Is the 6.5l a good engine?
 

I am looking at GMC truck with the 6.5 L engine. *What should I look for or ask about the engine? *The injectors and the injector pump have been replaced recently and he has the receipts for that. *It has the FSD cooler. The truck has 130000 miles. This would be my first diesel truck, how does this engine usually start in the wintertime? I live in Kansas.

Thanks guys!

I would take it to a mechanic and have a leakdown test done on it. Yes it will cost you some $$ but may save you $$$$$$ in the long run.

My story- I purchased a 93 6.5LTD July of last year, 145K miles. After I drove it for a couple of weeks I found out it was loosing coolant somewhere. (I drive it only in the evenings and weekends due to a work vehicle). After a couple more months of a couple miles here and a few more here I found out I had a cracked head.:scare2: Somewhat common for this engine. Talked to a mech about pulling the head and replacing it, and when I was told 3500.00 I decided to replace the engine with a new one(New not rebuilt) along with the mechanical fuel pump, injectors, glow plugs(93 is a mechanical-94 up are electronic injection). 8K later, my new engine is in and running with me installing the engine.:jump:

I love my truck, but again, if I had it to do over again, I would have spent the money to check it out by a professional familiar with Diesels.....

If you decide to have it checked out go to Standyne's website and find a mech in your area that is certified to work on them......:s:

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Yes they are good engines. They are used overseas for generators and pretty popular from what I was told for that use.

I do have a great connection for an engine if you need one. Their customer service is top notch and they specialize in the 6.5L exclusively

Is the 6.5 a "good" engine?

Simple answer: no.

It is an affordable rig for that was built for mileage but it is not considered overbuilt or durable.

Issues:

Lift pumps die regularly. result - rough running/power loss/ip strain
IP dies. result - no start/doesn't run right
oil pressure switch burns out. result - no start
Harmonic balance deteriorates. result - broken crank
Crank pulley deteriorates. result - broken crank
Weak block casting. result - cracked main webs/cracked head bolt holes/cracked cylinder bores/broken starter mounts
Heat issues in the heads. result - cracked valve bridges/water in combustion chamber
Poor head gasket clamping. result - blown head gaskets
Injectors - only good for around 100,000 before replacement. Result - everything from rough running to a holed piston.
Failing vacuum turbo control system. result- low power, rolling black smoke, overheating, burnt up engine.
Electronics - PMD overheat issues. Result - all kinds of whacky troubles from no start to engine run aways.....:scare2:

Then there's just the simple fact that even the "newest" one is old. Mileage, rust, etc all take their toll over the years.

The 6.5 is good for about 300,000 miles and then it's looking for a rebuild/replace. It can go longer, but very few break 400,000. And that's if they've been lightly used and taken care of. There's always going to be someone spark up "I've towed 20,000 CGVWR every day for the last 20 years and haven't done a thing to it, i got well over 400,000 on mine" to that last comment, but they're very rare if true and even then they've been very lucky....take those claims with a grain of salt

Plus all the other common problems in an older GMT400 chassis (ie: front end components, ignition switches, windshield leaks, rotted cab corners, etc)

Now, the good stuff;

Because of these problems (which your truck may or may not have) they are perceived as "turds". This means they are an affordable diesel to purchase.

They are still also relatively "simple" diesels so you don't need a PHD in electro-mechanical engineering to work on them.

Emissionsare nearly non existent.

Fuel MPG is good for such and old hack. 13-15 mpg combined is normal, some can get slightly over 20 mpg highway running (depending on condition, speed, gearing, etc).

Parts are relatively cheap compared to modern diesels.

As long as the block is still sound (IE: not cracked and there's no way to know other than tear it down so you're taking a chance) most issues are also affordable fixes.

For example:

500 bucks relocated your PMD outside the engine bay and you can get 10 odd years out of it. A full set of injectors only costs around 400-500 bucks (price out a duramax and you'll see why thats good!). The OPS can be fixed with a bit of wiring and a relay. Glow plugs can be had for around 8-10 bucks a piece (good duraterms, not cheap ones).

A 6.5 can be a good truck, if you do some work and accept it's limitations. It's a light duty diesel made for MPG. You can work it (towing) but it's not intended for full time commercial use. It will do it, but you're taking life off it every time.

It's never going to make much more than 250-300 hp. It's going to take mucho buckos to cross 500 lb/ft.

If you're looking for a truck you can pick up cheap, put a little money in ot, drive it lightly or tow a bit, it can be a good choice.

Just make sure you get one in decent shape to start with.

Things to look for:

Hows it start? smokey? smoke color? Blue=bad, Whitish grey = unburnt fuel (can be ok if it clears in short order), white = coolant in combustion chamber.

Does it roll black smoke on acceleration? if so, the Vacuum system for the turbo wastegate is toast. A properly running 6.5 has almost no black smoke. Good news it's usually and easy fix. 50 bucks for the solenoid valve, 150 bucks for a vacuum pump, 100 bucks for a vacuum actuator or simple vacuum line replacement.

Pull the intake boot off the turbo. Check for play in the wheel (with the engine off!!!). Side to side movement is acceptable as long as the wheel doesn't touch the housing. It floats on oil on plain bearing so no oil pressure side to side movement is normal (but no touchy the side walls!). If the wheel moves in and out a lot that's a different story, the turbo is getting ready for replacement. looking at around 800-1200 for a replacement GM turbo. Around 800 for an aftermarket "upgrade". When something spins 150,000 odd rpm, it deteriorates fast once it starts to go. Worst case scenario; the wheel comes apart and sprays metal into the engine....

Pull the filler cap. Does it chuff smoke? Can indicate worn rings or cylinder bores. Some will say it's a bad CDR, but if it's a higher milage engien 99% of the time is cylinder/ring wear. If it's puffing smoke from the dipstick tube and the dipstick is still in, turn around and walk away. It's ready to die on you.

If it's got a small amount of smoke from the filler, it's probably OK. Take it for a test drive with a friend and pull over in a parking lot. Take a long piece of clear tubing with you that fits over the dipstick tube and a bottel of water. Slip the tube over the dip stick tube and the other end in the water. Hold the bottle down by the tire and get your buddy to rev the engine to about 2000rpm. If the water rises a couple inches, the engine is in decent health, if it rises 4-6 (or more inches) it's probably got a bad CDR valve, if it pushes the water down a couple inches or it blows bubbles in the water, drive back to the owner and hand him back the keys. It's about to die.

Also look veeery closely at the starter mounting area. These blocks have been known to crack off in this area and owners "buck shee" the starter back on to sell them. This is always a temporary fix and once it lets go again the only fix is to replace the entire block!

:scare2:

Good luck, take your time and check it over thoroughly.

There over in the $10,000 to $20,000 more section.

To say it isn't a good engine is a bit of a stretch. There is better stuff out there but better stuff comes with a price. Both in initial cost and maintenance when things break. (6.5 injectors $300-$600 Duramax injectors $2000-$4000) Most of the problems that a 6.5 have can be avoided by fixing small things when they break and not over heating them. Most crank shaft failures are caused by bad front pulleys or flywheels. Head gaskets let go when you over heat them.

I have owned quite a few of them and have never regretted buying any of them. Every one of them has given me years of good use at least into the 300k mark and most of the time when you get there you don't have much truck left anyway. I drive mine to work every day at my machine shop, if I need to make deliveries I throw the stuff on the back and make them, if I need to pull a trailer I do whether it weighs 2,000lbs or 15,000lbs.

A 6.5 is what it is. A early 1980's diesel(6.2) and one of the first diesels put in a light duty pickup. If you want to make big power or pull a gigantic trailer everywhere don't buy one. If you just want a truck to drive around and pull a trailer every now and then there fine.

Nah, not at all.

As delivered, they have a lot of problems.

Some can be fixed, some cannot.

For example:

fixable/preventable - OPS problems

Not fixable/not preventable - cracking cylinder bores/main webs/heads

Fixable but always a pain waiting to bite you in the @$$ - PMD

Don't get me wrong, I've got a 6.5.

I like the old truck.

It gets the job done that I need. It starts reliably every day in all weather. Hot, cold, or whatever. It takes me back and forth to work every day.

But, I had to spend waaayyy too much to get it to this point; IE: Optimizer, injectors, glow plugs, replace turbo, PMD relocation, fluidampr, water injection, turbo master, 4" exhaust, etc, etc, etc....and it's still just barely adequate at best to pull our 7500-ish lb travel trailer on weekend outings.

If I had it all to do over again I would have just walked on past the 6.5.

So to examine whether or not the engine is good; No, it's not a good engine.

No matter what you do, you can't spend enough to "fix" a cracked block/cylinder/head and there's no way of preventing those issues. Finding a rebuildable block and/or heads is nearly impossible. Replacement is the only lasting cure. It's a bad engine design right out of the gate and that's why AMG/GEP changed/redesigned it a couple times in pursuit of something that works reliably without all the associated "hard part" failures.

If I had known then what I now; I would have bit the bullet, spent more money up front and simply bought a better rig to begin with.

The GM 6.5 engine is a bad design, no matter how you slice it. Truth is something we don't want to admit sometimes. I didn't and just kept pouring money down the hole until it bottomed out...

However, the GMT400/4L80E/corporate 14 bolt that's attached to it is one good old truck, even with it's few "character flaws"......:w2:

keep it stock and you'll be ok maintain it religiously, do all the the things you have to do

bless his heart, crazy had a 6.5 that put out 4x the power of a powerstroke

my bosses 6.5 has 467,000mi and still running

everyone has their own opinion

Umm, don't you think you're exaggerating just a "wee bit"?






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lol swear he told me that its in an older thread i will find it for you tho

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[QUOTE=cjmdjm;863465]yup blow up in Ga. had to buy other truck fast so ca get back to Fl. so i ended up with 94 F-350 turbo IDI it great running and looking truck but don,t if going to hang onto it or sell for other 97+ 6.5 the 6.5 after all work have done to it has 4 time power of 7.3
QUOTE]

Not to speak ill of a guy once he's gone but:

1st year powerstroke was lowest hp powerstroke - about 185 hp.

4x that is 740 hp.

So, how big was that fish again?

;)


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obviously he was exaggerating i was just quoting a line :moon:

Not to be a PITA, but that's how all this inaccurate info gets out on the net and how young 'uns get thinking they can pull 400-500 hp out of a 6.5 with an air filter, an exhaust and a "tune"......:moon:

You're looking at 250 hp if you put a lot of work into it. 300 hp is a difficult mark to hit even with a lot of cash. 400 is right out there and you're getting into a truck that can't be daily driven. 500 hp is a rare group of 1-2 trucks worldwide. More than 500 are unrealistic claims and "pie in the sky "and not much more. There's only 1 truck in that range that I would half believe is true....



(next part not directed at anyone specific)




The TD 6.5 is a poor design right out of the gate. GM rushed stanadyne into the electronic diesel injection market prior to when stanadyne felt they were ready. GM felt the need to compete (ie: "out do") with the Dodge/Cummins and Ford/International and wanted to be first to market in a couple areas. Chuck a turbo and half breed electronic injection on a 10-ish year old IDI and see what happens.

Looky looky! We gots electronic diesel injection first! We the best! Heartbeat! Like a Rock! Buy our stuff!

Surprise surprise; rampant failures of all types and description followed.

Shot themselves right in the foot.

Then came the endless recalls, "secret" factory replacement policies and finally a "very quietly announced" extended warranty program. Didn't matter, damage done, reputation ruined.

PMD issues, all kinds of electronic failures, failing rotary pumps, wastegate issues (mostly due to the poor solenoid design), cracking main webs, core shifted blocks, severe overheating, tooling clipped cylinder walls, etc, etc, etc.......bad ideas and poorly executed. Maintenance, even religious maintenance, can't mitigate those issues.

That's not just my "opinion", it's been proven out over and over. Don't believe it? Google......

It's not a matter of IF a 6.5 will fail but WHEN. Age and mileage only make it more likely.

High mileage is not an indicator of reliability either.

My truck has 425,000 on it.

But it's had 3 engines (including original), a couple PMD's, two IP, etc, etc, etc.....

Bad design from the get go. That's why GM abandoned the design. Unreliable and incapable of keeping up with the other OE's. And it's not like GM didn't throw a fair bit of engineering at it trying to fix the issues either. Just look at the cooling gymnastics they went through to get it to the point where it was merely "acceptable" in 2000 to keep up with the overheating issues....couple different pump revisions, bypass, crossovers, single or dual starts, several different clutch fans and at least 3 fans redesigns. That dog never did hunt......

Now that I've got an optimizer in there, I'm hoping the block and head problems are at least handled. A Heath PMD will hopefully take care of the PMD issues, although I've always got a spare in the glove box. Spare IP sitting on the shelf in the garage.

I like my truck, but I don't turn my back on it, not even for a second.....I know what it is, and won't ever forget it; a problem waiting to happen and stick it's fingers deep into my wallet again and again.

If the OP intendeds to get a 6.5 truck, you have to be mechanically inclined and able to accept "down time".

Not only because it IS going to break, but because no one knows how to work on these forgotten "half breed" diesels. It's not just that they don't remember, they never really knew...

The price of admission with a GM 6.5 is low because of it's poor reputation (and it earned that rep). They are a good buy in that respect.

However, you pay out on the back end in both time an labor.

Don't get me wrong, I like my old truck but here's the advice I'd offer anyone considering a 6.5:

If it's in decent shape and running; buy it, drive it while it runs, don't expect a lot out of it and get rid of it when it starts costing you 500 bucks at a sitting....

I have to agree with No it's not a good engine. :nope:

Yup, been floating around for a while. Last I heard it blew up on him....


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Coming from a family of truck and tractor pullers you learn that's what they do. You pull for awhile then they blow up, you rebuild them and start the circle over.

A 6.2/6.5 is what it is. There's better stuff out now but when it was first designed there was no diesel in light duty truck's to look to for what worked good and what didn't. What it was built to do in the early 80's was mpg's and it did that very well. The major problems with them are exaggerated to huge proportions. Cracked heads are a surface crack. The deck of the head between the valves is too far from the coolant passage. The surface gets hot and cracks till it gets to cool metal and stops. If your that worried about the cracks don't weld them brass pin them. Busted mains can happen to any of them but 96 1/2 and newer are more prone to it. Main studs also reduces the chance of it happening. Out of the 5 6.5 I have ever owned I have never had a main break and only seen one break in a 97. Cranks can break but the chance can also be reduced by not running one with a bad damper and even more if you go to a fluid damper. Never had one break a crank.

I can only speak from my experience with the 6.5 and every one I have ever owned gave me years of good service and I have never regretted buy any of them.

I'll post one last thing and I'm done. Read:

http://www.enginebuildermag.com/Arti...izer_6500.aspx

The OEM gm 6.5 was a poor design right from the get go and to compound matters the manufacturing was poorly executed.

Good idea (mpg meister), poor design (crack master)....


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1995 Gmc 2500 TD
 

I have a 1995 Gmc 2500 Turbo Diesel with 304,000 miles on it and :jump:no problems

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I owned a 6.5 for about a year it has 304,000 miles on it. i had no problems since i owned it. its a very reliable engine. but it does not compete with the newer diesels tho.:rocking:

Obviously you have had bad luck with yours. GM abandoned the design because it was old technology. So is that the same reason Ford abandoned the 7.3L? Because it was a pile of crap too? Don't think so. There comes a time when they no longer meetb emissions, or they came up with a new design with better power.

And I hate to tell you, but every mechanical thing on earth will fail at some point. If engines never failed they wouldn't sell replacements.

And on the $500 get rid of it. That's up to you. I have 3 friends with powerstrokes, and all of them have spent more money keeping that truck on the road before 170,000, than I have on my 6.5L. Not saying that stuff can't happen to a 6.5L. I have had great luck with mine. But there are other things that can fail and cost you money.

I own 3 6.5L diesels currently and have been problem free up until recently with an IP that went out of my 96 crew cab. Unfortunately i attribute some of that to my own fault. Here in illinois, we get our share of salt and rust potential. This truck was an old state truck and my LP had a pin hole which sucked air and then burned the IP up. My 98 suburban is converted to veggie and my 99 suburban was babied by the previous owner and is running great. I like the 6.5L TD but opinions and experiences abound for others.
thanks

I bought a 6.5 last year or had 200k miles I replaced the injectors and relocated the pmd it now has over 400k miles and still runs as strong as when I bought it.

I'm looking at buying a 1992 chevy 6.5l turbo with 194000 miles what should I look for when I'm looking at it?

As far as the engine you might ask about the turbo, injectors, injection pump, glow plugs, harmonic balancer, and starter.

Make sure its cold when you start it, like sat over night atleast, glow plugs light should come on for 5-8sec. Crank it up with the hood open and check the upper Radiator hose, if you can't squeeze your fingers together and pinch it then it has a bad head or head gasket. Also check for a smoke cloud when you fire it up and make sure it doesn't puff smoke out the exhaust from a low hole (can also check that through the oil fill as blow by)

If it passes that then take it for a 15-20 min drive to get up to temp, should get up to 190 (if not then T stat is stuck), pull the oil fill cap and check for blow by (you dont want it to look like a freight train).

Check for leaks and general nit picking over condition next.

All of you um.. fine people.. crying about cracked mains and headgasket problems know the block was redesigned midway through production that took care of those issues right? Headgaskets only go when you overheat them, its the owners responsibility to keep an eye on the temp gauge. Any engine can be shelled with abuse, any. Injector life of 100k is not a design flaw that was intended and are supposed to be changed every 100k as MAINTENANCE not when they fail after 190k miles. 6.5s are a great engine if you take care of them and they shared a injection pump with 7.3L powered fords, you dont hear cries of junk pumps from that crowd do you? 6.5's being a bad engine is a bandwagon topic, everyone knows someone that grenaded one or dumped way to much money into one to fix simple issues not knowing any better. :humm:

Comparing a mid 90's indirect injected diesel to a 00's direct injected diesel is apples to oranges and a waste of bandwith. No idi diesel will ever compete with a new di diesel power wise. just not possiable. Want a good cheap workhorse? buy a idi diesel. want to race your honda buddies on the weekends to? buy a di diesel and get your checkbook ready.

humvee's run 6.5's, isnt it funny that an engine good enough for our military to send troops into battle everyday isnt good enough for forum warriors?

I love mine Just took a 700 mile round trip and got 21.26 MPG, and I have gas burner that don't get half that.

Erm..... they are good enough, if the price is good enough..

A 2wd manual can get good milage.... apparently a 4x4 auto cannot, because our regular cab gets 13 mpg. As far as reliability, ours is low milage (145k) but other than the PMD we haven't had any issues at all. You hear all of the horror stories, but short of catastrophic failures these motors are one of the most dependable daily drivers there is. They also start excellently in cold weather. They won't win many (or any) races, but they will pull anything you put behind them. We grenaded the rearend in a straight truck a couple of years ago, and (with the rearend completely locked up) pulled it 3 miles with our 6.5. The truck weighs in at about 43 thousand pounds, so that was no small feat.

TL;DR Good all around engines that don't really excel in any one area. Low milage and maintenance are EVERYTHING.

They change the 6.5 block many times over the years but never fixed it until navistar bought the rights in 01 and gm stopped using the 6.5.

IMO anything over 200k miles on the stock head bolts is asking for a head gasket problem but that said I've ran 2 over 300k with no issues and blew a gasket on a 3rd at 230k.

Injector rebuilds are cheap, change the glow plugs with ac delco 60g's or Bosch duratherms while you're in there.

94 and newer needs the pmd relocated.

My 95 k1500 z71 regularly got 19mpg and better on highway with 3.73 gears. My 94 K3500 single cab srw got 16 easily before I swapped the turbo and 18 highway after with 4.10's. My 93 K3500 service truck weighing in at 12.5k gets 13-14mpg highway. Trick is finding your trucks sweet spot to cruise in, might not be 75mph.

Looking at a 99' GMC 3500HD dump with 56,000 :humm: miles on it. Going to use your recommendations on what to look for before even thinking about this one..... I do like the "affordable" repair levels on this engine though. Any suggestions on what to look for on a low mileage vehicle like this?

By definition a good engine is one I would gladly install in a one engine air plane.

I would NEVER get in a plane that was powered by a 6.5L Turbo Diesel. NEVER

your definition maybe, but i would argue that our military rides to war on the backs of 6.5s every day and so does a large chunk of our fishing fleet. it is a very popular maritime engine and those people dont take dependability lightly. What idiot would think about putting a low rpm large block diesel in a plane? Kind of like saying i wouldnt run a 6.5 cause it wouldnt be good in a f1 car. :td:

Whoa with name calling their bub. It was a loose analogy, equating the well-known reliability issues of the 6.5 to a situation where all one really needs is reliability.

Stinks in here, to many folks

https://smalbanynewyork.files.wordpr...-ass.jpg?w=200

To bad the "well known" reliability issues all have fixes and are generally pretty cheap. i own several 6.5 powered rigs and work on them regularly, if you take care of the known issues with proven fixes and take care of them they are very reliable engines. If you neglect it and have it repaired by people with no knowledge of these engines you are going to have trouble and it is going to be expensive. Thats where their bad rap has come from. The last 3 6.5's that have come in for drivability issues have had fried or bypass'd oil pressure sensors. oh the horror, a $20 part failed, and they still all drove in. Reliabilty is just as important to the people out on the ocean running 6.5's in their boats and the men and women of our armed forces running them in hummers as it is to people in planes. My point was it is the exact opposite of what you would want in a plane, they are heavy low rpm engines and arent exactly compact.

last month i pulled the 250K mile 6.5 out of my suburban and transfered it over into my new 1 ton dually. the 6.5 in my s10 has over 150k on it. These things arent rolling over and dying like people on the forums would want you to believe. I got the 1 ton cause the guy ran it out of oil and spun a bearing then took it into a shop who put a new injection pump, ops, lift pump, glow plug relay, and ignition switch trying to make it run again.


Besides all that people put subaru 4 cylinders in planes and those are rod throwing head gasket blowing piles of shit.

new to diesels
 

Hi josh and everyone i have found a 98 chevy 2500 from a friend of mine with the 6.5 turbo motor its it a newly built motor with only 6k on it and a rebulit trans (has all paper work to go along with it). Motor still has a 1 1/2 on a warranty and mechanic will honor it even if i buy...it also has a fresh built front end including the steering box and brakes all the way around....... hes asking 6500 for the truck. Do you think this is a fair deal...im not going to be beating this truck to the ground just to pull a boat and an enclosed trailer every now and again... thanks for the help.....yogibear

4x4???

Yep 4x4 extended cab...has bed cap...new tires.....bas is the front seats are ripped up

sounds like a great deal if it runs and drives nice and isnt rusted to fuck. You could spend 6k on a truck with original engine/trans and unknown service history around here.

anytime i look at a 6.5 i always start it up and go underhood and look if the pmd is still plugged in on the side of the pump or if it is relocated and then open the air bleed on the top of the fuel filter and see if fuel comes out or if it doesnt and then the truck dies it has a lift pump/ops issue. good idea to look at the drivers side rear of the block for oil leaks. chances are the oil filter adapter is leaking and or the oil cooler line fittings are. then if it still has a vacuum system i give the waste gate arm a push and see if it holds against pressure, if it doesnt truck probably wont make boost and will smoke. then you need to be sure the trans goes into forward and reverse. if it does all that stuff its in ok shape. Always a good idea to make sure the balancer rubber is in ok shape.

Yea its a south Georgia truck no rust whatsoever

Yea its a south Georgia truck no rust whatsoever owned by an older gentleman who only towed a camper with it

So I'm looking for a short bus for use as a small camper, hauling kayaks, etc. Will never pull a heavy trailer. Cost to operate is a major concern, want good fuel efficiency for low driving costs. Looking at this:


Low mileage diesel Gmc short bus


Guy says it's a non-turbo 6.5, about 18-19 highway mpg. When I asked about how the engine has been maintained, he said it was the turbo versions that have problems not the non-turbos but I don't think this is true? I've been reading a bunch about 6.5s but there's a ton of conflicting info out there.


In a bus like this, what should I be looking out for in the engine? If I'm having to put a bunch of money into reliability issues, the fuel efficiency advantage disappears real quick.

And is the fact that this is in a low mileage bus that's probably never been used and abused by towing too much shit likely to decrease my odds of needing catastrophic repairs?