6.5 question.

[Thunder]

I really need a PU truck. I am thinking about getting a rattler. Found a 1998 GMC 1/2 ton SL 6.5 with only 42K on the clock. It is a really nice well cared for clean truck. It keeps saying Buy me!
I know a bit about the 6.2. but next to nothing about the 6.5. I have driven a couple of trucks with 6.5 in them and thought they were OK. Heard they have injection pump issues. Also heard the 98 and up 6.5s were the best because they had upgrades to them which addressed eariler problems. Is that true?
Do they get good MPG like the 6.2?
Any other problems with them? Anything i should look for when checking out the truck engine wise?
I have never really liked diesel but for some reason I am getting the bug to get one real bad. My wife really likes the truck too. She already said buy it if I want to.
Would like to hear pros and cons of the 6.5. I know they are not a powerhouse. But thats OK. I really dont tow anything very heavy. I am more interested in fuel economy and dependability.

Thanks.

 

[longbedder]

Like you already know they aren't duramaxes, but they are good engines and if you learn the tricks and care for them they'll last. The blocks/cranks can have the same issues as the 6.2 (main web cracking and crank breakage). The 98's with a casting number ending in 506 have piston oil squirters drilled in them which actually weakened the block and led to somewhat higher cracking probability. A fluidampr harmonic balancer and beefing up the bottom end with a stud girdle helps to mitigate these issues. You can check the CDR (tuna can looking thing) for sludge and water drips/vapor when running which would indicate a cracked bottom end.

The 97+ have the best production cooling systems for these engines.

The injection pumps have a pump mounted driver (PMD) which electronically controls them. The stock location for the PMD keeps it hot which is not good. The first thing to do would be to get a PMD relocation kit and keep that thing as cool as possible. Consensus is that relocation to the inside of the front bumper is the best spot and they'll be very durable there. Heath diesel sells a kit or you could make your own (it's just an extension harness and heatsink).

When you test drive it, put it in park while warm, bring it slowly up to 2k RPM, hold it 5 seconds, then back down to idle. It should be smooth throughout this range. Fluctuation may mean a worn out injection pump (which at 42k it shouldn't be). Also check the turbo for front-to-back play (should be zero) and side-side play (shouldn't touch the housing).

They do get very good mileage.

 

[Thunder]

Thanks Longbedder. That helps. looks like I may drive up and check out the truck and possibly buy it tomorrow. Its about 150 miles away up in Idaho at an equipment sales place.

 

[Thunder]

Well it looks like there is another forum here i will be hanging out in.
I always swore i would never buy a diesel... Now i know why mother told me not to swear.
Gotta admit i am really happy with this truck.. 1/2 ton/ with 3.73 14 bolt SF rear, 4l80E, HD Xfer case, basicly all 3/4 ton running gear. Gets better milage than my TBI K5. Drove the Blazer up to get my new truck. quite a diference between the 2. Like the 6.5 POWER.
Thanks again for telling me what to look for. so far so good. runs great. looks like the PMD relocation will be my first mod.
here she is.

 

[KirsL]

Nice find . That truck should give very good mileage. They do have pretty decent power the 6.5s, couple mods and they run even better. Soon you'll want to swap a diesel into your K5 .

 

[longbedder]

Nice!
I was a diesel newb until I got my first 6.2...now I'm on the road to the whole fleet being diesel.

 

[tRustyK5]

looks pretty clean!! Good score.

Rene

 

[Thunder]

Thanks guys. Yeah it is really clean. No rust! It is a city truck. It spent its life driving around Incline village at Lake Tahoe. maybe a trip to Reno or Sacramento now and then. Incline is a small town so that is why the low mileage.
It is a bare bones truck. No power locks, no power window, no stupid security chip in the ignition key or other BS whistles and bells. Has just the basics, radio, heater and AC. No carpet so it is easy to clean out.
Tore into it today to find out what it needed. Found out the lift pump was not working... I wondered why it seemed a little slow off the line. Had a choppy noisy idle too. Glad I got it fixed before it hurt the IP. I hope.
Runs way better now and pulls tire burnin hard off idle. Nice and smooth. I am excited to have a new project and build this engine up a bit... A 3" lift... 33" MTs... locker.... Hmm the list goes on.

 

[AJMBLAZER]

Nice score. You rust free guys make me hate you.

Just put 285/75R16 or 255/85R16 (33x11.25R16 or tall 33x10.5ishR16) muds on it and call it good. Lifting torsion bar IFS is bad.

The front is a half ton unit. Only the rear is the 3/4 ton stuff.