with a hammer and then poorly sealed it afterwards.
go to a 5w-30 in the transfer case. it won’t evaporate out like the ATF. i have been running 5w-30 in my transfer case for a long time.
 
Nobody's ever provided an explanation for why the 261/3 cooks ATF, but it does.

Many go one step further by deliberately overfilling from the.....??? VSS? (I FORGET = CRS!!) hole with 5W20 or 5W30.

I never did that (overfill) on our old 261.

There were actually ATSG or ATRA articles on this problem way back. Basically they ended with "run motor oil" and "further study is required." ;)
 
Plan to get familiar with automotive electrical fundementals. Cruise the appropriate forums to gain knowledge of the platform.

Plan on 10 to 15 mpg.

-The instrument clusters fail often on these. Make sure to send it to a good refurbisher like jeffescortlx on youtube if yours fails. Often the circuit traces can burn and this can be a challenging repair. https://www.youtube.com/@jeffescortlx
-Many modules to go bad on these, I may get hate but anything made by "delphi" is suspect. They fail more than motorola, bosch, visteon, mitsubishi, toshiba, and the old school delco.
-These are one of the best riding trucks around and I like the 6.0L and its powertrain, however just like the dodge and fords of that era, these rust very very bad. Especially the frames and rockers.
-I always looked away from these at auction as all of them had some type of electrical problem.
-Never buy aftermarket AC Delco injectors. Only the dealer or known oem used.
-I forgot what module sticks thru the firewall, but one of them will get road wash sprayed on it, and when it finally rots out, it will create a ton of electrical issues that make you go crazy.
 
All good things to know. I was under the impression that Delphi was one of the better ones, I guess they're not quite up to snuff for electricals?

I'm learning the hard way about the rust, the frame and rockers still look decent but I just recently blew a brake line due to them rusting out (will post about that soon). Replaced all of them, fuel lines are next because they do not look friendly. Cab mounts are also very crusty and rotted.
 
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