Dare I buy a 6.5 diesel???

[City Slicker]

I have never owned a diesel and I am currently looking at buying a 97 K1500 GMC 6.5 td with 110k. I have read many posts on the problems that these motors have, from faulty IPs and FSDs to (till most recently) cracked blocks.
Do these motors all have that much trouble or do just bad ones end up in the forums? Would a 5.7 be a more reliable motor?
I would really like to have the diesel but if I have to spend thousands of dollars for new blocks and IPs I won't be able to aford it.
Thank-you for any input that you guys can give me.

[damork]

I believe the problems associated with the electronic pump are far fewer than they started with. I had problems and after installing the last pump, I have 85k on it and it is working well. Just about anything can have weak points, and after nearly unloading mine around 100k, I decided to hang with it and am glad I did and am now over 200k.

Stay in touch on this site, learn what proper maintenance is for these and you should do well. I find the following the most important with maintaining my truck.

1. Clean grounds for the wiring.
2. Unquestionable battery power with clean connections - keep them clean.
3. Buy good fuel - consider a water trap filter prior to the lift pump (30 micron Racor is what I added). There is a major difference in how my 6.5 runs with good vs bad fuel.
4. DSG timing gears make a big improvement in starting, smoothness - the change is noticeable.
5. Relocating the PMD/FSD in front of the drivers side battery will help longevity.
6. I've used Stanadyne blue in every tank.

Those are a few key things I have followed along with keeping fresh fluid in all systems, including power steering, transmission, transfer case, diff, radiator, as well as the engine oil.

[john8662]

Being a 97 is a definite plus, this is the first year for the dual stat cooling and hi-flow water pump. So the engine in that truck has had a better time keeping cool that previous models did. The previous model 6.5TD's were undercooled, which leads to further problems down the road (even if upgraded, as I found out!) The 97 year model also has the better air box design, so it has a better chance of breathing clean air verses eating dirt. If the truck has been well talken care of, and doesn't have a ball in the bed or 5th wheel holes in the bed, its worth a shot.

[Tough Guy]

Well...since its a 1500 series it may not have had its guts pulled out like an HD possibly would. 110,000 miles isn't too bad if maintenance was done properly. I currently have 160,000 on mine a hard 160K I might add.

However, I also owned a 1998 Silverado 1500 with the 5.7L it was a great truck and got as good of fuel mileage as my 6.5L does and with care and maintenance its considered a 200,000 mile engine. I had 80,000 miles on it when it was totaled in an accident, then I replaced it with my current 6.5L


Cheers

[City Slicker]

If a IP or a FSD would go I would be able to handle that but if a block would crack, that would be more than I would be able to afford to fix.
I have read that the 97+ models have made some changes that make the block suseptable to cracking. Plus the new block cracking poll has made me a little nervous about these motors.
Is this a hit and miss kinda thing or does it only happen to motors that have been abused or have had to do alot of pulling?
Are there any warning signs to look for when buying if there is a possible crack?
Thanks again for the replys, it really helps me to make a decision on a truck. I know I will buy a 96-98 K1500 I just need to decide between a 5.7 or 6.5td.

[JTodd]

When reading forums such as The Diesel Page, bear in mind that their main purpose is help with problems. Therefore, most discussions are about the various problems and possible solutions. I would estimate that the ratio is at least 20:1, problems vs upgrades, etc. This certainly should not be taken to mean that there are 20 bad trucks for every one without problems. We just don't tend to talk about our trucks that give us literally thousands and thousands of trouble free miles - frankly it would be boring.

Diesel engines have their problems, as do gassers. Just different parts. We have our FSD and they have their MAS. Have this possible purchase looked over by a reputable diesel mechanic - they should know what to look for.

[curmudge1]

My $.02...

Think also about what you can & are willing to do yourself or if you have a mechanic available to do the extras, for instance the timing gears.

I don't do so much myself, but I did install Kennedie's FSD cooler when I had stalling symptoms, and it's been a month & a couple of K miles & no stalls since.

I had a 1990 K1500 extended cab long bed with the 5.7 gas & lightweight manual trans (Getrag 5-spd, iirc, I don't recommend it) that had 262K miles on it when I sold it vs. 248K miles so far on my 1994 Blazer with 6.5TD. And that did get almost as good mileage with the 3.42 diff gear as my 6.5TD Blazer with 3.73 diff gear.

See if you can have a dealer run the VIN to see if the injection pump has been replaced... they don't last forever & if you take to a GM dealer out of warranty, it'll probably be around $2K or so, depending on whether/how much the dealer discounts.

[patrick m.]

im just shy of 200k miles on my 6.5, and i drive it hard.
I have the original engine, and it runs great.

so not all of them crack.
not all of the ones that have been serverely overheated crack.

do your homework, get the 6.5, you will be glad you did.

(this is the first diesel vehicle for me, i'll never be without now) ;)

[moedog]

IVE NEVER KNOWN ANYONE WHOS INJECTION DID NT QUIT ON A 94 UP. AND IVE MET MANY WITH NEW ENGINES AND FOR SALE SIGNS IN THEM.
IF YOU CAN GET A 6000 GAS, IT WILL PULL AS MUCH OR MORE WEIGHT AND NOT OVERHEAT. THE OLDER 350 GAS MOTORS ARE REALLY CHEAP TO MANTAIN AND REPLACE AND RUN COOL. BUT IF YOU GOTTA HAVE A 6.5 DIESEL BE SURE YOU KEEP A MEMBERSHIP WITH THE PAGE CAUSE YOU ARE GOING TO NEED IT!!!!!!!!!!!!!!!!!!!!!!!!!!!

[City Slicker]

How does the 6.5 compare to the 5.9 Cummins and the 7.3 Power Strokes as far as reliability goes?.

If you compare these motors frome 94-00, apples to apples how do they match up?

Do these motors have problems with blocks cracking, IPs failing etc.? or are they just in general a more reliable motor?

I guess what I'm asking is, all motors have problem areas, was the 6.5 exeptionally bad or was it just a so so motor that put out a few lemons?

Thanks Again

[Ryan Colley]

I don't know much about the cummins and powerstrokes vs. the GM 6.5L, but I will throw in my 0.02$ re. the gas vs. diesel...

My first truck was a '92 1/2 ton with a 350, which I traded on a '95 K1500 6.5 L extended cab...big mistake. After three injection pumps, two lift pumps, countless oil pressure switches and the ever famous PMD, I sold the POS (taking a huge loss), took the left over cash and bought a 1988 K2500 with the 6.2L. It has been reliable, but still has issues, the transmission in particular has never been right.

Although I am keeping my 6.2, I have partially switched back to gas, having bought a 1991 with a 305. Its got over 300,000 kms on it, runs like a charm, costs nothing to maintain...and sure if the engine goes I can put a rebuild in for the same price as a new injection pump!

I will NEVER buy another 1994+ GM diesel. It put me in the poorhouse. RUN as fast as you can.

Just my thoughts.

[Ryan Colley]

BTW - my 305 gasser gets 15 mpg, my 6.2 gets about 18 mpg...with the price of diesel having shot past gasoline...there is no real economic advantage to driving the diesel.

If you factor in IP costs, and the ever looming possibility of craking a block....well it just doesn't make $en$e.

But there is something to be said for driving a diesel....

[rjschoolcraft]

Even with the troubles that I've had, I would buy another one. I'd be careful in which one I bought, but I'd do it again. Once you understand them, they're not so bad. Hey, I'm in the process of gathering parts to build a new one right now.

[markrinker]

This is a common question - and a good one.

Remember you are asking a group of dedicated enthusiasts, who choose to overcome the shortcomings of the 6.5 engineering through their own research, wrenching and dollars spent.

Bottom line in my opinion are three questions:

1) Do you want to learn alot about diesel engines?
2) Do you need a stronger tow vehicle than a 5.7 gasser?
3) Do you have the willingness to troubleshoot and repair, and/or financial resources to overcome the failures of the 6.5TD?

If you answer yes to 2 or 3 - do it.
If you answer no or maybe to 2 or 3 - buy a gasser.

[David_Jennings]

Something else to think about is initial cost. Because these trucks have such a sour reputation, they are cheaper. I bought my '99 for thousands less than what I would have paid for the same truck with a gas 350. Second, I think you should pay attention when your truck talks to you: fixing something before it breaks is always cheaper and more pleasant than paying a dealer after a tow. Also, for what it's worth, of course the Cummins and Navistar are better engines; unfortunately, they come in trucks that many consider to be inferior to those made by GM. Many have replaced their engines; but from what I read, those that have done it the right way, using advice from this page, are thrilled with the results. My truck came with 100,000 mile warranty on the engine, and 120,000 on the pump. That helped.

[Fieldoc]

The 6.5 in stock form does not compare to the 7.3 powerstroke. As a former 6.5 owner and powerstroke owner the navistar motor is much better, just a lot more expensive.

[markelectric]

The 12 valve Cummins are a good bit more relilable than a 6.5. The 24 valve Cummins eat injection pumps probably as fast or faster than 6.5s at a higher replacement cost. seems they need extra fuel to keep them cool too.
That being said, I have 2 Cummins trucks because of some of the insane loads I tow. I love the feel of the power pulling the trailers but absolutely HATE the sit and the cabs of the Dodges. We still have a 95 Suburban that is showing about 340,000. never has had much done to it.I replaced the injection pump at about 3000,000 and promptly replaced 3 more right after that but my rebuilder admited a bunch of problems and covered allthe extra costs. The suburban is much easiear to drive and WAY more comfortable to sit in than the Dodges.
I would rather have my butt in a Chevy with my foot pushing on a Cummins but untill I can buy one that way I will keep wishing.....

[City Slicker]

Is there one year for the 6.5 that is more realable than the other?
I have been reading posts where guys are avoiding the 97+ models with duel thermostats and the larger oil spay holes.
Wasn't that supposed to be an improvement? Did these mods solve the problems of over heating or did it just start a new problem with cracking? Should I be looking for a pre 97 6.5 without the "improvements"?

[Jcolg]

City - You have raised an interesting question for me. One month ago I purchased a 1997 6.5 TD 2500 SLX entended cab. It has 130 K miles and was a one owner. This truck runs great and is the best driving truck I have ever owned. However, image my surprise when I came to this site looking for some basic info, and finding the "Cracked block" poll staring at me every day. I have come to learn, that 97 was the year that they upgraded the cooling system, while at the same time it appears that other changes were made that may have made the blocks weaker in some areas. None of my mechanic friends, and I know several knew anything about problems with the blocks when I took the truck to them for their opinions. They were aware of IP pump issues, but felt that if the truck was running well at 130K, then the pump had probably already been changed and the new ones were fine. One mechanic I know manages a city yard, where they use a mixture of 6.2 and 6.5 diesel powered vechiles, and he never mentioned a problem with a specific year or engine type. I purchased this truck because it was the newest, lowest mileage one that I could afford, and BTW in my area, these truck are not thousands of dollars less then their gas equivalents. I fact they are about 2k more. So I guess time will tell as to whether this ends up being a good vechile for me or not, however after visiting this site and others, I still probably would have bought this truck. The diesel sound and power is addictive and I think I'm already hooked. I do have a 6 month engine warrenty, so I'll cross my fingers, keep reading and learning and see what happeneds.

[CareyWeber]

Originally posted by City Slicker:
I have never owned a diesel and I am currently looking at buying a 97 K1500 GMC 6.5 td with 110k. I have read many posts on the problems that these motors have, from faulty IPs and FSDs to (till most recently) cracked blocks.
Do these motors all have that much trouble or do just bad ones end up in the forums? Would a 5.7 be a more reliable motor?
I would really like to have the diesel but if I have to spend thousands of dollars for new blocks and IPs I won't be able to aford it.
Thank-you for any input that you guys can give me. City Slicker,

I have a 1997 GMC K3500 CC SRW truck and it's great I have +187K US miles on my truck and I have not had to open up the enginee for any enternal wrenching. I had the IP replace by GM at 99K miles which was down under warrenty. Other than that I have replaced the lift pump, glow plugs, pitman arm, door handles interior exterior, door hinge pin bushings, low beam head lights, OPS, belts, idler pulley bearing, alternators, batteries, battery cables, and oil cooler lines all of these items are IMHO maintance items except the door handles.

I had one issue where it was stubbling, but that was caused by wires that were rubbed through.

I'd say this though I don't think the diesels are cheaper to run unless you drive it beyond 250K miles, or you are always towing.

Carey

[ 01-30-2005, 05:25 AM: Message edited by: CareyWeber ]

[Cowracer]

Every drivetrain has a weak spot.

6.5's have IP problems...
Early 'strokes have cyl erosion/cavitation problems...
Early 6.0 liter 'strokes injectors dribble fuel (eventually costing a whole motor)...
Early 6.6 Dmaxes had injector troubles and head problems...
Dodges of every stripe have tranny problems...

454 GM gassers crack exhaust manifolds like clockwork...
305 GM gassers grind off cam lobes...
400 GM Smallblock gassers crack cyl walls...

5.7 GM diesels blow out the bottom end...
4.6 gasser fords leak at the intake manifold and blow sparkplugs (threads and all) out of the heads.

Early Ford gassers had the infamous "Brain box" on the fender that would die and leave you stranded.
Early Mopar Gassers had a electronic ingnition module that would do much the same.

And the list goes on and on ad infinatum

No matter what you drive, there will be a design problem that will bite you in the butt sooner than later. At least with the 6.5 you know the problems are (mostly) limeted to a couple of areas and there are steps you can take to address them.

You also know that the tranys and rear ends are solid as a rock, the cabs are comfortable and wont shake to pieces and the front ends (while not perfect) are better than dodge and fords.

The 6.5 was tarred with the same brush as the 5.7 diesel (which arguably deserved its evil reputation). I am convinced that had the 5.7 not been such a poor product, the 6.5 would not have a bad rep amongst those who dont own one.

Tim

[Mike Pope]

We own 3 brands of diesels..........

The GM 6.5 is the only one that gives us a constant fear of not getting where we are going........or stalling in an intersection.

I know we will NEVER own another. I'm not even sure at this point if I would EVER buy another GM product period. Our diesel suburban has been the most unreliable vehicle we have ever owned. Sure, GM extended the warranty on the pump......but the warranty really depends on your dealer. We were told.........well, we really can't blame the pump without first replacing this, that, the other, and a couple more parts, which, of course aren't covered by the warranty. So we shell out the money for all of that and guess what...........still same symptoms. They give us more BS and say they still can't replace the pump under warranty until blah blah blah. Basically they gave us the run around until we were past the 120k mark, at which point I finally bought a pump on e-bay and replaced myself..........and GUESS WHAT.........problem solved...........well, temporarily anyway.

Make of that what you will. Just don't come back to say you weren't warned!!!

[JohnC]

Witness the lightning rod syndrome. No one (OK, no one but Carey) posts "another day of trouble free driving today..."

Imagine how long this thread would be if they did! ;)

[ 02-01-2005, 05:58 AM: Message edited by: JohnC ]

[City Slicker]

I have a read a little about a some kinda "stud stabalization" to prevent block cracks in the 6.5s. Has anyone heard of this or tryed it? Does it actually help anything? Is this something worth trying as a preventitive measure?

With all the talk about cracked blocks I've seen this mentioned very little.

Thank-you for your replys

[CareyWeber]

Originally posted by JohnC:
Witness the lightning rod syndrome. No one posts "another day of trouble free driving today..."

Imagine how long this thread would be if they did! ;) John,

Hey I thought thats basically what I said. ;) :D

Carey

[Tough Guy]

Yes, there are girdle kits for the bottom end.

There are also "splayed" main caps available too.

Cheers

[Bobbie Martin]

Originally posted by Mike Pope:

The GM 6.5 is the only one that gives us a constant fear of not getting where we are going........or stalling in an intersection.
Our diesel suburban has been the most unreliable vehicle we have ever owned. Wanna fix it? Get rid of that DS4 and fit a DB2. Problem solved.