Quoting myself below.
Full disclosure. I have 3 6.5 engines currently. One is junk (more than usual), another is in our 3500hd and the last one is a 6500 Opitmizer that is on a stand in my garage. I have a full extra set of sensors, 2 spare turbos and 2 spare PCMs.
I've had 3 engines with major but repairable mechanical damage under 125k. One was my personal truck that went from 81k to 104k before it ate a valve. Another was a meticulously maintained cream puff that had a valve failure at 79k. The last one I don't know the history on but it had a valve failure too but when I pulled the pan it didn't have sludge but there were more cracks showing than there are homies holding their pants up, it had 124k. May they rest in pieces.
I've had many electrical issues as well. Most were PMD or boost related. I also seem to go through AC Delco starters every 15-20k.
I don't trust these engines. Unfortunately I can't afford a 6bt/Allison A1000 6 speed/NP261xhd so I'm stuck building our 3500hd with the 6500 Opitmizer, billet crank pulley, fluidamper, HO water pump, Duramax fan, dual thermostats, ARP head studs, thicker head gaskets to reduce compression, Flowmaster exhaust crossover, Diamond Eye exhaust, HX40 turbo, high flow upper intake, Bosch glow plugs, real Bosch marine injectors, "feed the beast" mod on the filter assembly, Hayden HD fan clutch, Leroy oil cooler lines, air to water intercooler, tuned PCM and probably more that I'm forgetting. I already have all of the parts above.
I'm hoping to get rid of my gambling addiction every time that I turn the key and that all of these upgrades gives me a more reliable engine. I still won't trust it.
This is a quote from me when someone asked about the 6.5.
As a 6.5 owner, I would like to give you this advice. Get a rabid squirrel to chew on your left nipple. Have an opossum rip your right nipple off. Get into a fist fight with a kangaroo on meth. Piss off a rattlesnake with an under bite to the point that it knaws on your manhood to the point that if you ever pee through your swollen member again that it works like the water sprayer in the vegetable aisle. Then get r@ped repeatedly by an entire family of silverback gorillas with sexually transmitted diseases. Finally go to sleep naked in a prison without lube while handcuffed.
Owning a 6.5 is worse than that.
My ass still hurts.
Quoting myself again...
The 6.5 was based on the 6.2 which didn't have enough power to do much of anything but The fine folks at General Moturds decided to "compete" with the 5.9 Cummins powered Dog and the upcoming 7.3 Powersmoke. To do that they slapped an inefficient turbo on a larger displacement engine with crappy metallurgy. Then they used a cooling system that wasn't up to the task. They also rushed the electronic injection pump using, in my opinion, an underdeveloped control module (PMD). There are notorious for PMS failures (was that really a typo?...), cracked blocks in the main webs, cracked heads, overheating cylinder #8, injection pump issues, failed oil pressure sensors, complete cooling system failures, harmonic balancer failures resulting in sheared crankshafts, a crappy rubber balancer pulley, the wastegate system consists of failed vacuum pump, cracked plastic lines and solenoid failures, the turbos used were really undersized for their application resulting in high drive pressures causing excessive heat leading to cracking in the heads and valve failures plus additional heat to the already overtaxed cooling system. Oh, I almost forgot that oil cooler lines like to fail in dramatic fashion. Don't believe me? Just Google 6.5 and everything that I mentioned.
I personally have owned 4 6.5 powered trucks. One I immediately sold. Two came to me with low mileage, 79k and 124k and both of those had valve failures. The 79k one had meticulous records including the additive and fuel mileage of every tank of fuel since new, every light bulb, oil change and truck wash. The fourth truck was my own personal truck and the #3 exhaust valve failed taking out the head, piston and possibly the rod as well. May it rest in pieces at 104k...
I'm stupid enough to put a 6.5 back in my truck because I don't have Cummins swapping cash and I had already bought new hoses, glow plugs, injectors, upgraded turbo, mandrel bent crossover and more prior to the engine failure. Not too long ago I came across an Optimizer for a reasonable price. Do I trust it? NOPE! I've addressed every single issue mentioned above but prior to it getting back on the road I will renew my AAA membership.
