2005 GMC Sierra 2500HD - Turd Polishing

I've been hankering for a new-to-me truck for a while now. My '98 K1500 has been a fantastic truck, but the 5500lb tow capacity sucks, and I'd like to get an enclosed trailer. An enclosed trailer would double as weather-proof parking spot for my race car without building a new garage, since I'm planning on moving in the next couple of years. Truck prices are crazy right now, I'm okay with getting a fixer upper, and the older the truck the cheaper the insurance. So  I had my eyes on a gas powered 3/4 ton.

This popped up for sale about 4 hrs outside the city. I resisted for almost a week, then gave him a call.

So here's what I got.

It's a 2005 GMC Sierra 2500HD SLE crew cab, 6.5" bed 4x4 with 303,000kms (188k mi) with a 6.0L gas motor and 4L80 transmission. It's been a farm truck for the past 13 years, so it's had a hard life. I paid the $3000 CAD asking price (about $2350 USD) as the seller delivered it to me, and also had put a new battery in it. Date of purchase was Feb 7th 2022.

Tire are shot, windshield cracked, left side mirror cracked, exhaust leaks at both exhaust manifolds, the airbag light is on, needs an outer tie rod, lower balljoint, rear shocks are bashed up, and some minor oil leaks. I'm going to keep track of the repairs and hopefully upgrades here.

Feb 11th + 12th 2022 - starting on the rust

I cut the outer rockers off. The drivers side is worse than the passenger side. Both sides had a large amount of muck trapped inside. Pile of frozen mud, manure, and hay:

Passenger side in decent shape, only about 20" had deep enough pitting that I want to replace. I covered it all in rust converter after this pic

Drivers side has almost the whole lenth badly pitted plus some holes. About 60"

I had thought the inner rockers would be fine, but just at the bottom they have some holes from the muck. I got some cheap Keystone brand rockers, they're supposed to be for an extended cab but almost cover the whole crew cab length. They're about $50 each. Oh, and I ripped the chrome bump pads off the door too

Also spent way too long scraping dirt, rocks, manure, and hay from the under side of the truck.  It looked/felt bigger than the picture suggests

Feb 14th 2022  - new windshield day! I paid $340 for it. I've done winshields myself before, but felt it was worth it to pay a pro.

Feb 15th 2022

The first Rock Auto shipment arrived. Got the lower balljoint, outer tie rod, transmission filter and pan gasket, MLS exhaust manifold gaskets, exhaust manifold bolts, a brake hose, engine air filter, front axle seals, and an AC belt for $295 CAD shipped/taxed.

Started with the new air filter and washing out the intake box.

Then the exhaust manifolds. It only had one broken stud, on the drivers side rear. The passenger side was just a cheap blown out gasket from when the previous owner had the head re-done.

This was my first time using a welder to extract a stud, took me 4 tries. You can see how I got more heat it in each time.

Interestingly the passenger side manifold is a Dorman unit for some reason. The muddy one is the original for the drivers side.

Not flat

I attacked them with a belt sander and whizz-wheel until they were pretty straight. Whizz wheel did the heavy removal, then sort of used the belt sander to find the high spots. The right side Dorman unit was basically straight already.

Put it back together with Mahle MLS gaskets and some new Dorman hardware. Sounds way better now. I would have liked to do ARP studs or something, but this was like $20 of parts and the ARP would have been $150+

Feb 16th 2022

Replaced the right front lower balljoint with a Mevotech TTX unit. Seems nice quality. The left side has a bit of play as well, but it's under GM specs. Uppers are good.

My inner rockers arrived too, these were pricey at $350 CAD.

Tonight (Feb 22) I just had a little time to cut out the worst bit on the passenger side inner rocker. Keep finding more mud hiding inside various crevices.

I'm thinking of just replacing that bit there rather than the whole rocker. My thought is that the factory ones fit better, have better corrosion resistance, and should it ever rust out again in my ownership it's easier to replace with the factory spot welds than the plug welds I'd do.

What do you think? Critique and tips on the work or chevy truck ownership in general is welcome!

Nice score! My '04 2500HD is a great towing rig. It gets 13 mpg, empty, full or with our fifth wheel. Not economical, but a reliable work horse. 

Great score!  I've always enjoyed an old truck to work on than a new one.  It should serve you well.

My 01 with the 8.1 was one of the best truck trucks I've ever had. I'd piece that rocker together, for the reasons you stated.

Good trucks,  I've got an 03 myself.

You might be unimpressed with the performance of the 6.0/2500 vs your old 5.7/1500 empty.  We have both trucks and the '96 1500 would smoke the 03 2500 in a drag race.  Both have around 240k mi

They are thirsty and have adequate at best power, but super easy to work on and reliable beasts

Edit:

Good choice on the MLS gasket.  After replacing some broken manifold bolts I used the felpro standard gaskets and they leak.  Goes away for a bit after tightening the bolts for a bit then comes back.  Have some MLS ones going in when I swap in a low mile 6.0 in the next couple weeks to replace my current one that is making glitter oil.

I really enjoy my 06 2500HD with the 6.0L gas, seeing you rockers reminds me I need to tackle mine soon.

I'm willing to bet the Dorman manifold was replaced because the head was off, and was probably not flat as well. What better way to pad the invoice than adding new parts and associated labor?  

Looking forward to seeing how it works out for you. 

Glad to hear they're well loved, I'm pretty sure this is what I want, just a little uncertain if this particular example is the best choice.

I suspect from the reading I've done that the poor mileage and less-than-expected power is mainly due to the 4L80, with it's tall gearing and the extra power it sucks vs the 4L60 trucks.

I'm having a debate on tires. The truck has 245/75/16 K02s that need replacing. I have a set of good LT265/75/16 studded General Altimax on my '98 for winter, and some like new LT285/75/16 Falken Wildpeak AT3W for summer. Pretty sure I'm going to keep the studded winters for this truck, but unsure if I want the 285s on this truck. Ideally if I were to use them, I'd need another set of wheels as the stock ones are only 6.5" wide, plus maybe some minor trimming for clearance. Then I could sell my '98 K1500 with some cheaper P-metric 265s. Buying a set of stock size LT245s would probably result in the best fuel economy. Maybe going up one size to 265s would be a decent compromise in mileage and looks? 

Not having much luck looking at the used market, people seem to be able to sell tires with 40% tread at 50% of retail pricing. 80% tread are listed at about what you can find shopping new online.

I know Michelin LTXs are regarded as the best highway truck tire, but boy are they pricey. General Grabber AT/X are a decent deal. BFG K02s are surprisingly affordable. I like my Falken Wildpeaks a lot, but they've gone up a bunch in price too. Duratracs are hugely popular around here, but I've noticed they all seem to cup pretty bad. Also expensive. 

Continental Terrain Contacts are looking like a decent sweet spot, plus Conti supports the Dinner with Racers podcast and Speed Academy Youtube channel I enjoy.

In reply to Run_Away :

I have LTXs on my Ram 2500 and they ride well, wear like iron and are amazingly good in snow.  I have a set of Generals on my wife's new Wrangler and they are decently quiet and are particularly good in the wet.  They were also a lot cheaper than the Michelins.

I've tried buying used truck tires in the past but have had little luck.  However I've bought many near-new set of tires on wheels for very reasonable prices.  Look for takeoffs from a later model and you may accidentally bump into virtually new wheels and tires on the cheap.  Then you can liquidate some of what is on it now to recoup some of the cost.

I run 285's on the stock wheels, great combo and offsets the 4.10 gears a little. You may need to slightly trim the valence but that's it.

4l80 doesn't help, nor does the fact that they are 1000 lb+ heavier than a 1/2ton. From what I've seen the lq4 tune is extremely conservative on timing and generous on the VE table. These trucks were meant to be worked hard, not be fast/efficient 

pic of mine on 285's for reference, I think they look correct on these trucks

285/75/R16 Duratracs. Slight poke and tons of grip. 12K miles on them and no noticeably uneven wear. 

That's a good score. I love gmt800's and have had several. Most recently a 1500HD with the same engine/trans combo. I always found them to be dead reliable and the interior worked well for me. Comfy seats, well placed buttons etc. 

If you have access to HPtuners, simply enabling power enrichment will get you a good power bump without touching anything else. A google search for "LQ4 power enrichment" will yield a ton of results. 
 

Do you know if you have 4.10 or 3.73 gears? The 4.10 ratio does so much better towing, especially in the mountains where I live. Especially if you go with 285/70/17 tires which is what I did. If you check in the glove box you'll find the RPO codes on a sticker tag. I think GT4 is for 3.73. G80 is the LSD. Don't recall what the 4.20 code is.

Pic of my truck on 285 General Grabber ATX's. Yours should sit about 1.5"-2" taller being a 2500HD.

I'm sad to see the gmt400 go, it is pretty much the same truck as mine but I have the red interior.

Really nice gmt800 though, i look forward to following the thread. A buddy did 285 ko2s on his stock wheels and they look great.

I like the LTXs for a street tire I haven't ran into anyone that regretted the purchase once they drove them. Ko2s are a favorite AT, I've heard good things about the grabbers but never ran them, and I do have a little bias against Generals because of some of the junk they used to make, but it seems they really worked on their truck line in the last decade.

I had Duratracs on a previous truck and found them to be unstoppable in snow in the mountains. A price premium over some other AT's but a great tire. Tons of siping and a fairly soft compound. The thread looks like a mix between an all terrain tire and a snow tire. They do make them in E rated load range which is what you'll need. 
 

Most recently I had general grabber ATX. Also severe snow rated. Not quite as good in the snow as the Duratracs but 85% as good and much much cheaper. They wore well with little road noise. No complaints and I would definitely buy them again given the lower price point. 

In reply to WillG80 :

+1 for Duratrac snow capability. We got a fair amount of snow this year and the issue I've had with my commute was falling on my ass once. These tires dug through 3' standing powder before the plows ran, hard pack, everything.

They held up well hauling our small fifth wheel as well. If they wear relatively evenly, I'll be happy to buy another set in a few years 

WillG80 said:

That's a good score. I love gmt800's and have had several. Most recently a 1500HD with the same engine/trans combo. I always found them to be dead reliable and the interior worked well for me. Comfy seats, well placed buttons etc. 

 

If you have access to HPtuners, simply enabling power enrichment will get you a good power bump without touching anything else. A google search for "LQ4 power enrichment" will yield a ton of results. 
 

Do you know if you have 4.10 or 3.73 gears? The 4.10 ratio does so much better towing, especially in the mountains where I live. Especially if you go with 285/70/17 tires which is what I did. If you check in the glove box you'll find the RPO codes on a sticker tag. I think GT4 is for 3.73. G80 is the LSD. Don't recall what the 4.20 code is.

 

 

From my understanding the 2500HD/LQ4 always got 4.10's and the 1500HD/2500LD got 3.73's.  I was hunting high and low for a 2500LD but despite being overkill for my needs couldnt pass up the deal on my HD

I really want to open mine up on HP tuners but know myself well enough that it'll get out of hand.  Really hard for me to not toss an aftermarket cam in the replacement LQ4 I have on the stand too.

As far as tires go, Wildpeaks have been my go to lately.  Favorite tire I've ran were a set of Michelin LTX A/T 2's that I had on my 99 silverado 1/2 ton.  Quiet, lasted forever, great in the rain and dry off road conditions.

Also, check out the Khumo Road Venture AT's.  A buddy ran a set on a 7.3 diesel econoline, twin I beam/diesel is hard on tires and he got amazing life out of them.  According to him they seemed to be a harder compound but worked well on a heavier vehicle.

My truck has the 4.10 gear and G80 according to the RPO codes.

I think Duratracs are out, I don't need their snow capability as I have dedicated winters. Here's my spreadsheet with various models and pricing in the two smaller sizes, if I go that route. They are sorted in ascending order of price, green cells are the cheapest source for that model of tire.

Friday Feb 25th, changed out the LF outer tie rod before work close. Went with Mevotech TTX, the one that came off had a blue boot so I'm assuming it's a Mevotech Supreme as that's what part stores carry around here as their main line. Visibly beefier

Sat Feb 26th hit the junkyard. Most trucks were burried in 3ft of snow and been picked over pretty well, but there were two fresh arrivals.

3500 2wd with a 6.0L

And a '05 Suburban

Suburban was interesting because it had a 5.3, electric rad fans, hydroboost, and a 160A alt.

I got the alternator, belt, fans, heater controls, left mirror glass, antenna, and front crash sensor from the 3500 for $105 CAD after tax

I needed the front air controls because a few hours after purchasing I had pulled apart my original controls and broke the passenger side temp potentiometer being hamfisted trying to get to the burnt out bubs. I'll be more careful with this one...

My blower didn't on speed 5, turns out the 40a fusible link was blown. Fan also has a nasty vibration, pulled it out and found it caked with dust, gave it a good cleaning and now it's quiet and smooth.

The crash zone sensor turned out to be the wrong P/N for my truck. I'm a little sketched out using a used sensor, but a new one is $150 and the junkyard didn't even charge me for this one. Double checked the bags weren't blown in the truck they came from...

Procrastinating doing bodywork, started chasing down why the left rear window doesn't work. Have 0.8V at the orange B+ wire at the switch, same at the inside of the B pillar plug

Check out the dirt and straw under the sills. I started following the orange wire, but instead of continuing to the fuse box it snakes under the front seats, so I'll chase that down at a later date when I pull all the seats and carpet to clean.

Patched up the passenger inner rocker

Then cut and did the fitup for the outer rocker. Ran out of self etching primer, so that's where I stopped. I want to get everything inside the rockers well coated before I close it all up.

Debating using a brush and oil based paint or spray paint (probably the winner of the Project Farm video, I think it was rustoleum PRO?). I do have some POR15 I need to use up, but I find that stuff doesn't stick well to smooth or previously painted surfaces. Suggestions?

I'm going to go back and fill the rockers with fluid film, cavity wax, or cosmoline after too.

I think I'm going to head back to the junkyard today, grab the wiring and relay box for the electric fans and maybe the front fenders from the 3500. They were exceptionally clean. I don't have a radio either, the Suburban one was nice but it had the Bose system and I don't know if that needs an external amp...the Nissans I work on with Bose systems usually do. It'd also be nice to have steering wheel controls, but not sure how easy that is to retrofit. I should focus on getting the basics fixed up and working before I pimp it out...

Didn't go back to the junkyard, realized Chevy fenders are not the same as GMC fenders.

Progress in the past week:

I snagged some LT245/75/16 Duratracs off Facebook for $300. Turns out they are load range C (why make two versions of the same size?) but I bought them anyway because they were under priced.

Sold them the next day for $400.

Cleaned out the brake reservoir as best I could, filled with fresh fluid. Un-seized all the brake bleeders, flushed the entire system well.

The right front brake pads have about 4mm pad remaining compared to 8mm everywhere else, the sliders/pistons/pads all move freely though. So $20 insurance/best guess I did the brake hose

Drained and filled the power steering system with the expensive good stuff, it was a little noisy in -20 deg weather.

Also did the rear diff oil with some fresh 75w90 synthetic.

Spent a bunch of time trying to scrape and hammer out all the rust flakes from inside the cab corner area. Used some rust converter+sealer, then self etching primer, then Tremclad oil based gloss black spray paint. Hopefully that slows the rust down for many years, the outer cab corner layer is still very solid. Pic from after primer:

I gave the insides of the outer rockers the same treatment of self etching primer and gloss black rust paint. Doesn't seem to stick as well as I'd hope, not sure if I just have to bite the bullet and use a 2 part paint to get anything decent or what. Also got some weld through primer and went back over the areas I ground down to weld. Plan is to go back in there with a 360 deg straw and coat everything with fluid film or cosmoline once it's closed up.

Got maybe halfway done tacking the top seam, then ran out of gas.

Found another set of tires on wheels, this time 265/75/16 K02s. Wheels are corroded but still nicer than mine, tires are lower tread than I hoped. Paid $675 for them, might end up replacing two. They don't have very even wear, and if I replace two that gets me a newer spare in the matching size.

Definitely looks better with the larger tire.

Still undecided what kind of final finish I want for the rockers. Paint from a rattle can doesn't seem to stick well enough.  Black undercoating looks okay and is easily touched up in the future, but looks worse the higher up the side it goes. Colour matched raptor liner like what I did with my white truck is nice, but pricey. I'd like to thin it down if I were to do it again and get a smoother texture. Real 2 part automotive colour matched paint would be interesting too, something I haven't tried yet but worried about colour match and longevity. Will look a little funny too on the drivers side, with the drivers door being not exactly the same colour. Really the whole truck needs paint, but if I'm going that far I need a less hammered out box. I'd love to hear your opinions and suggestions on how to finish it, and what products work well!

In reply to Run_Away :

I have ordered spray paint from Automotivetouchup.com on several occasions and its always a fantastic match and holds up well.  I sprayed an entire front fender and after a few coats of clear and a buff you couldn't tell it from the door finish.  Using several layers of clear it should work well for your rockers.

Fully welded the passenger rocker

Ground it all down

There's still some pinholes, especially on the plug welds from below. Not sure if I want to use any filler, or maybe some sort of glaze? Maybe like a JB weld type product? Still planning on flooding it all from the inside with cavity wax. I was thinking of doing that last before paint, to make sure the paint sticks properly at the edges.

Had another expensive Rock Auto order, got a cab corner, some exhaust gaskets, rear shocks, front impact sensor, oil pickup tube, oil pan gasket, and transmission fluid. The oil pan gasket arrive damaged from being shipped with the heavy shocks bouncing around, but they're shipping me a new one.

Impact sensor was $150, but peace of mind that I'm not going to blow the bags using a junkyard part, or get another bad one. No more airbag light.

New rear shocks. The one on the front side of the axle was bashed up pretty bad and made lots of noise.

Lent it to work for the scrap run. 2280lbs in the back, just squatting a little.

Just seeing this thread now. For the pinholes I would go over ever welded part with short strain fiberglass. Provides good waterproofing, gets in the pinholes and it's tough. Por15 is probably the best overall product that will etch in and last. Rust repair is almost impossible long term. 
 

cavity wax is excellent 

In reply to Norma66-Brent :

Yeah I'm doing most of this with the thought that I may be going back in here in a decade or so (provided I still have it then).

Cut everything on the drivers side out, got a little carried away.  I'll probably just weld the outer rocker skin directly to the cab corner rather than replicate the layering the factory does, because I don't want to try and replicate those curves and I don't want to spend $250 on the full stamped rocker vs my $70 2D folded repair panel.

Welded in the rear section

Then moved to the front half. The little welded nuts for side steps or whatever are right on the center line, so I had to cut around them

Got the repair panel cut out and I'm about 95% done fit-up. Hopefully welding it up tomorrow or Tuesday. Then the cab corner  goes on, then the outer rocker

Long time no update!

Left front inner rocker was welded in, primed, and painted

Support for the inner cab corner area that is no longer present. Lots of rust converter work here before painting

Left cab corner fitted and welded

Left outer rocker welded on

Welded the cab corner directly to the rocker. Normally the rocker dips inward and continues on to the rear cab wall, but I got the 2D bent cheap rockers and not the fancy 3D stamped full rockers. So to emulate the right hand side, I built it up a little and made a similar dip.

Pulled the bed off because I couldn't get a good angle for the inside of the cab corner. Found a few bed crossmembers packed with dirt, cleaned them out and made a huge mess

All the cross-members inside are nice and solid, no surprises there. There is one chunk of brake line that was encased in dirt that I'm a little worried about

View of the chicken E36 M3 welds because I couldn't get a good angle on things before removing the bed

Cleaned up

Seam sealer

Re-did the seam sealer on the right hand side too

So next up is cleaning up the doors, and maybe a little work on the wheel openings. I keep going back and forth between leaving the bed totally alone vs fixing it up a little. If I was straighter I'd fix it, but it's almost too dented up to be worth putting effort into. I'd love to buy a straight one to fix up, but then that would end up snowballing into a full paint job.

Speaking of paint, I dug out some epoxy primer left over from my K1500 fix up project in late 2019 I assume it's no longer good to use? I did stop by Princess Auto (like a Canadian Harbour Freight) and grab a 1.8mm paint gun on sale for $38