1997 6.5

Jnw1860 · February 23, 2017

Looking at a 1997 3500 crew cab dually with a 6.5 and auto tranny. Not sure on gears or miles. Im a chevy guy but know nothing on this motor. Any info will help. Mainly concerned on how much I can tow and how good or reliable this motor is.

barry G · February 23, 2017

similar history to ford and dodge at that year.. although dodge and the 12v was a monster.

the 6.5 keeps a lower hp value, but the torque is there to do what you want. Go by the book of your truck.

the nv4500 manual tranny is much stronger, the automatic will need attention in frequent intervals.

diyer2 · February 23, 2017

http://www.dieselplace.com/forum/63-gm-diesel-engines/21-6-5l-diesel-engine/151958-just-how-much-can-1996-gmc-k3500-crew-cab-tow.html

google

moondoggiemn · February 26, 2017

Good Day

The following is an EXTREMELY brief summary, but should help. I would strongly suggest you join The Diesel Page (www.thedieselpage.com). It's the 1st, & IMHO best, source of info on the 6.5 & its drivetrain. I've avoided a spinoff, The Diesel Place. Some otherwise very good people had a hissy-fit because they don't like to pay for anything & started the Place. So you might have to pay an annual fee to access some of the Page forums where the Place is free; the Page is worth it.

IMHO* I wouldn't buy this truck unless a compression check was done. All cylinders should be ~ 400 psi. If it's been overheated, you'll see reduced compression in cylinder #8, then #6. The engine's not long for this world if compression's down in these cylinders.

"...auto tranny." Unless someone installed something non-factory, it's a 4L80-E. From the factory they're pretty strong; I've gotten > 275K miles on two of these without opening them. (I sold / gave away the trucks, they didn't break.) Rebuilt by the right rebuilder, they're unbreakable.

"Not sure on gears..." Unless special-ordered (which almost none were), it has 4.10 gears (41/10). These gears are pretty nearly perfect for the 6.5, although I'd prefer 3.73s (41/11) because I don't pull heavy very much.

"Mainly concerned on how much I can tow..." As long as you don't pretend you have a Powerstroke or Cummins, you should be fine. I've got > 500,000 miles on various 6.2 & (mostly) 6.5s, with no catastrophic problems; I've been extremely happy.

The word on the street is that the 6.5 eats cranks. If you push the power much above stock with modifications, & ignore other things (below), this can be a problem; if not, no problem.

I'm pretty sure a 1997 6.5 will have the high-output water pump. You can verify this by checking to see that it has the double thermostat setup; it's on top of the engine, connected to the top radiator hose - pretty obvious there's two 'stats in there & not just one. Many of us have upgraded our older trucks. The previous water pump was 87 gpm; the pump used with the double-'stat pumps 130 gpm. It only moves a little more coolant through the radiator. It moves a LOT more coolant through the block. The 6.5 would micro-boil coolant starting around cylinder #8 & #6, causing localized overheating & ultimately cylinder failure. The 130 gpm water pump moves so much coolant through the block that this mostly doesn't happen anymore.

"...how good or reliable this motor is." Ah - now the story gets interesting.

1) Does it still have the stylish plastic cover on top of the engine? I know they used these until at least the 95 model year. If it's still there, take it off & throw it far away. It hold heat in the engine, a very bad idea.

2) If you pull a camper, trailer, etc in the summer, don't shut it off when fueling, & get the hood open. There are two reasons. Folks have measured scary high under-hood temps in these circumstances. Also, when pulling hard, your turbo will be very hot. If you shut off the engine, the oil will coke on the bearings & the bearings will eventually fail. I have an EGT gauge & NEVER shut off the engine until it's under 300°F, & I also use synthetic oil, which has a much greater ability to deal with high temps.

3) Buy a spare FSD/PMD & keep it in the glovebox. This is the fuel solenoid driver / pump-mounted driver. If your truck is still stock, it's about the size & shape of a deck of cards & is mounted on the drivers side of the injection pump. (My favorite source of such parts is Kennedy Diesel; SS Diesel Supply is also excellent.) The Diesel Page folks determined that the heating / cooling cycles of the engine cause these to fail. Both Kennedy & SS sell remote mounting kits. The concept is to mount them where they'll never get so hot. On my 1995 K2500, I mounted it behind the driver-side headlights; on my 1995 K2500 Suburban I mounted it on the passenger-side where the air comes into the air filter box; my buddy's 1998 K3500 crew cab has it mounted on the aluminum gravel guard under the front of the engine.

4) Check the harmonic balancer for cracks in the rubber, every time you change oil. If it fails, it is likely to break the crankshaft. When these fail on gas engines, it's not too big a deal; on the diesel, it can be catastrophic.

5) Keep the batteries & battery cables in perfect condition. A gas engine will start if it's turning at all; a diesel must spin a certain rpm or greater, or it will never start. When it spins in-between rpms, they eat starters. Since I started buying top-quality batteries & keeping everything in good shape, I've had no more starter issues.

6) If you pull much at all, get an EGT & (preferably) mount it pre-turbo. NEVER let EGTs get above 1100-1200°F pre-turbo.

I know I've missed some stuff. Please go to The Diesel Page & mine it. They started the Page when it became apparent there were problems with the 6.5TD. They ferreted the problems out & discovered that they really weren't that big a deal, as long as you knew what to look for.

Blessings!

* In My Humble Opinion

moondoggiemn · February 27, 2017

Good Day

"Mainly concerned on how much I can tow..." I forgot to answer your original question. IMHO a 350 will probably out-drag race it; it will, however, outpull a 350 by a significant margin.

It would be nice to find out if this was of any help.

Happy Trails...

moondoggiemn · February 27, 2017

One more thing: Make sure the bracket from the back of the starter to the engine block is still there & intact. The starter on the 6.2 / 6.5 bolts onto the block with two bolts, like most Chev gas engines. On the 6.2 / 6/5, there's a stamped steel bracket that goes from one of the starter through-bolts to the engine block. There have been folks that broke the engine block where one of the two bolts hold it to the block. It's fixable, but difficult. I'm pretty sure this would never happen if the bracket was in place. When my daughter bought her 1988 6.2, the bracket was missing; one of the trucks I bought, it had broken in 1/2 & the other 1/2 was missing; my buddy's 1998 K3500 6.5TD came with it missing. It's a little trouble to get it in place & bolted down, so folks (apparently) figure it isn't necessary. They couldn't be more wrong. The last one I bought cost $15; cheap insurance.