Ive owned multiple generations of Miata and now a GMT400 hence the title.
Backstory: I have an 03 Dodge Ram with 360k miles. It has been the most reliable truck Ive ever owned. Unfortunately it is a 2WD and a 4.7, and its getting difficult to find parts that arent your run of the mill service items. I needed to recover the drivers seat last year and according to my upholstery guy and the local dodge dealer, I got the last OEM seat cover in the nation. I think no big deal Im working on a 17 year old truck thats just the way it goes. A few weeks later Im working on my dads GMT400 Suburban, I go to removed the headlamp switch and the bracket that holds it has been broke and glued back together, I think "Damn Ill never find one of these for a 27 year old truck." I do a little research just to see if its out there and the local Zone has an ACDelco in stock for like 7 dollars. That got the wheels turning. I thought Ill always be able to get parts for a GM truck with places like LMC, GMs support and all the people modifying all the different generations. So last year I started look for a GM truck. Originally it started as a TBI, Vortec or LS, just buy the nicest one I could afford. I realized the GMT400s have been going up in value the last few years and I was going to be hard for me to swallow paying the premium for a TBI truck which would immediately needed to be modded to not be a slug and do what I want it to do. Then I was looking at vortecs and LSs. I had a 96 Vortec 5.0 Z71 in high school and Ive regretted selling it ever since, so I decided to just look for a nice vortec 5.7 truck. That brings up to about 6 months ago. I was looking almost everyday I missed probably 7 or 8 of them, with a couple being sold right out from under me. It got to the point where if a clean one would pop up, I would just message the seller "I have cash in hand, I will pay full asking, when would you like to meet." I remember not being able to give mine away 10 years ago, and now there were selling within hours of being posted. Tuesday i had arranged to pick one up for 5K. Had 182K miles and was spotless. I showed up at the arranged time and he sold it to someone else. I kept looking and was seeing clean ones in DFW on car lots for 13-15K for a ECSB Z71. So i decided they are too hot here and needed to look elsewhere and up my budget a little. I checked all of Texas, Oklahoma, Arkansas, Louisiana, and New Mexico. I found one Weds in AK, for 7K. It looked really clean. Ad said it was clean, but had clear peeling on hood and roof. Its 90s GM white paint so no surprise. We make arrangements and he agrees if he has it Fri night he will hold it until I can get there Saturday.
So we head out 7 am Saturday, get to Texarkana about 12 and check the truck out. Im expecting terrible steering and brakes, you know the GMT400 trademark, oil leaks, who's seen a gen 1 SBC that doesn't leak oil, and a myriad of other GMT400 common problems. The truck actually looks super clean. The clear on the hood is worse than expected, but the color hasn't started coming up so at least its still all white and doesn't have the speckled look most of the white ones do. Its pretty dry under the car which is surprising. Pretty much everything works except the AC is only cool. I jack it up to shake the front end down and its not terrible. So we go for a test drive and it has the best brake pedal I've ever felt in a GMT400. Its drives and runs nice, so we go back to negotiate. It has terrible tires and he tells me it had an o2 code, which I verified to be a heater circuit code for a downstream, but he had already put a sensor in. He shows me an invoice for 3K miles ago that includes a new EGR valve, plugs, wires, cap, rotor, o2 sensor, fuel filter, and an AC charge. We agree to 6500 and we head back to DFW.
It made the trip with only the slightest hiccup. We hit Arlington, got stuck in traffic and I got 3 or 4 really hard upshifts and downshifts. No check engine light, but I check codes right quick and have a pending P1870. Which is essentially saying something in the trans is slipping. Commonly the TCC. It clears up I keep driving and make it home. I fill it up and it managed 16.5 MPG. Pretty much what I was expecting.
Its a 1998 Extended cab (3rd door) short bed K1500 Z71. It has the 5.7 L31 Vortec/4l60E/10 bolt with 3.73s. It has 138K miles.
Pictures of the truck. Guy asked if I wanted the camper, I said yes assuming its worth something, and I could sell it. Its not my favorite but its growing on me. Matches the old man vibe the truck gives off.
Came from Dale Earnhardt's dealership #doitfordale
Interior is super clean
I did a little research last night about the P1870, some guys are just rebuilding the trans, some are replacing the valve body and TCC valve with an upgraded part, and some are having luck with just a fluid change. I decide to do a pan service and flush today and start there since the truck only has 138K miles. This morning I picked up a filter kit and an O2 Sensor.
Got it in the air, and saw a new o2 sensor.
Oh man. I really dont feel like chasing the circuit and finding the problem. Then I realize thats the bank 2 downstream and the code if for bank1 downstream. Sure enough that one appears to be OE.
I put a little PB on it and it comes right out and I put a new one in.
While it was up I gave the front end a better shake down and surprisingly the only loose part is the idler arm, even the idler bracket is tight. I had already planned on a front end rebuild, so Ill probably just do the whole steering linkage anyways. Right now the plan is proforged or the mevotech TTX line for the whole linkage with solid tie rod adjuster sleeves. Eventually I plan on the jeep steering shaft (ujoints instead of rag joint), redhead gearbox, k2500 forged lower arms with press in ball joints (stock is stamped steel with riveted in joints), new upper control arms, and bilsteins shocks. On that note, surprisingly it already has billies on it. Ive seen them on a few other GMT400s but not many.
I flushed the trans. Fluid was dark but not terrible. It always looks worse than it is in the machine.
Then I drop the pan. There was some clutch material but it didnt seem excessive to me.
Inside the trans looked pretty clean
I put a a new filter and pan gasket on and filled it up.
Next I checked the brake fluid.
It looked terrible. I was going to do a full fluid change but I plan on doing the GMT800 master swap anyways and the brakes are great the way there are so I didnt want to mess with them too much. I was aggravated that there was so much grime in the reservoir that you couldnt see how much fluid you had with the cap on. So I sucked out the reservoir and wiped the inside down and refilled it. No after picture because the fluid was immediately black again. I can see throught the reservoir now, so thats nice.
A/C system had about 9 oz, should have 32, no obvious leaks, so I let it sit under vacuum for a while and put some dye in it and charged it. Its working great now. Ill check for dye when it quits working. Im sure its leaking somewhere.
After that I went for a drive and on the first test drive the pending P1870 went away so maybe I lucked out. We will see.
Immediate plans are to get it inspected and transfer the title, then new tires. Ive always advocated for the KO2s, I think a set will run me about a thousand, but through some friends I can get a brother in law discount on the Bstone Revos or Fstone Destination AT2s and save three to four hundred dollars.. I like that they are less aggressive and I dont. I have to realize this is supposed to be a capable DD. I dont need the most aggressive AT, I need it to drive nice and quiet, but personal experience is The KO2 is very well mannered for how aggressive and capable it is. So Im torn. Replace all the steering linkage with uprgaded parts, and in the near future is an MPFI conversion. It has a slight rough idle, nothing crazy, but Ive seen a spider fail and dump fuel and take out a main, so I dont want to leave it too long.
