“I Just Got An Amazing Deal One Of The Greatest American Pickup Trucks Ever” I wrote earlier this week after spending under $5000 on a 129,000 mile, four-wheel drive, manual transmission, rust-free GMT400 pickup — a Chevy K1500. Now I’ve owned the truck for a couple of days, and while I love it, I also think that maybe I didn’t get as good of a deal as I thought.
The first thing that got me is something that I didn’t think would be such a huge deal. During my test drive, maybe I did notice there was a bit of input shaft bearing noise when I was off the clutch, but how expensive could a new NV3500 five-speed transmission possibly be? They’re a dime a dozen.
Unfortunately, I was mistaken. It turns out that early the NV3500 only went into GMT400 trucks in 1993; prior to that, these trucks were equipped with a dastardly Getrag five-speed — the 5LM60, also called the HM290.
Transmission Digest — a publication devoted to the transmission repair industry — has a whole page on the HM290/5LM60, and it’s bleak.
“The HM290 was by any standard an extremely complex unit that most technicians considered time consuming and difficult to work on. The unit requires some essential tools, available through Kent-Moore, without which working on it is all but impossible.”
[…]
The 5LM60 …uses the overly complicated and cumbersome four-rail shift design with its myriad number of parts. In 1993 the 5L60 went through further design changes and was designated the New Venture 3500. At long last the four-rail system was scrapped and replaced with a single-rail
Someone on Car Junky automotive forums claims to have been a trained GM transmission technician, and he/she also has very little good to say about the 5L60:
When I received training at the GM training center in Minneapolis in 1991 on this transmission. The training manual (which I still have) refers to it as a 5LM60 Formerly HM-290. At that time I was told the transmission was currently being built by New Venture gear and New Venture Gear is a joint venture between GM (Muncie transmission) and Chrysler (New Process Gear).
In 1987 it was referred to as MG-290 My guess is the G is for Getrag
In 1988 it was referred to as HM-290 HM= Hydramatic / Muncie
In 1989 it was referred to as 5LM60
In 1991 it was referred to as NVG 5LM60 NVG= New Venture GearThere are two designs for the input shaft, input shaft bearings and main shaft bearings. The first design, which documentation will show as 1988-1990, had a ball bearing and a roller bearing behind it. The second design only has a ball bearing but it was a much larger bearing. The first design bearings were more prone to fail. They were failing when these trucks were under warranty with very low miles on them.
There is no way I would suggest fixing your transmission. The bearings are very expensive. Last one I did an estimate on, it was over 2 hundred just for the GM input bearing. The input shafts are different so you can’t put the better bearing in the earlier trans. Also if you take apart the main shaft, many of the parts cannot be reused, and you need an oven and melt sticks to heat the parts to the correct temp for pressing them together during reassembly.
A large holding fixture (special tool) is used to hold everything in position when assembling the transmission.
It is almost always less expensive to replace these transmissions then it is to rebuild them. Even in parts prices alone. It is hard to find good used ones.
But that’s on me; I should have looked at that odometer when I was test-driving the truck, and I should have done a bit more research into the different transmissions of the various K1500 model-years. Alas, it’s my second recent California car-purchase blunder, and while I still don’t think it will lose me any money when I resell, it is a bummer.
The rest of the truck is in good shape. There are a few loose bolts holding the transmission crossmember to the frame, but I’ll just tighten those. The AC leaks at one of its Schrader valves, but I bought a tool to fix that without having to evacuate the refrigerant:
And the headliner is shot:
And the radio makes loads of static
The biggest issue is the odometer (which I can fix easily) and the transmission. If I can get the transmission replaced for a reasonable sum, I honestly won’t care that much about the odometer. Sure, the truck’s value took a hit, but as far as usability, this GMT400’s motor seems healthy, the frame is solid, the body is straight, and pretty much all systems are a-go except the transmission input bearing and the AC.
It’s still a good truck, but just not quite the deal I thought it was.
Don’t make mountains out of molehills. You have a transmission that makes a little noise under certain conditions. It will probably go on for 100K more miles like that – how much are you actually going to drive this thing? You certainly aren’t going to be commuting in it given what else you own… Drive the thing until it doesn’t move anymore and don’t worry about it. If it sounded like a rock crusher or a siren going down the road and needed three hands to shift I would be nervous, but not with what you have going on. Change the tranny oil more often. Maybe try a little heavier oil since you live in a warm climate. It might not even BE the input bearing, I had a throwout bearing make noise like that in one of my cars. Fixed it when it needed a new clutch anyway.
The odometer? Who cares? It’s an old truck in decent condition that you got for pretty cheap. These things go for a gajillion miles if you can keep them from rotting out, and yours is from the desert. Perfect! Fix the headliner, throw a new stereo with BT in the thing, fix the other minor issues and enjoy the hell out of it.
The Radio is probably the CDM “control data module” fancy term for the actual remote mount tuner, under the dash is prolly failing from bad capacitors. I fixed a buddy of mine’s very clean & original ’90 C1500 with the CDM stole off a Delco CD player radio from an early 90s S-10 I had in some extra parts. Had a broken CD drive as all of them do. If you want to keep it factory look for the least expensive of either another CDM for an ‘88-‘94 or one robbed off of any of the more conventional 1.5 DIN Delco tape or CD units of same vintage that had the rocker switch bass and treble controls. Those also had the same module just mounted on the radio chassis instead of remotely. Swap a couple brackets on and it fits under the dash too.
Of course you can always just mount an aftermarket unit where the cassette player goes and get the aftermarket storage pocket for where the current radio display sits.
Edit, ‘90-‘94. Just remembered ‘88-‘89 had an older style connector for the radio IIRC
They really are decent machines, but not invincible, sadly. I’ve put a fair bit of sweat and money into my K2500, but it’s still an old machine that needs attention. Wouldn’t ever part with it, though!
The radio is a pretty common early GMT problem. My ‘88 did the same thing. As I recall, the amplifier is actually down in the dash somewhere and is prone to failure. I never replaced mine but if memory serves a single-DIN (or double? Don’t recall offhand) replacement will fit and then you can bypass the amplifier altogether.
DT: you need to make a check list (and use it) when you go examine a car for sale.
Yeah, no kidding – I’ve bought plenty of junk vehicles, but I’m not about to spend 5K on anything without being pretty dang careful – and I’m not even a professional car buyer/writer/journalist!
The truth is: I didn’t really care that much. A rust-free 5spd 4×4 Chevy pickup for $4,900 is a solid deal. It’s just not QUITE the deal I thought it was initially.
“Here’s Everything Wrong With My GMT400 Chevy Pickup – So Far“
It was under $5K, it’s *rust-free*, straight, and presentable looking. It even runs decently. Nothing else really matters and is just wrenching. It could be showroom-looking with not a single issue when you look at it, and it would STILL puke something up within the first few months. The way of old vehicles.
Where I am, one of these beat to shit with 200K on it is nearly double that. Easily. And up north every fastener underneath will be lumps of rust, even if you luck out and the frame is solid. Making doing anything absolute and utter misery. And it will cost just as much – and you can bet the A/C won’t work because the salt will have rotted out the condenser and all the lines. This thing was a steal even with the issues.