Has anyone had good luck with a 6.5L turbo diesel?

[DetroitIron]

Hi guys, I mostly hang in the 73-87 forum..I recently picked up a truck camper too heavy for my old K20. Found an original owner 94 c3500 dually that appears to be well maintained and runs well with 134k on the odometer. Doing a lot of research has scared me on the 6.5 turbo diesel. I know it's not a powerhouse and that is ok as I just want something to take the truck camper out on the weekends. Should I avoid? Appreciate any advice.
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[DetroitIron]

Correction 1993 is the year
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[DZL1]

I have a 93 with a 6.5 turbo diesel. 105,000 miles but im not the original owner and I cant verify if those are original miles. What I do know is that ive owned the truck for almost two years and havent had any major engine trouble. What ive had to replace was the harmonic balancer, and an oil leak at the oil cooler.

Thats engine wise.

Other stuff I've had to do are: had to do brake work, change u joints, they were bad, change front end parts, idler, pitman and tie rod ends. Bad as well. Next will be to fix steering slop.

I dont use the truck to pull anything, and its not my daily driver. Hope this helps.

DZL1.

[DetroitIron]

Thanks DZL1. Just heard of some issues with weak bottom end and injection pump issues. The guy calls it his baby and always taken care off. Heck the air conditioning still works Since it won't be a daily driver, I thought it might me worth taking a chance on and then learn when needed to keep the truck camper dream alive

Anyone else have other info to share?
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[ProStreet68SB]

Keep it stock and you shouldn't have many issues.

[jayman68]

I believe it was the 6.2 that had the lower end problems, but if you took care of them they lasted well. I have heard that the 6.5 is a better engine. Good luck.

[jerrymp]

Yes, I had good luck with a 6.5 TD. My mistake was selling it.
First, with 135K on the clock, you can conclude you have a good "bottom end" - - i.e., the crank won't break and the block does not have cracks. These things don't occur with age, either you get them early or you don't. And truly, these are not real common events with the 6.5. A 6.5 is easy and cheap to work on if you want a diesel. Check you tube for how to do a blowby test. That will tell you the health of the engine. Drive it and punch it, a little black smoke is ok, but a lot is not. Mine was a 1/2 ton 4x4 with tall tires and was pretty anemic in that config. But a one ton dually will likely be 4:10 rearend and is a good combo for the 6.5. Beware, being a diesel head gets in the blood. You find you want to do stuff to it. I have had a 6.9, a 7.3, a 6.0 and an early 12v. Of them all, I liked working on the 6.5 TD the best. But a 6.5 TD will never eclipse any of those others with perhaps the exception of the 6.9. Lots of websites and forums to deal with 6.5 stuff. The most interesting is heathdiesel. That guy got 500HP and went 153 MPH in a 95 SBEC with a 4L80E.

[DetroitIron]

Thanks all...I may just take a chance on that old 1 ton :-)

[DetroitIron]

Originally Posted by jerrymp

Yes, I had good luck with a 6.5 TD. My mistake was selling it.
First, with 135K on the clock, you can conclude you have a good "bottom end" - - i.e., the crank won't break and the block does not have cracks. These things don't occur with age, either you get them early or you don't. And truly, these are not real common events with the 6.5. A 6.5 is easy and cheap to work on if you want a diesel. Check you tube for how to do a blowby test. That will tell you the health of the engine. Drive it and punch it, a little black smoke is ok, but a lot is not. Mine was a 1/2 ton 4x4 with tall tires and was pretty anemic in that config. But a one ton dually will likely be 4:10 rearend and is a good combo for the 6.5. Beware, being a diesel head gets in the blood. You find you want to do stuff to it. I have had a 6.9, a 7.3, a 6.0 and an early 12v. Of them all, I liked working on the 6.5 TD the best. But a 6.5 TD will never eclipse any of those others with perhaps the exception of the 6.9. Lots of websites and forums to deal with 6.5 stuff. The most interesting is heathdiesel. That guy got 500HP and went 153 MPH in a 95 SBEC with a 4L80E.

thanks! I checked out heathdiesel!

[special-K]

The only difference between 6.2s and 6.5s is the cylinder bore. The last 6.2 blocks are the same casting as the early 6.5s. The 92/93 6.5TDs use the same injector pump as the 6.2s,the DB2,and it's an excellent trouble-free pump. In '94 GM went EFI and started using the DS4 pump that had more issues,but most issues were actually the driver components mis-diagnosed as bad pumps because that was the symptom. My company truck is the '92 K3500 SRW that I ordered from GMC.It is just shy of 300,000 miles and has been a great truck. I did absolutely nothing under the hood,other than filter changes,till a little past 200k. Then,it got new injectors,pump,and glow plugs. Just last year a head cracked and had to be replaced at about 285,000. I have never touched the steering or suspension,other than idler arm about every 80k and change shocks. Everything else is original up front. I've never had to replace any u-joints,either. The rear springs have sagged and I recently installed Air lift auxiliary springs rather than remove and arch. It's been a great truck and still is.
A lot of black smoke means you're not burning all the fuel the pump is delivering. These motors can't take being built for more power. Just drive them. I have all the power I need. The truck gets right along and pulls anything you can give it. My truck has 285/75s and generally weighs 8,000#.

[OrangeAnimal]

The only one I have any experience with is a later model and it had issues with leaking oil. I think one too many hands had fooled with it by the time I got to it. Lot's of mis diagnosed stuff on it.

If it has been taken care of correctly you should have a decent truck. Like others have said just drive them. I know for some of us (myself included) that may be easier said than done but leaving it in stock form is best. If you want big power from a diesel get a Cummins.

[special-K]

I had a Penninsular Marine 300hp crate engine. I put in a Diesel Depot cam,intercooler,fluid dampener,custom mandrel bent cold air intake,and other mods making 325+hp in a '95. This was 10 years ago when 300hp was the most any diesel had. It was a lot of fun kicking diesel but with the underdog,but sure didn't last. Broke the crank and busted up the block in less than 30k.

[Ackattack]

Yeah, keep it stock and they're good engines. If she blows its a good excuse to swap in a cummins

[Classic73Garage]

A good friend of mine has one with 380k, with minimal issues. So far, it's still original engine and pump. His dad owned it from about new, and its been used to tow a boat and small trailers from ga to fl.
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[DetroitIron]

So I pulled the trigger tonight. My first dually and diesel. Going to keep all stock. She's a little rusty, but everything works great and came with a nice 5th wheel hitch set up. Cool hearing the turbo wind up. I vacuumed for an hour and still have more dirt and stuff in the cab to get at Should be fun to tinker with.
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[DetroitIron]

Post a pic tomorrow
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[Russell]

My 95 Tahoe started off as a 6.5L diesel engine. I actually really liked it! Good power, amazing exhaust tone and the loud turbo whistling away. I pulled down some impressive mileage with it too, 18 mpg on a truck lifted 7" with 37s and 5.13 gears at highway speed.

As mentioned above you need to make sure you have a look at the harmonic balancer on the truck. They are the #1 cause of failed rotating assemblies. That said, I've never actually seen a crank failure or personally known someone it has happened to either so I don't believe it is overly common. All 6.2 and 6.5L engines except for the newest Optimizer engines have cracked main webbings. I've pulled dozens of these engines apart and I've never found one without cracks. I've also never seen or heard of (including online) one of these engines failing due to cracked webbings.

These engines were designed with one thought in mind - fuel economy. They are light duty engines, and are not designed for big power or hauling gigantic loads. They'll do both with modifications but as mentioned above the relability just isn't there. I'd put the acceleration similar to that of a stock Vortec 4.3L V6 but the torque shows when the truck does not slow down at all with a load behind it vs running empty.

My 6.5L was running just fine when I pulled it out to replace it with an LB7 Duramax, but I did the swap for a few reasons:

1. To brag that my 95 2 door Tahoe on 1 tons is powered by an LB7 Duramax / ZF6 combo (haha!)
2. Cold starting is much, much improved with the Duramax engines.
3. No requirement for fuel lubricity additives (the 6.5L comes from a time when diesel still had sulphur which added lots of lubricating properties to the fuel. The I/P lives a short life when run on ULSD without additives. I used to run the Stanadyne stuff)
4. Much more power & way more potentially available with a tune.

In short - Run it and love it! Keep an eye on the balancer, and add lubricity additive with every tank and you'll be given years of reliable service and fantastic fuel economy.

[TheBlueBomber]

I've been wanting a 6.5TD for a while now. If the PMD (Pump mounted Driver) is still located on the stock location I would go ahead and buy a relocator kit from ssdieselsupply or heath and mount it away from the engine to keep it cool. A lot of failure from the truck is due to the PMD, Injection pump, and harmonic balancer. Also its an IDI truck (Indirect injection) so you cant dump fuel like in a cummins or powerstroke and "roll coal" itll just increase EGTs and cause a lot of problems. If you compare the output of power to a 454 and dont try to work it like a 5.9l cummins youll be fine. My buddy in Canada has a 6.5 and drives it everyday in the snow, rain, mud, etc and doesnt have any problems. Have fun with that dually!!!!!!!!

You can go wrong with a square body and an OBS chevrolet. Or any chevrolet in that matter lol!

[DetroitIron]

Super appreciate all the insight and feedback. I'm getting the inside clean and removing what's left of running boards. Her is a pic

[DetroitIron]

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[TheBlueBomber]

Originally Posted by DetroitIron

Super appreciate all the insight and feedback. I'm getting the inside clean and removing what's left of running boards. Her is a pic

That is a beautiful truck!!! All you gotta do now is yank that bug shield off, compound it and your good to go!!!

[DetroitIron]

Originally Posted by TheBlueBomber

That is a beautiful truck!!! All you gotta do now is yank that bug shield off, compound it and your good to go!!!

Thanks. Funny as I was very close to talking the bug shield off tonight while washing it for the first time. It got a lot brighter just with a wash...extended cab corners are rusting. Oh well I like it
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