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:

---AutoMerged DoublePost---

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"?






Sent from my iPhone using Tapatalk

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

---AutoMerged DoublePost---

[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?

;)


Sent from my iPhone using Tapatalk

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