6.5 swap questions

[beardeddummy]

When I had my 97 c2500 with a 350 5speed and 4.10s. I had a buddy with the same setup with a 6.5 when he bought his mud truck he asked me to pull it because he didn't have the pulling power i did. not sure on any details of his truck. all I had was longtubes

 

[someotherguy]

I respectfully disagree, the only PMDs I have ever changed have been ones that the previous owner relocated to the intake or somewhere in the engine bay, a known failure point encouraged by a few less than reputable relocation kit sellers. The stock location ones and my relocated to bumper ones have yet to fail me.

I respectfully refer you to the reply just above yours where yet another 6.5 owner went through multiple PMD's.

What was your 6.5L Richard? IIRC it was kind of a project to start with, right? If a guy can start off with a healthy 6.5L it ignites an inner fire that cannot be put out. Buy a basket case 6.5L and not subdue and conquer it in short order, it will ignite an inner rage...

The truck had a basket case vibe, but only because it was a rusty old body - transplanted onto a more modern chassis and driveline. It was a '58 cab swap onto a '94 C3500. The engine had been rebuilt and the truck was a running/driving vehicle as-bought. My plan was to bag it to make it more daily drivable (it was a very extreme static drop) but that was it. It proved to be unreliable enough I was ready to convert it to mechanical, bought all the '93 stuff I would need to do it, and decided I'd get rid of it before it suffered any of the other 6.5 ailments they are known for.

That was the only 6.5 I've owned but I've known plenty of people that had them and had to listen to their horror stories. I had multiple customers at my salvage yard with them, as well. One thing for sure, it's easy to find 6.5 parts trucks with bad engines - more than any other GMT400 truck out there and that includes the 4.3 V6!

Richard

 

[GM Guy]

Much agreed Richard, lots of dead ones out there.

Most can be traced back to neglect though, non-functioning vac system not letting the turbo build any boost and engine dies of EGT related failure, plugged radiator and bad or cheapie t-stats crack heads, etc.

They dont seem to hold up to much neglect, they are a very maintenance dependent engine. But well maintained, they are pretty tough and moderately powerful.

I guess my statement to PMDs should have been clarified to applying to engines with good injection pumps. I have a theory that a dying IP will put alot more load on a PMD than a healthy one, and will kill any PMD, no matter the location, as it seems people who's 6.5L have a steady diet of PMDs will throw in the towel and get a new pump, then wont eat a PMD again.

I might get to prove that theory with my recent 500 dollar POS. prior to it, zero bumper or IP mounted failures.

@tanman_2006 on the PMDs you have replaced, have they usually been traceable to some other issue, and/ or a bad IP?

 

[RichLo]

wow, bringing up 6.5's is like asking what your religious beliefs or political views are. lol.

 

[90halfton]

wow, bringing up 6.5's is like asking what your religious beliefs or political views are. lol.

6.5 lives matter too.

 

[tanman_2006]

My pmd was intake mounted, then I cheaped out on a cable on a beater. Now they all have Leroydiesel cables and ssd heat sinks with a hole drilled and mounted in the bumper.

My 95 Z71 got 150k on a relocated d tech/flight system unit. It's ran in the heat, under water, in a blizzard, and in a stuffy corn field pulling irrigation units out of the mud. Power to weight ratio on that truck was impressive compared to my 97 Z71 350.

 

[tanman_2006]

They can also be a giant pain in the ass even spending the time, money and dedication that they REQUIRE to have a chance at reliability. I'd rather slam my manhood in a door than replace the 104K 6.5 in my dually but unfortunately it looks like my boys are going to be hurting for a long time.

You blow the 6.5?

Mine get the ever living piss ran out of them and I've blow 1 HG over the course of 4 trucks and 600k combined miles. I have bought 7pmds (still 2 new in box), 8 lift pumps (including 2 Walbro, a fass, and a raptor), 3 IP's (one still new in box), 1 water pump, 1 radiator, and 2 turbos. I will admit that I destroy NV4500's and clutches.

 

[GM Guy]

wow, bringing up 6.5's is like asking what your religious beliefs or political views are. lol.

Hello, do you have a few minutes to talk about our Save-ior of fuel?

 

[skylark]

You blow the 6.5?

Mine get the ever living piss ran out of them and I've blow 1 HG over the course of 4 trucks and 600k combined miles. I have bought 7pmds (still 2 new in box), 8 lift pumps (including 2 Walbro, a fass, and a raptor), 3 IP's (one still new in box), 1 water pump, 1 radiator, and 2 turbos. I will admit that I destroy NV4500's and clutches.

I had an exhaust valve failure. I pulled it down for an inspection and found cracks in the block. I have a 94 engine as well that came with a parts truck and it also has a failed exhaust valve. I bought a previous truck with a dead hole and it was a failed exhaust valve. Three different trucks and all failures were on #3 cylinder.

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[tanman_2006]

If that's not odd I don't know what is.

I have 2 Parts engines with busted cranks, a 599 and a 506. The heads were good on both other that where the 506 valves met the piston, the 599 broke the front snout and seems pretty in harmed, both Crack mains though.

I also have a non turbo 6.2 with a hole in the piston but that's more of a bad injector.

My personal trucks haven't had many issues really. Dependable, capable, and economical are words that come to mind. I plan to give the tbi 350 a chance to run along side my 93 6.5 and see if a modded 350 will hold up to a modded 6.5l.