1994 Chevy 3500, 6.5 TD. 136K on the clock. What do we know about them.
Doing some reading says most issues are operator error. Leave it stock, maintain religiously, run a lubricity additive for the injection pump, and move the injection control unit so it won't overheat, and they hold up fine.
Anyone have anything to add?
I've found a 4 door ramp truck, that would be a awesome race car hauler. I'm very tempted.
Make sure the brace is on the starter and that no one has messed around with the bolt holes. I bought a 6.2 non turbo with "starter" issues. That can of worms turned into a gas conversion.
If you torture it, the block will split. Stock power levels, they seldom split anything. At least not every day.
When they were new, they were definitely the weak sister of the big three.
Harmonic balancer is something of a wear item, crankshaft breaks if neglected.
What BrokenYugo said - the harmonic balancers are only good for about 100k and a busted one is a good way to get a new motor.
Avoid ones that are rolling coal, these don't take kindly to trying to turn up the pump.
There are some known improvements that are actually helpful, like a better downpipe, but there is not much power potential on these compared to, say, a Cummins of similar vintage.
Any idea as to fuel economy.
Better than a 350, a lot better than a 454. These were built more for economy than power.
The crew cab dually I had averaged 13mpg ,loaded unloaded trailer empty or full. Always 13mpg. I went to 01 f350 and 21 mpg
I split the block on a stock one a long time ago, it was my work truck when I worked at the crane company, it was the worst engine I've ever had contact with, it was crazy slow in a 3500 std cab tool box side pick up. It got abysmal fuel economy (like 9) then broke in half for no reason. Hilariously bad engine imho.
Not sure on the TD, but my NA would get 20-21 mpg empty on the highway if you kept it under 70 mph. Mixed driving the mileage was around 18 mpg.
Towing a 3,500 lb boat or car trailer would drop highway mileage to 17-18 mpg.
That was in a 1990 reg cab K2500 (8600 gvwr) with 3.73 final drive and the SM465, so no OD. Oh yeah, it didn't have AC (as in deleted when ordered), so that may have affected my economy.
Edit:
I will agree about the harmonic balancer. My truck had around 800,000 miles on the odometer (which was broken) but was on its 3rd engine and second trans. I saw about 275-300k miles before snapping cranks, but I do personally know of one (not mine) that snapped the crank around 100k miles.
The engines were still running well and not burning oil when the cranks snapped (on highway, truck empty), but I didn't know about the balancer issue. I tried replacing the crank on one at 275k miles on the engine, and saw it snap shortly after 300k. If I had know about the balancer issue they might have lasted a lot longer.
Im curious as to this topic as well. I'd like to put one in my 88 chevy 1500 single cab with an old school 4 spd and a tall rear gear.
I have a friend selling a 6.5 suburban. It has never been apart, runs well and currently has 500,000 km on the motor. It has had two injection pumps and a couple pump drivers. Bone stock from day one.
I had a duallie extended cab. I added a Heath chip and a few other go fast parts. It pulled very well but broke a rod at about 250,000 k.
My moral would be that they are decent if you leave them stock, and don't work them too hard. They also get pretty good mileage. But stock they are sluggish, and if you hop them up they will break.
Not particularly powerful, troublesome when modified. A lot of the parts support, at least through GM, is starting to dry up.
I have a '94 K1500 with the 6.5L 315K miles on it. All stock except for a PMD relocation kit. Runs good, though the EGR system is a little funky on mine and is causing a low boost situation.
You're never going to win any stop light drag races with it. But it tows all day without complaining. Carry a spare PMD with you and check the balancer for wear and you're good.
With primarily city driving I get 19mpg. With mostly highway driving I get 20mpg, while towing my car I get 16mpg. I drafted a bus doing 80 from Nashville to Atlanta once and got 24mpg, that's my record.
Don't forget to relocate the PMD to the front bumper and not leave it in the stock location at the intake manifold (where it overheats and causes all sorts of problems).
I had that one for a few years as the tow pig/errand runner. Not very powerful, but it did the job. Didn't get much more than 11 mpg towing as pictured. Would tow up a mountain, just not very fast. Let's just say, though, that that truck was the reason I switched to the 8.1 liter gasser Suburban 2500...
I've got one in my 2000 2500 longbed, it seems like as fine lump. I hate diesels, and don't know a ton about them, though, just for the record :) It rides as crappy as any other truck of its' vintage and people who roll coal or try to race these stupid things are dumb anyway :)
I believe the water pump is going out on mine, but other than that it's not really given me much trouble after a glow plug replacement @ 180k.
Plan on overhauling the 4l80E at 175k or so, or you'll get stuck like I did when the reverse planetary gear decides to not be part of the team anymore. According to the transmission dude that rebuilt mine, the rebuilt/upgraded ones are generally good for around 3-400k use, though.
I got 20ish MPG on my last tank towing a Miata on an u-haul open trailer I think, but I normally get between 7 & 8 because it primarily gets used to plow my driveway and haul gravel & soil around town. It's got the k&n intake and the straight-through diamond-eye 4" exhaust which is sort of bro-tastic embarrassing around town, but it's not too drony on the highway and I'm not spending money to replace a working tube.
Be careful relocating the PMD into the front bumper, the PO of my truck lost one because snow packed in around it and shorted it out one year, so it's now at the top/center of the engine right behind the fan.
Tons of good, not much bad.
I will agree with the balancer issue, but just yank the one you have and install an aftermarket viscous balancer. Its $250 worth of "fuhgettaboutit"
Move the computer using a common and inexpensive kit. They're mounted too close to heat and they fail at 150k or so.
They aren't fast, but they're smooth and quiet (relatively speaking). Mostly bulletproof. I towed 10k with mine for years and never met a mountain it wouldn't top at 65mph with the A/C running.
You can get chips for them in nearly any configuration. You don't want to add fuel, but you can pick up power and MPG by scooting the timing forward just a hair. That will also clean up some black clouds. Mine regularly got 20mpg empty highway, 22mpg after the timing change. Towing 10k I got 14mpg regardless of timing.
I like them enough I'm considering one for a diesel swap in a 66 Bonneville, but a Duramax will likely win out if I can afford one.
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