The bastard child of diesels...the 6.5..a few questions

[Kilborg]

Well considering i totalled my towrig recently im in the market for something else. I was considering picking up a 6.5 turbo chevy. I know some of the gremlins regarding this engine and have worked on a few but have little firsthand experience with them outside of customers telling me their experiences. I'v driven a few and really like how they run, but im trying to get more of an idea here.

That being said, those of you that have ran the 6.5, i am basically just interested in the track record of your engine. Im not looking for the dmax/ctd/psd fanboys to come in here and tell me to spend 20,000$ on a used rig. I know the 6.5 needs help to get even to the stock levels of the modern diesels, but again, im not getting this truck for a powerhouse. It will be a DD and tow my toys to the woods on the weekends. That being said, i was towing 10k +/- with a 350, so a 6.5 even in stock trim should be more then satisfactory power wise...Iv grown out of spinning the tires through 3rd gear too.

Also, what are you guys seeing for fuel economy? Again, not looking for huge numbers or anything but if i could see 18mpg in a 1 ton single wheel auto i would be happy.

Anything else you guys can add would be helpful. Thanks in advance.

[Murph]

The main weak spot is the PMD - an electronic module that is glued to the IP. It gets cooked by engine heat (it's in the valley between the heads and UNDER the intake) and causes all sorts of chaos. Get a new one from Heath (7 year warranty) and leave the stocker on the IP "just in case".

http://www.heathdiesel.com/P/HDP1280/

Mine is mounted to the front splash shield just below the license plate.

I have no ideas on mileage #s, as I run WVO and fill the truck manually with a 6 gallon jug.


Andy

[BurnedBronco]

do not have a good track record as far as the trucks i work on. have done far more complete engines/heads on 6.5"s than i do powerstrokes and cummins of the same era, and i usually only see 15% of the diesel pickups thay i work on have a 6.5L.
they have a much higher failure rate when used as a work truck, and worked hard with poor maintenece. lots of cracked heads, holed pistons, and detroyed bottom ends. lot of its due to overworkign them, not changing oil, not keeping the oil full, and a few of GM's high quality oil cooler lines have claimed a few 6.5"s at my shop.

[Kilborg]

Very true, i didnt really take that into account. Considering my smallblock held up well in the 97 i would imagine the 6.5 will too in that regard. It seems most of the guys that actually towed 20k and the like had motor problems more often then even say a 454, but the guys who run service trucks and other rigs which see only occasional towing seem to be doing better.

[Kilborg]

repost....sorry.

[6.2Blazer]

My cousin pulled a large gooseneck with a backhoe on it. He had a early-90's Chevy truck with a TBI 454 he used for several years, and then bought basically the same truck with the 6.5 TD when they first came out. He thought the 6.5 pulled better than the 454, and got twice the mileage.

[axle59]

The 6.5 turbo is what they're using in the uparmored hummers right now. The trucks with all the armor and extra crap they're carrying around weigh in at close to 20k. Add to that that some of them even tow shit. The only problems I ever saw engine wise were when they shut down the engines and they wouldn't start again because of vaporlock.


Axle

[72fj40]

Electronic injection has issues. Alot of people have converted their eletronic injection to mech b/c of the constant failures. The aftermarket FSD/PMDs' have cured alot of the problems. 94-to approx 99 blks are a weaker, they added piston oil spray nossils in the blks in 94 for cooling, which weakend the blks. The 94-to approx 96 were the worst. The later yrs were better. 92-93 were mechanically injected and had stronger blks(599 blk). AMgeneral & navistar started making the blks for the hummer somewhere around 1999-2000. These blks were casted w/better material and added strength..

Bumping you up the boost a little and adding a 3 1/2" exhaust with an aftermarket down pipe does wonders. Check out Heath diesel, he does a thing called a turbo master which is helpful but you will have to ask him how much boost can be added to an electronic inj. w/o it throwing codes.

I'm running a 93 C2500 which is mech inj'd, I cracked a piston at 124k. Engine got hot and #4 piston swelled and snagged the cyldr wall. I rebuilt w/alot of power and cooling mods, 45k ago w/no issues. The truck is very strong now and runs way cooler. High EGT'S and water temps are the main killer of the 6.5td.

My .02ct. Mech injection is prefered.

As mentioned b4 the oil cooler lines can come loose especially to the later models. I've never had an issue though.

[Aces'n'8s]

When I was in college, I used to work for a landscape company that ran two 3500 duallies with the 6.5L turbo. IMO, the 6.5 was a good motor...good meaning it moved the truck and whatever load was attached to it from A to B.

These trucks were severely abused by the rigors landscaping duty. The interesting fact was this, one truck experienced a lot of overheating issues that cooked the engine electronics an numerous occasions. This same truck's engine got so hot one day that it cracked a head. The coolant reservoir ballooned up nicely and looked like a fish aquarium with all the air bubbles percolating up.

The other truck never had any issues aside from a failed charging system.

[u2slow]

The typical cracking between the intake & exhaust valves into the cooling passage can be fixed by pressing in a sleeve.

[72fj40]

FYI. Forgot to mention my 93 is auto 2wd w/4.10 gears and gets approx 15-16 mpg empty, when loaded w/approx 8500lbs it drops to approx 14-14.5 mpg. I don't travel as much as I used to, so I will be changing to 3.73's.


Also, I believe Military Hummers are naturally asperated.

[KWTMECH]

A friend has a 93 6.5 (mechanical inj) in his 82 pickup. We pumped that thing up and never have had issues. Truck fires off the line like it has a built 454 in it. 3.42 gears, th400 with an overdrive.

Edit: One mod I did. In the rear of the cylinder heads, there is a block off plate. One side (drivers) has the glow plug controller in it. (Removed that, now has a push button). Got another plate with the hole in it, installed it on the other side also. Came out of those hole, with a reducer bushing to 1/4 pipe. Plumbed in a 3/8 hose 1/4 pipe nipple. Brought both hoses up to a T and then came off the T to a 5/8 nipple. This now feeds the heater core. This mod took a lot of heat off the back of the block and the 2 rear cylinders that don't get a lot of ciculation. The number one problem of the 6.5s and 6.2s for that matter is the premature wear of #8 cylinder.

[72fj40]

The best cooling mod for the 92-93 6.5 is adapting the 94 cooling componets. Remove old water pump(60GPM) to the 94 W/P(130GPM) You need the 94 dual tstat crossover pipe and alter the 94 t stat housing outlet and use the later model fan and clutch. It increases the water flow something like 40 or 50% IIRC.

[axle59]

Originally Posted by 72fj40

Also, I believe Military Hummers are naturally asperated.

The new uparmored versions have a turbo.



Axle

[jaluhn]

From what I've heard, the chevys up to the duramax are all somewhat problematic. Don't know about the 6.5's, but I've heard quite a few 6.2's breaking cranks. IMHO, they're good as light duty engines, but I'd be careful loading them. Personally, I'd get a psd or cummins in the same price range. If nothing else, the simple fact that there's more of them is a good point. Unless you're in love with chevy or something.
~John

[BigDan]

It seems like these 6.5L are rare for the simple fact that they require a ton of mods and matience just to run around every day.

Ive never seen so many problems and mods need to make an engine run like its soppose to.

I think you will be money ahead if you do like everyones does and discard the 6.5L and get a more relieable power plant....

I cant imagine you feeling all warm and fussy inside towing your toys up into the mountains with a engine as prolbemattic as the 6.5L.

But hey I'm just trying to look out for ya, and not here to beat on my chest.

[KacksterK5]

Had one at work, truck had 250k on it, engine had been rebuilt once, tranny 3 times, new fuel injection, it was a 93 c2500 ex cab longbed with 4.10s and a locker. Truck moved ok and pulled its ass off for an old work truck. Had a full 60 gal diesel tank in bed, full toolbox, 550 brick, 2 350lb drop inlet grates in the bed once with a 17 ft enclosed hooked up to it. Pavement saw in the trailer with 300 gal of water. Pulled 75 mph on flat ground no prob. still had enough ass to pass someone if I had to. No hills here. That truck was tough till some russian bitch in an 18 wheeler cut me off and I tboned her. IT was empty then. I might buy it from the insurance company fix it and use it as a shop truck. Thing was great.

[slowdodge]

btw the real bastard children of diesels list goes like this 5.7 6.2 6.5 and 6.6 pending adoption. depending on how much it costs for a used 6.5 why not do a cummins swap in your existing chev truck just a thought. 6.5 are a pretty decent engine it just needs to left alone perfomance wise except for gauges, also a clean maintained fuel system will pay dividends in the long run.

[72fj40]

Originally Posted by slowdodge

btw the real bastard children of diesels list goes like this 5.7 6.2 6.5 and 6.6 pending adoption. depending on how much it costs for a used 6.5 why not do a cummins swap in your existing chev truck just a thought. 6.5 are a pretty decent engine it just needs to left alone perfomance wise except for gauges, also a clean maintained fuel system will pay dividends in the long run.

Actually, when I was doing research for a rebuild, I found various 6.5 web sites that came to the conclusion that stk 6.5's were more apt to have mechanical failures. The majority of failures are heat related, from a cooling system that is too small, an electronic injection/air intake system that allows high EGT'S in certain situations and engine design,(indirect inj.and too high compression 22:1.). Mods do have to be done within certain limits and keep EGTs in check.

GM is not the only manufacter of bastard children when it comes to Lt/med duty diesels.

[300sniper]

i had a '99 gmc suburban with the 6.5td for a while. i loved that rig and wish i had better luck with it. i bought it with about 100k miles on it. it kept going through coolant. it was not leaking any where i could see and not making any white smoke. i brought it back to the dealer that i bought it from and they said the intake was loose and that is where the coolant was going. i picked it up and a day later the coolant was low again. i brought it back to them and this time they said the head or block was cracked. they didn't want to pay to fix this and bought the rig back from me.

one more problem i had with it was the morning after i got it, it would not start. it would crank just fine but would not fire. i called up the dealer and they sent out a tow to pick it up. they said it was the oem security module. they replaced this and it started fine after that.

[roundhouse]

Originally Posted by jaluhn

Personally, I'd get a psd or cummins in the same price range.
~John

Can you get a PSD or Cummins for less than $5,000 ?

please share the source.

the 6.5s are dirt cheap compared to the big brands.
sometimes they are cheaper than the same truck with a gasser.

[u2slow]

Smashed 6.5s are such a commonality now there's a shop in town that regularly welds the main webs back together. Oddly enough these candidates still run and drive onto the hoist.

I had a '93 6.5TD with 4L80E and BW t-case available last week for $2500CDN. I have too many irons in the fire already, but I thought it was a decent price.

1st-gen PSD trucks are cheap/powerful/durable. I got mine under $10k (CDN) two years ago. Gotta be getting closer to $5k by now.

[saprobe]

Originally Posted by roundhouse

Can you get a PSD or Cummins for less than $5,000 ?

please share the source.

the 6.5s are dirt cheap compared to the big brands.
sometimes they are cheaper than the same truck with a gasser.

shop around,you can find 12v cummins trucks that need some TLC for under $5000 easily if you keep your eyeballs peeled. heres an example of one on one of the local boards here: http://www.cincyoffroad.com/index.ph...opic&topic=428

i swapped a 6.2 in place of the worn out 305 in my project truck. i like the 6.2 alot for what it is.it was an easy bolt in swap and a good learning experience for me,being a diesel newbie. ive got a banks turbo to put on it,and will prolly run it that way for a couple years(or until i blow it up pulling the 32 foot GN were gonna build ) till ive got the rest of the truck fixed up the way i want it and then it will get a 1st gen cummins

[ScoutIITD]

Originally Posted by 72fj40

The best cooling mod for the 92-93 6.5 is adapting the 94 cooling componets. Remove old water pump(60GPM) to the 94 W/P(130GPM) You need the 94 dual tstat crossover pipe and alter the 94 t stat housing outlet and use the later model fan and clutch. It increases the water flow something like 40 or 50% IIRC.

U got it wrong the 97's and up have the graded cooling/water pump.

The 97 - 99 are the weak blocks, but I have +210K miles on mine and it has never had the engine worked on. I've a pump installed under warranty a few alternators, but other than that it's factory stuff in that engine.

Carey

[Aces'n'8s]

Originally Posted by slowdodge

btw the real bastard children of diesels list goes like this 5.7 6.2 6.5 and 6.6 pending adoption.

I vividly remember a friend of mines grandfather that had an old 80's model Chevy Caprice wagon with the 350 diesel. That damn thing took 10 miles to reach hwy speeds and even longer to crank up if the outside temp was below 60 degrees..

Man was it a turd.