My 1980 Sierra LWB build

[C15_Sierra]

Well, she's not going off a cliff today, put on the new filter, and filled up with oil, and it ran without puking everywhere. So I drove it on the lift, and she's at the shop now getting an exhaust put on.

I'm going with true duals (my Schoenfeld LS swap headers are already installed), 2.5" piping w/ H-pipe, Flowmaster 40-series with turndowns behind each rear wheel. I'm excited!

[C15_Sierra]

Teaser pic

[Pop's C-10]

verdy nice..

[C15_Sierra]

Thanks! And it sounds a lot quieter too. I was able to hear why I wasn't getting any power assist from the booster....haha!

[68 TT]

I have had a couple brand new oil filters leak at the crimp seam. One was a high dollar filter so it isn't limited to cheapo filters as a problem.

You could also be leaking at the oil pressure sensor boss adjacent to the filter that most people tap for a mechanical oil pressure gauge.

[C15_Sierra]

Thanks for the info, 68_TT! I checked the boss, no leak, so must've been the filter.

In other news, got the new brake booster ordered - coming in next Wednesday. Did a systems check today, my thermostat is no good. Rookie move - not replacing the thermostat on a used engine that has now sat for almost a year...

[C15_Sierra]

Well, I replaced the thermostat today, and I still don't have any flow, so I guess its the water pump that needs replacing...to be continued

[C15_Sierra]

Whoops...didn't fill up the block before running...water pump is fine. Now it holds a nice steady 197*

[C15_Sierra]

Also forgot to mention that as of 3/7, it's been 1 year since I've had this truck. A lot has changed since then, for me and it, and while it still hasn't seen the road much in that one year...it has a great road ahead of it!

[C15_Sierra]

Here's a clip with the exhaust ON...that blowing noise is my brake booster...getting replaced later this week


Not a cold start, because I was topping off the coolant and filling the trans earlier, and took it for a little spin. Couldn't seem to get out of first gear, and I still am throwing a bunch of transmission codes. I have to diagnose to see if it's a wiring issue (which it sounds like it is). I don't think it ever got out of first gear...thank goodness for 2.73's!

[Low84]

Sounding real good. So close to having it on the road. What's left, just the transmission issue?

[C15_Sierra]

Originally Posted by Low84

Sounding real good. So close to having it on the road. What's left, just the transmission issue?

There are a few other issues to get it driveable, and then some small projects here and there (I say that now...) to get it to where I want it to be at this stage...

The issues are:
-CEL for MAF sensor too low - may be due to the brake booster leak, I'm waiting for some free time to do that
-Multiple transmission CEL's, may be due to a bad connection somewhere, I have to get all that electrical loctite nastiness that's in the connectors and check voltages to see if it's an electrical issue or if it's a trans issue.
-May have a stuck caliper. When I took it for a quick spin, it pulled to the right (didn't do that before the swap) so I'll spray down the calipers to see if they're stuck

Then after that, I'm going to do up the interior, put on some rallys, and hopefully some 3.73's. Bodywork may come in the fall or next spring. Yep, I'm close

[C15_Sierra]

Replaced the booster last weekend. Brakes are good and solid (if not a little touchy)...Brake warning light is still on, I have to do some further investigating as to why...

Fixed the MAF issue - loose ground wire in the harness - now it runs like it should (it ran earlier, but the ECU "defaulted" to the MAP sensor

Still fighting to get the trans out of default mode. With all the trans codes that I'm throwing, it HAS to be a bad ground because I have power to the trans :argh:

[C15_Sierra]

Well, my 4-on-the-floor is back. Trans plug was not fully seated, and so the harness-side plug was not fully seated on it.

The 5.3 with the flows has got quite a good voice, trans shifts nice. I'm looking forward to having some fun!

[C15_Sierra]

3/25/12 Update - slowly, but surely making progress...(excuse the mess in the cab)



Backing up to last weekend, I installed maroon seat belts from an '87 K2500 that was junked. They fit fine, the plastic sheathing was already broken, so they fit with the '80 seat. My old ones were too faded and warped, and one of the seat belt covers was broken.

Here's how she sits today...







I reinstalled the headlight covers. I need to buy new grille retainers so I'm not installing my grille just yet. Plus, I'm deciding on what color scheme to refurbish it with or install a billet grille. I only have 3 hubcaps, 2 of which I put on the front wheels, still have to put the 3rd on. I like the look of them, but I'm sticking with the refurbished rallys I have







I also swapped steering wheels this weekend. It's from a '88-94 C/K, and even came with a GMC center, which I got for free-99. I'm strangely liking the look, even though the wheel is a bit rough, and I'm considering going to the yard to pick up a leather-wrapped one. At first, it was cool to have the thin-rimmed one, but I like the feel of the new, thicker wheel.

I also finished up the shifter install, took a little longer than expected, and I'm gonna have to take it apart again when I order carpet. It came out pretty well, and it looks better than the bare shifter mechanism look it had been sporting before.

Next month's steps are gonna be a CT reg, tires on the rallys (255/70/15's probably), and an interior re-do.

[Kerlijah]

Makin good progress man, keep up the good work!

[C15_Sierra]

Haha I wish it was good work...broke down on the way home from work (on the highway, no less), and so far all I know is there's a short somewhere on my engine harness, which keeps blowing one of the fuses. I have to go back and re-trace my wiring harness and see what's going on. I also may bump up my harness redux project (just bought a 5.3 harness on evilBay last week) so I can avoid this again.

Edit: Removed the fuel pump relay and the ECM isn't blowing its fuse, so it's the fuel pump

Lesson learned - wire the fuel pump in its own fuse for my "round 2" harness

[C15_Sierra]

Final diagnosis is that my fuel pump wiring wasn't sufficiently tied down and the excess fell down onto the exhaust and melted onto it, shorting out the circuit. Will repair and adequately tie it down next time!

[C15_Sierra]

I repaired the fuel pump wiring and it ran for another week. I went to fire it up yesterday, and it was running rough and backfiring (slightly), and found that fuel pressure is running low...so I may have hurt the fuel pump, and even though people have run the same EP241 pump (used in Camaro/Corvette TPI applications) that I am, I'm thinking I need to run an EP381 pump (used in 350 Vortec trucks)

So, for now, I'm gonna park it until I get the new pump installed

[C15_Sierra]

So, 6 weeks later, I still haven't replaced the fuel pump. Why? A combination of getting a little burnt out from auto/house projects, a little phobia (bees have started nesting...and I hate bees), a little frustration that this $#$%^$% won't run right.

I have the EP381 sitting in a box on my kitchen counter, and I've run into the dilemma of how to change it out. I still have ~10 gal. of gas in the tank, so dropping it will be a PITA. I could take the bed off and change it but I need to borrow a engine hoist (I don't have friends lol). A friend has one, but I'd need a truck to pick it up (it doesn't fold) - it would be nice if mine worked!

And to top it off, since I haven't started it in 6 weeks, the trans decided to start leaking all over the driveway. I guess the converter finally drained its way to overfilling the trans pan, coupled with sitting in the sun. So now I have that mess to clean up. Naturally the battery is dead and I can't prime the engine to start b/c there's not enough juice to run the pump - and since that's the case I didn't bother turning it over last night. Gonna have to wait till it stops raining to throw it on the charger and see how well it runs now. I just want to move it back into my garage and forget about it

Thought about selling it but 1) I have too much time into it to do that and 2) it just doesn't feel right to just stop. BUT I've come to the conclusion that its gonna take a lot more time/money to get it to where I want it, mainly body/interior/drivetrain work. So, with that said, I have two options: park it and slowly work on it (hopefully keeping it driveable so that I don't run into trans issues like this again), or sell it, which frankly, I don't know if I'd be able to sell the truck for anything NEAR what I have into it (not new news to me, but still sucks)

Anyone else lose motivation on a project?

[C15_Sierra]

Here's my list of things that I'd like to get done:

-Tires - 255/60-15's on re-painted rallys w/ new center caps (have the wheels/caps, just need tires)
-Gearing - have a 2.73 in there right now...way too tall for OD, so I want to put 3.73's back there. I had the computer programmed for those tires and gears. That requires a new carrier (so my research tells me) so I might as well put a posi back there if I'm gonna do that, but it's mo' $$ (and we all know what comes after that...)
-Interior - Seat needs bottom foam replacement (have another '80 bench for that), and re-upholstering (I have that too). Also needs insulation (don't have), carpet kit (don't have), door panels (DO have), and a radio/speakers.
-Exterior - Needs a paint job, windshield, dent repair, new front and rear bumpers, possibly new hood (kinked a little, if you can see from the pictures), repaint the grill, paint the headlight surrounds black/gray, new side view mirrors, and tail gate. Thinking about side moldings as well, since my truck didn't come up with those. If I can find some good Sierra 15 emblems I might use them, I think mine are too far gone to be saved (maybe I'll black them out or paint them myself)

Seeing this list kinda de-motivates me a little bit...

[C15_Sierra]

Got back on the Square Horse today and replaced the fuel pump. Only took an hour...what was I waiting 5 months for?? Couldn't fire it up because the battery is dead and I had other things to take care of. Maybe tomorrow.

Over the past 4 months, the truck has sat outside my house, close to the road, and I've had a couple people come by and ask if it was for sale...had it on Craigslist too, with only a couple bites. I just didn't have the heart to fully talk the beast up to sell it, so I'm slowly getting back to working on it. The original working list above still stands, plus I have to register it in CT now that I let my TX reg expire on it.

I'm thinking I may add a little bit of lowering to the mix to give it a little flair. I've found my little Cherokee to be capable of hauling what I need to haul in the meantime, so the truck can be transferred over to do a little show duty. I need paint badly, but the local scene is all about rusting their hoods as well as other "patina" so I fit in pretty well as it stands

More updates as I get 'er back on the road...

[C15_Sierra]

End-of-year update:

The GMC is still with me. I last ran it sometime last winter, then suddenly it didn't want to run or idle. Having been de-motivated (again), I focused most of 2013 on my other activities: house projects (re-did gutters, deck renovation, general cleanup/weeding), autocrossing my '94 Miata, and a new job that has me commuting a lot more than my previous one.

I put the GMC into the garage sometime in the summer (bribed a few friends to help push it in as I couldn't get it started) and took apart the rear end to install 3.73s. I bought another 12-bolt from a 67-72 with 6-lug axles and 3.73 gears, but the ring gear was pitted on 1/5 of the teeth (I knew that when I bought it - I bought it for the carrier), and a new set of gears from Randy's Ring & Pinion. I disassembled the old carriers, pressed new bearings and installed the ring gear on the new carrier, and that's about as far as I got before life got in the way again.

Last week, I was finally able to get back in the garage for some quality time. I'm going to finish up the gear install in the coming month, as well as finish up the poly cab bushing install. I have some sound deadening to lay down in the cab and a carpet kit on the way. Last winter, I replaced the bench seat lower foam from the parts bench that I bought a couple years ago, and re-upholstered it in red cloth. Its currently sitting in the basement until I get the truck out of the garage and install the carpeting. At that time, I'll reinstall most of the interior, including the dash pad and yet-to-be installed door panels, which I might have to re-paint as they're a brighter shade of red than the rest of the interior parts that are going in.

I still need to get it painted, something that I had planned to do with my newsed 60-gal Craigslist air compressor that I got this past summer. In talking to a HS buddy of mine during the holidays, I may just register/insure the thing and drive it down to his dad's shop (about 1.5 hrs from my place) and have him paint it. I have been back and forth about selling the truck, but I can't come to terms with parting with it just yet (despite my multiple breaks from the project) so I am pushing towards completion so I can get back to driving it.

Oh, and I mentioned something about it not running anymore. Well, I took off the bed when I put the truck in the garage, and popped off the fuel tank sender. I pumped out about 5 gal of fuel and, to get rid of it, mixed a little bit of it in with the fresh fuel in the tanks of both my other cars (a '94 Miata and '13 VW Jetta). Well that little bit was enough to poison the tanks of both of those cars - the Jetta had to get towed for the repair (it was the quickest way to get back on the road - I've got a 50 mi one-way commute to work every day) and the Miata had to sit for a few days until I had the time to flush out the tank and change out the fuel filter.

Anyway, my conclusion is that I still had fuel in there from a while ago (April 2012) that I don't remember if there was any stabilizer in it (I was driving the truck around at that point) and that had been mixed in with fuel that definitely did have stabilizer added (around Nov/Dec 2012). Since we only have ethanol-infused garbage here in CT, the fuel in the GMC caused it to run poorly all of a sudden (after the merely-tolerable stuff was burned off).

In addition, the moisture rusted the inside of my new gas tank. The plan is drain the rest of the fuel and brush out as much of the rust as I can. Or would it be best just to buy a new gas tank?

Hopefully, I will have this junk back together by the new year, and by spring it will be in good enough shape to do some Home Depot runs.

[C15_Sierra]

Some shots of what I have working on and what I have down the road for this truck:

I've mentioned before that I'm re-gearing the truck. The truck originally came with a 12-bolt rear, I'm not sure if it's original to the truck, it's a 2.73 ratio. It looks like it hasn't been apart, but the truck was a factory 250 I6/3-speed manual truck, so I would have thought that it would come with a higher-geared rear end. I suspect the 2.73's were put in to take advantage of the 305/TH350 that one of the PO's put in around 1988 (according to the PO's notes).

Anyway, I bought a junk 12-bolt and took the carrier out of it, and bought a 3.73 R&P and bearing kit from Randy's Ring and Pinion. Currently in the middle of setting up (I have a friend who's supposed to come by and help me finish)

When I took the old carrier out:


Awaiting final setup. I also got bored one night and painted the exhaust black with VHT paint


No-name sound deadener from evilBay:


Carpet laid down. I had the heat going in the garage to help it settle. I'll give it a few days until I go over it again and find where to cut holes for the seat belt mounting holes, bench mounting holes, and the shifter.



Last winter's project was to replace the bottom seat cushion foam from the parts bench and reupholster the whole thing...came out pretty good!


Front fenders were removed to install cab bushings. Install went pretty easy on those. I'm taking the emblems off in preparation for bodywork/paint


Another shot of the 5.3


Shot the grill with a couple coats of Argent Silver. Need to go down to the hobby store to find a suitable match for the GMC emblem paint


Front left fender removed, and my arsenal of tailgates. I have the original, on the right, which I'd like to use because of the centered GMC logo that is impossible to come by in this shape for cheap. It has a few major dents in it, I want to see if its salvageable. If not, I picked up an '87 GMC High Sierra tailgate (with the Fuel Injection label) with no rust on it. I pulled the seatbelts from the same truck.


I'm going to replace the cracked plastic/foam wheel with a leather-wrapped one I found in the junkyard...also happened to come from another '88-'94 GMC truck



Old man damage from the PO






Front bumper needs sandblasting and painting, but I have thought about just buying new chrome ones


Rallys got a coat of argent silver 2 winters ago, and I had them outside for a bit, hence the dirt. I have original metal GMC center caps that I will be replacing the emblems on (free from my old boss in TX from his '84 that got an LS1)


Misc. parts on my bench that will go into the truck - the original bezel, maroon pillar trim that I pulled from a junkyard truck, and a spare 5.3 wiring harness in the box


A shot of tire central, and my soon-to-be office furniture (from a '92 Audi). None of those fit the truck unfortunately. Under the bench, peeking out, is the original-condition patterned vinyl upholstery from the parts bench, which was from an '80 K10 Custom Deluxe. The same pattern was in my truck, but red. Gonna figure out what to do with that one...


Urethane dash pad replacement with the original trim waiting to be re-installed


The rest of the poly bushings for the suspension, and sway bars if I end up putting them in


Hiding under a bunch of boxes and my Miata convertible top frame are the door panels that will be going into the truck. The original one that came with the truck was toast.


6x9 speakers and brackets that I pulled from a junkyard truck will be going in before I finally lay the carpet


Summit boxes with hard lines for fuel that I'll be using on my other project (as well as brake lines for that car, as well as a replacement seat) and stainless fuel hoses for the engine bay of the GMC. Should have done that the first time around but hey, live and learn.



The reason why I've got renewed interest in getting the GMC out of the garage is in the foreground. It's a 1987 BMW 535is that I'll be doing a 5-speed swap on and cleaning up the interior to become another driver/project. Only 118k miles and minimal rust. The rest of the fleet is outside as well...

[83 Silverado]

Cool project, this going to make a nice driver or tow rig for some of the other drive way toys.