GMC / Chevy mid-90's 6.5 diesel 3/4 ton pickups

[jeep-N-montero]

I'm seriously looking at a 1995 k2500 with manual transmission and low miles for our tow rig and was curious if any of you have had personal experience with them? I have read up on the overheating issues they can have when towing heavy loads and contacted Heath Diesel Power about power upgrades. Anything else I should be aware of when I go look at it?

 

[Rot Box]

Search around here I have a few posts a mile long with my experience with them.

The PMD/FSD isolator from Heath (and only Heath) is a must have upgrade that would be on the top of my list. If you haul heavy get the 97-current dual t-stat housing and higher gpm water pump (the water pump is available at any auto parts store) or you will melt the engine from the inside out. Check the harmonic balancer on the front of the engine for cracking where the rubber meets the steel. When these come apart it takes the crankshaft out with it. Get familiar with how to change the fuel filter. You can troubleshoot a faulty lift pump this way if you know what to look for. The OPS (oil pressure switch) are known to fail which cuts power to the lift pump causing hard starts and power loss at higher rpms. Its a $20 part--worth keeping a spare.


As for power 4.10 gears aren't a deal breaker but see if it has them they definitely help. A 3" free flowing down-pipe (the stock piece is kinked off horribly), a #9 resistor for the injector pump (get with Heath on that one also) and removing the snorkel between the air box and fender will make a worthwhile difference in power and lower egt's. If it's the heavy gvw 3/4 ton you'll gain an "F" vin engine and a NV4500 trans and that package does well for what they are once they're uncorked. If its a light 3/4 ton they should still have the NV4500 however they will have an "S" vin with a different pump calibration and some other restrictions on the engine netting less horsepower/torque. I could pull on my brothers 454 with my F-vin in the canyon with similar loads to give you an idea on power. A freind has an S-vin K2500 and it feels like a small block 350 under load :-\

Some years are better than others in terms of reliability. My brother had a 95 with 550K original miles before a rod let loose

 

[jeep-N-montero]

Search around here I have a few posts a mile long with my experience with them.

The PMD/FSD isolator from Heath (and only Heath) is a must have upgrade that would be on the top of my list. If you haul heavy get the 97-current dual t-stat housing and higher gpm water pump (the water pump is available at any auto parts store) or you will melt the engine from the inside out. Check the harmonic balancer on the front of the engine for cracking where the rubber meets the steel. When these come apart it takes the crankshaft out with it. Get familiar with how to change the fuel filter. You can troubleshoot a faulty lift pump this way if you know what to look for. The OPS (oil pressure switch) are known to fail which cuts power to the lift pump causing hard starts and power loss at higher rpms. Its a $20 part--worth keeping a spare.


As for power 4.10 gears aren't a deal breaker but see if it has them they definitely help. A 3" free flowing down-pipe (the stock piece is kinked off horribly), a #9 resistor for the injector pump (get with Heath on that one also) and removing the snorkel between the air box and fender will make a worthwhile difference in power and lower egt's. If it's the heavy gvw 3/4 ton you'll gain an "F" vin engine and a NV4500 trans and that package does well for what they are once they're uncorked. If its a light 3/4 ton they should still have the NV4500 however they will have an "S" vin with a different pump calibration and some other restrictions on the engine netting less horsepower/torque. I could pull on my brothers 454 with my F-vin in the canyon with similar loads to give you an idea on power. A freind has an S-vin K2500 and it feels like a small block 350 under load :-\

Some years are better than others in terms of reliability. My brother had a 95 with 550K original miles before a rod let loose

It is an "F" VIN, Bill at Heath asked me about it and the seller gave me the VIN. Too bad you are so far north or I would have you go look at it with me. Thanks for the great info. I'm excited and my wife likes the truck even before going to look at it, having only 140k miles helps too.

 

[SLC97SR5]

Yeah, Andrew has some IDI knowledge.

As long as you understand what you are getting, it sounds like a decent rig. It will NOT hang with the modern DI diesels but will return decent mileage.

Get a set of gauges and get truckin'. Turning higher rpms will help with coolant temps and egts.

 

[jeep-N-montero]

It will take some getting used to when I drive it, been a few years since I drove a longer wheelbase truck.

 

[jeep-N-montero]

Search around here I have a few posts a mile long with my experience with them.

The PMD/FSD isolator from Heath (and only Heath) is a must have upgrade that would be on the top of my list. If you haul heavy get the 97-current dual t-stat housing and higher gpm water pump (the water pump is available at any auto parts store) or you will melt the engine from the inside out. Check the harmonic balancer on the front of the engine for cracking where the rubber meets the steel. When these come apart it takes the crankshaft out with it. Get familiar with how to change the fuel filter. You can troubleshoot a faulty lift pump this way if you know what to look for. The OPS (oil pressure switch) are known to fail which cuts power to the lift pump causing hard starts and power loss at higher rpms. Its a $20 part--worth keeping a spare.


As for power 4.10 gears aren't a deal breaker but see if it has them they definitely help. A 3" free flowing down-pipe (the stock piece is kinked off horribly), a #9 resistor for the injector pump (get with Heath on that one also) and removing the snorkel between the air box and fender will make a worthwhile difference in power and lower egt's. If it's the heavy gvw 3/4 ton you'll gain an "F" vin engine and a NV4500 trans and that package does well for what they are once they're uncorked. If its a light 3/4 ton they should still have the NV4500 however they will have an "S" vin with a different pump calibration and some other restrictions on the engine netting less horsepower/torque. I could pull on my brothers 454 with my F-vin in the canyon with similar loads to give you an idea on power. A freind has an S-vin K2500 and it feels like a small block 350 under load :-\

Some years are better than others in terms of reliability. My brother had a 95 with 550K original miles before a rod let loose

After I perform the cooling upgrades, the Heath programming PROM, relocate the MPD module, a good exhaust with down pipe, and air filter do you think I will be good to go then?

 

[jeep-N-montero]

Any other input?

 

[mbryson]

Most of us have avoided them. There's a lot of info and even some forums that support the "advantages" of the 6.5L. They aren't quite the catastrophic issues a F*rd 6.0L would have, but A LOT of the 6.2/6.5L got swapped to gas motors because the owners were tired of dealing with them.

 

[Unimog]

I don't have any personal experience with them, but after dealing with issues alluded to above, how much are you really going to save over a proven old powerstroke? I personally favor GM products, but talk mid-90's diesel pickup and that is what comes to mind. I know this probably isn't much help...

 

[jeep-N-montero]

The truck I'm looking at has only 79k miles on the engine and is all stock, passed safety and emissions 2 months ago, new batteries and glow plugs, 2 sets of wheels/tires, never towed more than a smaller boat and in-bed camper, and is well maintained with a very clean body and spotless interior. The truck will be our tow rig and will become our fishing and camping vehicle, so the IFS is favorable for the dirt roads and smoother ride on pavement when compared to a 90's solid axle Dodge or Ford. For $1k I can add 80hp/160tq reliably once I upgrade/update the cooling system and will pick up about 2mpg in the process. If this were going to be a 100% tow rig that only sees the road 1-2k miles or less when towing the Jeep to Moab I might consider a V10 or bigger V8 with a manual.

 

[mbryson]

The truck I'm looking at has only 79k miles on the engine and is all stock, passed safety and emissions 2 months ago, new batteries and glow plugs, 2 sets of wheels/tires, never towed more than a smaller boat and in-bed camper, and is well maintained with a very clean body and spotless interior. The truck will be our tow rig and will become our fishing and camping vehicle, so the IFS is favorable for the dirt roads and smoother ride on pavement when compared to a 90's solid axle Dodge or Ford. For $1k I can add 80hp/160tq reliably once I upgrade/update the cooling system and will pick up about 2mpg in the process. If this were going to be a 100% tow rig that only sees the road 1-2k miles or less when towing the Jeep to Moab I might consider a V10 or bigger V8 with a manual.

Well, you asked for input. I don't think there's much to give as almost no one here has had one. I don't know that I'd buy it. IF I did, I'd browse some of the aforementioned forums and decide if the "issues" that platform had will work for you.

It might be totally fine for what you want to do with it. For me, I wouldn't take the risk and would accept the crappier mileage of a known quantity gas rig (7.5L F*rd or 7.4L GM) or go to a 7.3L F*rd truck. I wouldn't buy the GM 6.5L diesel. Maybe I'm missing out?

 

[Greg]

I looked long and hard at the 6.5 Detroit diesels.... the conclusion I came to was that for the money, I'd rather have something else. The aren't the most reliable diesels and have several, huge known issues. There is a reason most people avoid them.

 

[Rot Box]

After I perform the cooling upgrades, the Heath programming PROM, relocate the MPD module, a good exhaust with down pipe, and air filter do you think I will be good to go then?

I'd say the PMD cooler and upgraded cooling (if you're towing) are mandatory. The other stuff adds performance to a motor that is very choked off from the factory

 

[Gravy]

relocated pmd, 4.10 gears (they like to rev) #9 resistor mod, spring and wingnut turbo wastegate mod.
Look up my posts on them. Had one. Liked it. Killed it.

 

[I Lean]

I drove a pretty new one to California and back, towing a truck....partway through the trip I had to start adding coolant every fuel fill--turned out a cylinder head cracked, IIRC. (or maybe a headgasket...something that cost the owner around $2K to fix, anyway)

 

[camicaztoy]

i had a 94 k3500, had the 373 gears, did the pmd cooler and #9 resistor mod. had really good luck with mine. had to replace the throttle pedal at about 125k but other than that no problems. pulled a gooseneck with 2 crawlers often, no over heating issues. steped up to some 285's. that helped my fuel milage a bunch. consistenly in the mid teens towing, low to mid 20's hyway. traded up becuase i wanted a duramax and a bigger cab.

 

[mombobuggy]

I always liked the G.M. 6.5 and even the 6.2. they are from an era when people did not expect so much from a one ton pickup and used the way they were intended to be used you can get a lot of service from them. i maintained a fleet of them for an excavator and some of them had over 300000 miles on them sometimes they had been updated to a 6.5 by then but they were driven hard by people who did not care much about the trucks often loaded down with excavator buckets utility beds or both they went through brake pads and glow plugs which were easy to test and replace. and some times injector pumps but we always had a parts truck to strip. starters sometimes. overall good durable trucks. And I do not buy Chevy trucks very often. They certainly outlasted the gas motors of the day and got decent mileage back when diesel fuel was cheap. I think you should try to get two of them and use one just for parts. Just my opinion.

 

[jeep-N-montero]

I bought it over the weekend, should be starting a "build" thread when warmer weather returns.