6.5 Diesel Questions

[97PROSHOZ71]

I have some questions for 6.5 Turbo Diesel owners. I'd really like to have one, but I have heard mixed reviews on the engine itself, from being junk engines to being good engines. I'd like to have one not for power (which I understand they were not built for), but for the fuel mileage. Eventually I would convert it over to a Cummins or something. What are some things I should watch out for on these engines? What can be replaced or fixed to make them more reliable then people say they are? I'd just like some general information on the engine itself that I don't know about.

 

[skylark]

The later model the better! The 99.5-2000 has all of the factory cooling upgrades including the spin on fan clutch, HO water pump, dual thermostats and the 9 blade fan. The 96ish-98ish has issues with the metal and are prone to cracking in the webs. Relocate the PMD off of the engine, alot of guys locate theirs in the grill/bumper area. Ours is in the airbox. Get rid of every piece of the factory exhaust and the turbo. Diamond eye exhaust and a holset or knock off work well. The 6.5 isn't a power house. We have pulled 18.3-18.7mpg @ 62mph but that goes in the toilet at any faster speed. We do have 4.10's though. Truthfully, when the 6.5 dies a cummins will go in its place but as long as you aren't planning on drag racing it then you will do ok.

 

[97PROSHOZ71]

Good information to know! I didn't know it changed so much in the later years!

 

[goobs]

i loved my 94! 93 and before have mechanical injection pump. imho if you plan on swapping a cummins in, get a 93 w/ a manual trans. this will make the swap a million times easier.
im currently swapping a 12v in my 94.

 

[88GMCtruck]

Yeah, 99+ is the route to go. And FWIW Skylark, early 99s had all the upgrades too, my 99 was built in Feb and it had all the upgrades. 99 is a crossover year so if it was built in 98 as a 99 model it might not have the best of the best.

Skylark covered most of what you need to know. Here is my $.02
-PMDs are issues on all the electronic injected trucks. Get a spare and carry it with you, they can fail anytime.
-Even the later blocks have cracking issues, particularly in #8 cylinder.
-if your ever going to tow with it, get a EGT and Boost gauge.
-A-Team turbo is a great aftermarket turbo designed specifically for the 6.5L. I had one and loved it, very even power.
-Head gaskets can fail if the motor gets too hot, which is easy to do without an intercooler/EGT gauge.
-Harmonic balancers need checked, and replaced if getting dry rotted. If it goes you'll likely loose a crankshaft.
-Injectors are another good item to be serviced. If one sticks it'll put a hole in a piston. I've seen this happen twice in the past 2 years.

If you really want some good 6.5L info, there is a forum I'm part of were many 6.5L guys are at. thetruckstop.us

 

[97PROSHOZ71]

Thanks a lot! As far as I can tell they don't seem to be as bad as people say they are, they just must not know how to take care of them. I'll take a look at that forum too.


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[goobs]

I second truck stop. Great forum!

 

[West Mi Mudder]

I absolutely love my truck, and have no regrets getting it to replace my 1/2 ton. It has yet to leave me stranded. (yes, ive only owned it for a few months) Starts up every morning, even when its only 20 degrees and wasn't plugged in the night before. Has been getting about 17mpgs during the cold months, and was closer to 20 when it was warm out. If you replace the key components, like others have stated, they are great trucks. Many people that talk crap about them, havent owned one, or are trying to compare them to a cummins. Mines got about 290,000 miles, was used and abused its entire life, and still gets many compliments. Buying a used vehicle is difficult. Look at ChrisAU for example. He was in search for a mint gmt400, and finally thought he had found it. But turns out, it had its own problems. Every vehicle will have its quirks. If you take good care of it (which im sure you would with the looks of your current vehicle) im sure a 6.5L would last you quite a while.

 

[Darkrider]

Honestly Ty...if you take your time to search for a nice decent condition 6.5 powered truck you will prob not want to swap it to Cummins. As for the updates to the cooling system they can be added to the older engines as well. In fact im giving some serious thought to the idea of updating to the newer serpentine set up to allow me to run dual alts on Vegas.

 

[96-1500]

They get trashed way more than they deserve. I think that's because they are lacking in the "vroom-vroom" department, however as you said that isn't what they are designed for. You can't compare them to a Cummins or International. That's like comparing a 4.3 to a 454...different design, different purpose, different performance.

Personally I'd probably go for a mechanical one or an old 6.2 (I also would take a TBI over a Vortec any day of the week, call me crazy if you want). I like simple engines that are easy to fix.