Forums » Grassroots Motorsports » Tell me about Chevy 6.5 Diesels 1 2

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  June 9, 2010 12:20 p.m. bravenrace Dork

  1997model. 134k. It seems to be down on power, but I've never driven one before. But my stock 454 seems more torquey. It blows some black smoke under acceleration, and sound at ldle like it has a minor miss. Anything I should be concerned about? It's a great price and the rest of the truck is good.

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  June 9, 2010 1:44 p.m. Nashco SuperDork

  Could be a failed vacuum pump, failed lift pump, stuck wastegate, failed wastegate solenoid valve, failed vacuum line, etc. I suspect the lift pump on the tiny bit of info provided.

  If I were to get a 6.5 turbo again (I had a '94 Suburban 6.5 TD), I'd get one from the first two years ('91-92 IIRC). Those years had a 6.5 turbo with mechanical injection instead of electronically controlled injection; the electronics on the 6.5 turbo are the only finicky part of the engine IMO, while the mechanical pumps were pretty robust and more zombie proof.

  Bryce

  Portland, OR | '69 Bug | '05 Saabaru | '95 Impreza | '67 122S | '07 Sky Redline | $2009 AWD Fiero Hybrid | '72 N600

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  June 9, 2010 2:13 p.m. HiTempguy HalfDork

  Nashco wrote: If I were to get a 6.5 turbo again (I had a '94 Suburban 6.5 TD), I'd get one from the first two years ('91-92 IIRC). Those years had a 6.5 turbo with mechanical injection instead of electronically controlled injection; the electronics on the 6.5 turbo are the only finicky part of the engine IMO, while the mechanical pumps were pretty robust and more zombie proof. Bryce

  I thought that there was only one part that was really failure prone on the newer ones, and everybody and their mother offers better parts with relocation kits for the piece now? The 98 turbo diesel had 215hp and 410ftpnds. Compare that to a 5.7L vortec at 245hp and 335ftlbs. I just wish I could find one in good shape :(

  Rallying; It's like skydiving, except you have to dodge trees on your way down!

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  June 9, 2010 3:15 p.m. Nashco SuperDork

  You're thinking of the pump mounted driver; yes they are failure prone, yes they can be relocated. I had one fail on me right after I got my Suburban, relocated it to behind the front bumper on a huge heatsink. The injection pump itself can fail as well; I had an optic sensor fail in mine (pump had 110k on it) and it's not really a "serviceable" part because it's a highly sensitive timing device so it should be bench calibrated after replacement. New injection pumps are $$$$, I went with an ebay special reman from a rep with good feedback...by the THIRD pump install, I finally got one that worked out of the box. Not the engine's fault, and the previous one lasted a long time, just a crummy rebuilder that I was forced to use trying to avoid the hit of a new pump.

  When I bought my Suburban it had a failed lift pump and vacuum pump. Both were pretty cheap and easy fixes. The moral of the story is that my experience shows the fuel system is a bit finicky when they get high mileage...the rest of the powertrain is solid. So, IMO, it's best to get one that has ALL of the same solid powertrain and without the electronic injection. Well, that or pony up and get a Duramax.

  Bryce

  Portland, OR | '69 Bug | '05 Saabaru | '95 Impreza | '67 122S | '07 Sky Redline | $2009 AWD Fiero Hybrid | '72 N600

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  June 9, 2010 6:29 p.m. bravenrace Dork

  I used to be a diesel tech, but I've never heard of a lift pump. What is it? And is it unlikely that there's anything major wrong with the engine? How durable is the engine itself?

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  June 9, 2010 6:46 p.m. Streetwiseguy Reader

  What about the part where they split the blocks in the vee when they are turbocharged? Nobody had to spend that kinda dollars yet? Installed the girdle on the new block?

  Be afraid, be very afraid.

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  June 9, 2010 6:50 p.m. bravenrace Dork

  They're turbocharged from the factory. Are you talking about that or running more boost than stock?

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  June 9, 2010 7:11 p.m. CaptainSpaulding New Reader

  bravenrace wrote: I used to be a diesel tech, but I've never heard of a lift pump. What is it? And is it unlikely that there's anything major wrong with the engine? How durable is the engine itself?

  Lift pump is a fuel pump that feeds the injection pump.

  Pretty much all of the light duty trucks have one.

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  June 9, 2010 7:12 p.m. CaptainSpaulding New Reader

  Streetwiseguy wrote: What about the part where they split the blocks in the vee when they are turbocharged? Nobody had to spend that kinda dollars yet? Installed the girdle on the new block? Be afraid, be very afraid.

  huh......

  The 6.5s came with a turbo on them. Heck you can bolt a complete early 6.5 turbo onto a 6.2 with excellent results.

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  June 10, 2010 7:50 a.m. bravenrace Dork

  CaptainSpaulding wrote:

  bravenrace wrote: I used to be a diesel tech, but I've never heard of a lift pump. What is it? And is it unlikely that there's anything major wrong with the engine? How durable is the engine itself?

  Lift pump is a fuel pump that feeds the injection pump.

  Pretty much all of the light duty trucks have one.

  Ah. We called those supply pumps.

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  June 10, 2010 7:51 a.m. bravenrace Dork

  Streetwiseguy wrote: What about the part where they split the blocks in the vee when they are turbocharged? Nobody had to spend that kinda dollars yet? Installed the girdle on the new block? Be afraid, be very afraid.

  So can you explain further????

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  June 10, 2010 8:24 a.m. Streetwiseguy Reader

  bravenrace wrote:

  Streetwiseguy wrote: What about the part where they split the blocks in the vee when they are turbocharged? Nobody had to spend that kinda dollars yet? Installed the girdle on the new block? Be afraid, be very afraid.

  So can you explain further????

  Maybe, once again, it has to do with the cold weather we see up here, but just like noisy pistons in Neons, the 6.5 turbodiesels destroy themselves in short order. There are exactly NONE left around here.

  http://flashoffroad.com/Diesel/No8Cyl/CrackedBlock.htm

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  June 10, 2010 10:02 a.m. HiTempguy HalfDork

  Streetwiseguy wrote: Maybe, once again, it has to do with the cold weather we see up here, but just like noisy pistons in Neons, the 6.5 turbodiesels destroy themselves in short order. There are exactly NONE left around here. http://flashoffroad.com/Diesel/No8Cyl/CrackedBlock.htm

  Just because every redneck in Alberta bought one and never bothered to warm them up properly does not mean they were a bad motor.

  Rallying; It's like skydiving, except you have to dodge trees on your way down!

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  June 10, 2010 10:08 a.m. CaptainSpaulding New Reader

  Weird. I have been around those trucks and motors for years and never seen one crack like that let one al of them i a certain region.

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  June 10, 2010 5:50 p.m. bravenrace Dork

  Okay, so I need some help making this decision. The truck is a loaded '97 k3500 extended cab dually. It's rust free, and drives nice, except for the aforementioned engine issues. They're asking $6900 for it and I'd expect to pay $6000 for it. It sounds to me like the engine issue is likely minor, correct me if I'm wrong. It may not even be low on power after seeing the specs. I expected it to have more torque than my current truck, a '78 C-30 with a mildly built 454. But I figure that engine makes about 280hp and 450ft lbs of torque, so maybe I'm expecting too much from the 6.5. I've just never driven one before to compare it to. So what do you guys think?

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  June 10, 2010 6:14 p.m. Gearheadotaku Dork

  I think the 6.5 will do a good job once dialed in and will save you a ton on fuel over the 454.

  Old enough to know better, too young too care!

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  June 11, 2010 1:10 p.m. Hopsonn New Reader

  In reply to bravenrace:

  The truck is likely fairly decent, but I would say be prepared to do alot of maintenance work. My dad used one for 250,000 miles with what you could call acceptable reliability once a few major issues were resolved. His truck was 4wd and seemed to eat front ends. A cold weather fueling issue left him stranded several times. He didn't get very impressive gas mileage under any circumstances (low teens) and the truck was incredibly heavy and slow, though didn't feel much more strained when towing than when just pushing itself. Torque really isn't too impressive compared to modern diesels either I believe his 95' was rated 180hp/360tq.

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  June 11, 2010 3:23 p.m. ClemSparks SuperDork

  The 6.2 and 6.5 guys compare the output of the NA diesels (admittedly NOT what you're asking about here) to 305 gassers. The turbo adds a little...but If you think the power output seems down compared to a big block...it's very possible everything is fine.

  However, it's also very possible that something (like...say...an injection pump) is on its way out.
  

  The injection pumps on these things pretty much turned me off GM diesels (I had an '83 and it just never ran...).

  Is that really the going rate for those trucks? Seems expensive, but I've not been in the market (so it's probably about right).

  Clem

  Yeah, well...sometimes even when it IS broken I don't fix it.

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  June 11, 2010 5:12 p.m. CaptainSpaulding New Reader

  My 84 6.2 chevy was SLOW and dead nuts reliable.

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  June 12, 2010 1:21 a.m. Nashco SuperDork

  I had a 6.2 NA Suburban, it couldn't get out of it's own way, but it was pretty damn reliable and easier to work on. The 6.5 TD wasn't a speed demon, but it got the job done. The 6.2 got high teens consistently, 20 mpg max. The 6.5 got mid teens consistently, 19 max. The 6.2 Suburban was a $500 purchase and took another few hundred bucks to get it in good running condition. The 6.5 Suburban was a $2000 purchase and took another few hundred bucks to get in good running condition. IMO, these were great deals and that's why I picked them up, they usually go for about double those prices. I converted both to burn waste veggie oil, the earlier one took to it much better because of the less finicky fuel system. That was about the ONLY part of the older Suburban that was better...the newer one was better in pretty much every other regard. Oh, and to be clear, the fuel system problems I had with the 6.5 were before the veggie oil conversion.

  IMO, for a '97 it'd have to be in GREAT shape to be worth $6k. With only 130k miles, it might be. At that price point, you're not far off from a newer truck with a Duramax, which is going to be light years better.

  Bryce

  Portland, OR | '69 Bug | '05 Saabaru | '95 Impreza | '67 122S | '07 Sky Redline | $2009 AWD Fiero Hybrid | '72 N600

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  June 12, 2010 11:50 a.m. 93gsxturbo Reader

  $6k is reasonable for a diesel dually 4x4 with a good running 6.5.

  These trucks do seem to have a bit of a lope to them at idle. If there is not much blowby coming from the oil fill tube once its warmed up, you are good to go.
  

  Plan on putting in new injectors when you get it unless its been verified that they were replaced recently. Its an every 100k mile thing on those trucks. Makes them start and run a ton better. Bump the timing up with either a Snap-On MT-2500 or a Tech II and you will be really happy with how they run.
  

  They are great motors as long as you don't expect them to pull like a Cummins. Parts and service are cheapest and easiest of any of the diesel motors from the Big 3.

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  June 12, 2010 11:59 a.m. CaptainSpaulding New Reader

  I have found that the 6.2/6.5 parts prices are roughly the same as the 6.9/7.3 IDI Fords.

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  June 14, 2010 7:36 a.m. bravenrace Dork

  Thanks for the information. I wonder if some of you guys have been in the used truck market lately. $6900 For this truck in this area is a terrific price. It should be over $10k, which is why I'm suspicious of the engine. Trucks are outrageously high priced around here. I've looked at $15k trucks with 150k on them and rusted out rocker panels. This particular truck looks better than new, with a high end paint job, no rust, new tires, etc.. It needs nothing except a seat cover to hide the cracked leather seat, and whatever the engine might need. Duramax? I haven't found one under $20k.
  One question - If all these old diesels get is mid-high teens for mileage, why bother? My BIL's '01 Silverado 1/2 ton gets high teens with a 5.3 and has more power than this 6.5 had. I guess if we are talking 1 ton dually's only, then it makes more sense, as I think the only engines available in '97 were the 5.7 (low on power), 454 (gas hog), and the 6.5. At this point, I'm really leaning towards just keeping my old truck, as I think the used truck prices are way too high right now. Keep in mind that I live in the rust belt, and trucks here start rusting within 5 years if they aren't taken care of well. I looked at an '02 dodge and '01 F-150 the other day, and they both had rusted out cab mounts. They wanted $11k for the dodge and $9k for the F-150. It's unreal. I can waste a lot of gas in my 454 before making up for that.

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  June 14, 2010 11:48 a.m. Nashco SuperDork

  bravenrace wrote: Trucks are outrageously high priced around here.

  So, have you considered looking somewhere else? There's a hell of a lot of rust free, good condition trucks down south calling your name. Texas is a big, dry, truck-lovin' state...lots of trucks on the used market.

  One question - If all these old diesels get is mid-high teens for mileage, why bother?

  You asked us about the 6.5 diesel, not the best truck for your buck. Personally, I got a diesel because I was burning veggie oil in them...it's REALLY hard to burn veggie oil in a gas engine. Also, keep in mind what the fuel economy numbers are pulling a load and empty and factor for that based on how you're going to use the vehicle and for what distances. While the 6.5TD Suburban got a max of 20 mpg, the worst I ever got was about 12.5 mpg pulling a loaded truck and trailer over mountain passes. If you haul heavy loads for long distances, the diesel quickly becomes more attractive than gas on a cost basis.

  Bryce

  Portland, OR | '69 Bug | '05 Saabaru | '95 Impreza | '67 122S | '07 Sky Redline | $2009 AWD Fiero Hybrid | '72 N600

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  June 14, 2010 12:31 p.m. 93gsxturbo Reader

  Early Dodge trucks with the VE or P7100 mechanical pumps will return low to mid 20s for empty or lightly loaded cruising. They are your mileage kings for sure.

  My friend sees nearly 20 MPG from his 6.5/5 Speed K3500 Short cab long box SRW. Timing is bumped and injectors have high pop pressure.

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