Picked up a 1990 GMC K1500 back in October 2020 down in Georgia. I’ve been wanting one of these trucks for a while, my dad had a 1988 when I was a kid and I have lots of good memories riding around in that truck.
I’ll document the restoration in this thread, enjoy!
I am also making videos of a bunch of the projects along the way, subscribe on YouTube to follow along: https://youtube.com/playlist?list=PL0Ed4Frz6sP_9Pq0Hgk6nwdTYOEoFLz51
The day it arrived at my house:
One of the first things I did was remove the “fear this” window sticker and the broken rain guards.
Nice solid looking truck to start from.
Looking forward to the thread
First attempt at trying to address the soft brake pedal that I noticed when I first looked at the truck was to replace the master cylinder. The pedal is a little better, but something else in the brake system is still not right.
YouTube video for anyone interested: https://youtu.be/v48v_ZTJpQg
I love this gen short/short/4wd. A little lift and a little tire and it's all good.
Second attempt at trying to address the soft brake pedal. I started out just wanting to adjust the rear brakes but after seeing the cracked rear shoes, I went ahead and did a brake job on the rear (drums, shoes, wheel cylinders, hardware, and rear brake hose). Pedal is better but still not where I think it should be.
I've never seen shoes cracked like this before:
Nice new brakes!
YouTube video: https://youtu.be/ngPODfdifxc
Third attempt at trying to address the soft brake pedal. After lots of reading, I’m starting to think the rear wheel abs unit is the issue, specifically a leaky dump valve allowing fluid to leak into the accumulator rather than apply pressure to the rear brakes. This is a great article describing the operation of the rear wheel abs system:
https://www.aa1car.com/library/abs_kelseyhayes_rwal.htm
I also noticed that my combination valve was leaking a little bit of fluid out of the metering valve so I decided to replace it along with the rear wheel abs unit. Unfortunately, the “AC Delco inspired” combination valve that I purchased started leaking brake fluid out of the electrical connector on top about 2 minutes after I installed it and the brakes are now probably worse than where I started. Nothing worse than crappy cheap parts!
Currently sourcing a used combination valve to replace this crappy knockoff valve. The brakes will have to wait until the new valve arrives.
YouTube video: https://youtu.be/Beezi0ch4C8
Mr_Asa said:Nice solid looking truck to start from.
Looking forward to the thread
Thanks! I was specifically looking for a southern truck so that I did not have to deal with too much rust.
AngryCorvair (Forum Supporter) said:I love this gen short/short/4wd. A little lift and a little tire and it's all good.
I should be able to fit 32" tires under it with the stock suspension. I'm thinking some BFG all terrains with the white letters facing out!
One of the other things I noticed when I test drove the truck was that the steering column was a mess. Turn signals would only latch in one direction, gear shifter return spring was broken, and the horn did not work. Dug into the column and ended up replacing quite a few parts to get everything working right again:
- Turn signal cancel cam
- Turn signal switch
- Wiper switch
- Turn signal lever
- Gear shifter return spring
As a bonus I found someone selling new old stock GMC horn pads on eBay so I picked up one of those as well. It’s nice to have all of the stuff right in front of you fixed!
YouTube video: https://youtu.be/iKlprGHcoVE
Next up was to start addressing some of the oil leaks on this truck. The front differential was leaking really bad and looked like a good place to start. I pulled the differential and took it over to a local shop for new axle seals, pinion seal, and a re-seal on the case itself. Went ahead and added a new 4wd actuator and vent plug as well.
Nice and clean differential ready to go back in the truck:
YouTube video on differential removal: https://youtu.be/5heaP8rlivU
Engine oil leaks, where to start! Well, I suppose you just start at the top and work your way down! Pulled the intake manifold to replace the gaskets. Went ahead and added a new EGR valve, throttle body gasket, heater hose quick connect, and temperature sending unit.
I have to admit, pulling the manifold was a much bigger job than I imagined.
While the valve covers were off, I went ahead and replaced the valve seals to hopefully fix the oil burn at startup. The original exhaust valve seals were pretty much gone so I’m feeling good that the new seals will solve the oil burn at startup.
YouTube video on valve seal replacement: https://youtu.be/CBK6ACbvF9c
Oil pan was up next. This project morphed into replacing the timing cover gasket as well since there is some interplay between the oil pan and timing cover gaskets and I wanted to make sure I got everything on correctly.
With the timing cover off, I could see how loose the original timing chain was (160k miles), so I went ahead with a timing chain replacement as well. The engine is starting to come back together!
The oil filter adapter is notorious for being a leaky mess on these trucks and mine was no exception. New gasket, o-ring, and quick connect fittings are in place. I’ve got new cooler lines ready to install as well.
I could not figure out a way to get the inspection cover off of the transmission without dropping the y-pipe. Removing the inspection cover was necessary to get the oil pan off.
The slip joint between the y-pipe and catalytic converter was not coming apart so I ended up cutting the y-pipe to get it out. I also broke the end off of one of the manifold studs that holds the y-pipe in place which required a nut to be welded onto the stud to remove it from the manifold.
All new studs are now installed and new y-pipe is in place!
Nut welded onto old stud:
New studs, chased all of the threads in the manifold before installing:
Walker y-pipe:
New water pump mounted up:
Added a new temperature sending unit for the gauge cluster. Previously when driving the truck the gauge would hardly move off of the lowest reading, I’m hoping it was just a bad sending unit...
I decided to pull the driveshafts and drop them off to get new u-joints installed. The rear transfer case seal was a little bit crusty so I went ahead and replaced it while the driveshaft was out.
YouTube video of seal replacement: https://youtu.be/fAFnlLMTQmU
Nice job man! I love this body style Chevy pickup, and they definitely look best in short bed/single cab. This is going to be a great driver.
Back under the hood to take care of some of the loose steering. Installed a freshly rebuilt Blue Top steering gear and Moog pitman arm along with a Moog idler arm.
Noticed the tensioner pulley was a bit loose when I pulled the belt off. New AC Delco tensioner pulley installed.
Had a day off this week and I was able to make some progress on the truck. Freshly painted valve covers are back on and a freshly rebuilt power steering pump is installed. I sent my original pump out to powersteering.com for the rebuild.
Got my new heater core installed last night and did another YouTube video on the install:
Did you stick with the factory ratio or the quick ratio? Curious as I have a 1990 2wd 1500 im slowly trying to make nicer.
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