Taking a cue from how things were written up for the gas versions of our trucks figured it was time to do something similar for the Diesels. This thread will contain common upgrades to the 6.5 powered trucks and eventually some setups to bump up the performance. Lets start with a bit of history of the engine itself Quoted from Wikipedia 6.2L The original 6.2 L (379 cu in) Diesel V8 was introduced in 1982 for the Chevrolet/GMC C/K trucks and was produced until 1993. The 6.2L diesel emerged as a high-MPG alternative to the V8 gasoline engine lineup, and achieved better mileage than the General Motors 4.3L V6 gasoline engines of the 80s, at a time when the market was focused on mileage more than power. Applications 1982–1993 Chevrolet/GMC C/K 1992 - 1993 AM General Hummer H1 198x - 1993 AM General HMMWV GM version of the CUCV 1982-93 Chevrolet Van Specifications Engine RPO Codes: LH6 ('C' series, with EGR) and LL4 ('J' series) Displacement: 6.2L / 379 cu in Bore x Stroke: 3.98 in × 3.80 in (101 mm × 97 mm) Block / Head: Cast iron / Cast iron Aspiration: Natural Valvetrain: OHV 2-V Compression: 21.5:1 Injection: Indirect Horsepower / Torque (at start): 130 hp (97 kW) @ 3,600 rpm / 240 lb·ft (325 N·m) @ 2,000 rpm Horsepower / Torque (at final): 143 hp (107 kW) @ 3,600 rpm / 257 lb·ft (348 N·m) @ 2,000 rpm Horsepower / Torque (army): 165 hp (123 kW) @ 3,600 rpm / 330 lb·ft (447 N·m) @ 2,100 rpm Max RPMs: 3,600 Idle RPMs: 650 + or - 25 6.5L The 6.5 L (395 cu in) version was introduced in 1992 to replace the 6.2. Most 6.5s are equipped with a turbo. This engine was never meant to be a power and torque competitor with Ford/International and Dodge/Cummins, but rather a simply designed workhorse engine that made credible power, achieved decent fuel economy and met emissions standards in half-ton trucks. The Duramax 6600 replaced the 6.5 in light trucks beginning in 2001 and the C3500HD medium duty cab and chassis (replaced by C4500 Kodiak/Topkick) and vans beginning in 2003, but the 6.5 (6500 Optimizer) is still produced by AM General for the HMMWV. There are several GM 6.5 liter diesel engine production options. The Turbocharged L56, (VIN "S") was used in most light duty 3/4 ton (2500) Heavy duty 3/4 ton and 1 ton trucks used the Turbocharged L65 (VIN "F") engine. The L56 is emissions controlled with EGR and catalytic converters. The L65 engine has no EGR, and has no catalytic converter. There is a soot trap on L65 engines that is often mistaken for a catalytic converter. The L49 (VIN "P") and L57 are both naturally aspirated engines. L57 is listed as HO or Heavy Duty. Additional RPO codes are LQM (175HP) and LQN (190HP). Changes were made by GM to the 6.5 in their light trucks for emissions or reliability improvement. The 1992-1993 model years used a 6.5-specific Stanadyne DB-2 mechanical injection pump. GM replaced the DB-2 with the electronic throttle DS-4 in 1994-2000 vehicles. In mid-1996 GM implemented a redesigned engine cooling system incorporating twin non bypass-blocking thermostats and a 130 GPM water pump. This improved the flow through the block by 70-75% and flow to the radiator 7%. Applications 1994 - 1999 Chevy Blazer/ 2-door Tahoe / GMC Yukon/Chevy K-2500,K-3500 1992 - 1999 Chevrolet Suburban / GMC Suburban 1992 - 1999 Chevrolet and GMC C/K 2000 Chevrolet and GMC C/K 2500 & 3500 2001 Chevrolet and GMC C/K 3500 1994 - 2004 AM General Hummer H1 1994–present AM General HMMWV Specifications Engine RPO Codes: L49, L56, L57, L65, LQM, and LQN. Displacement: 6.5L / 397 cu in Bore x Stroke: 4.06 x 3.82 (in.) Block / Head: Cast iron / Cast iron Aspiration: Turbocharged (Borg-Warner GM-X series) Also available naturally aspirated. Valvetrain: OHV 2-V Compression: GM Early 21.3:1, GM Late 20.3:1, AMG/GEP Marine 18:1 Injection: Indirect Power / Torque (lowest): 180 hp (134 kW) @ 3,400 rpm / 360 lb·ft (488 N·m) @ 1,700 rpm Power / Torque (highest): 215 hp (160 kW) @ 3,200 rpm / 440 lb·ft (597 N·m) @ 1,800 rpm Max RPMs: 3,400 Fuel system The fuel system is a very simple design. A mechanical or electric fuel lift pump feeds a Stanadyne Rotary Distributor Injection pump at low pressure. The distributor injection pump controls both timing, via an internal centrifugal governor, and high pressure fuel delivery to the fuel injectors via internal precision hydraulic pumps. Near the top of the compression stroke fuel is atomized at high pressure into a hemispherical Inconel prechamber in the cylinder heads using Bosch pintle and seat mechanical fuel injectors. This is called Indirect injection. GM used fully mechanical DB2 series injection pumps on all military HMMWVs and 1982-1993 6.2's and 6.5's. From 1994 till end of production GM used the electronically controlled Stanadyne DS4 series of injection pumps in their light trucks. A mechanical DB4 series injection pump can be found on some 6.5L marine engines. Common Problems Main Bearing Web Crack: In both 6.2L and 6.5L engines this is reportedly fixed with a combination of improved higher nickel cast iron alloy and lower block re-design including, but not limited to, a main bearing girdle. These features are in the new for 2007 AM General GEP P400 6500 Optimizer enhanced 6.5L diesel presently being sold to the US Government for the 6 ton armored HMMWV. Crank Failure: Related to age failures of the harmonic balancer, the vibration damped accessory drive pulley, or the dual mass flywheel. Pump Mounted Driver: Relates to thermal failures. The PMD is screwed to the DS-4 injection pump on the 1994-2001 GM 6.5 diesel utilizing fuel flow to dissipate heat. The injection pump is mounted in the intake valley (a high heat area). The PMD contains two power transistors that should be cooled by proper contact with the injection pump body. If the pump is not precisely machined to make complete contact with the transistors via the silicone thermal gasket and paste, the PMD is improperly installed without the gasket or paste, the PMD is installed off center with the pump body, or corrosion develops on the mounting surface the PMD will overheat. Several companies manufacture an extension harness and heat-sink kits. These allow an owner or their mechanic to relocate the PMD away from the injection pump to a lower heat environment and/or a place that can get more air flow. Cylinder Head Cracking: higher mileage 6.5 engines exhibit stress related fractures in the cylinder head bowl. Stronger cylinder heads remedy this problem. Now that the History is out of the way on to the Upgrades for durability PMD Relocation Here is the How to i created not long after i joined this forum but i will also include the info of the whys and hows here. PMD Relocation To start with the process of relocation and the pros/cons of each method. 1st method: Intake mounted heat sink Initially when this weak point was discovered the aftermarket responded with various kits to move it from the pump to a heat sink bolted to the intake. Pros: Moves the pmd to a slightly cooler area Cons: Still inside the hot engine bay 2nd method: relocation to inside air box with a heat sink or fan. Some owners have moved this lil black box to inside their flat panel style air cleaner housings with either a computer fan and/or a heat sink. Pros: This works marganally better then method 1 in that it adds the air flow from the incoming air headed to the filter. As well as adding shielding. Cons: Same as method 1 3rd Method relocation outside of the bay to either the rad support or bumper. This is the method I will be explaining in this thread. Like the original 2 methods it adds a heat sink plus moves the box into cooler air, however this is much much cooler air, It takes advantage of the cooling ducts in the Diesel bumper plus uses the bumper as a heat sink itself. Pros: Finally moves the pmd out of the hot engine bay Much better cooling then the airbox method Takes advantage of another design feature of the diesel trucks. Cons: Possible exposure to moisture, Not a major risk as long as the seals on the weatherpak connectors are still good. and if you are going into deep water deep enough to affect it in this placement you prob should have it well siliconed or in the cab, Now onto the pics and how to: This is the pmd it arrived preinstalled on the heat sink, there would be a coiled harness here as well but by the time I took this pic I already had it installed on the truck. To begin with you remove the right side signal light and you will see a hole in the rad support for the ac lines, thread the harness through this hole as you can see this has already been done. Then you route the harness to a point it can be plugged into the original pmd plug once again already done. Note: routing will vary depending on if you are redoing a previous relocation or not. In this case the truck used had the air box method done so I had about a foot of extra wire to deal with. Then route the other end through the cooling hole in the bumper long enough to plug in the new pmd then feed the entire unit through the hole and bolt it to the bumper using one of the license plate mount holes, depending on if you have the mount still or not you may need to use washers. Reinstall the signal light and you are done, Enjoy having to not worry about having to access the pmd on a hot engine again and ease of replacement should the new unit ever fail. A brief explaination as to why to relocate the pmd/fsd Kinda. It controls the Drive By Wire throttle in the truck. Basically if it over heats..no throttle, no fueling really. PMD stands for Pump Mounted Driver. Since when these trucks first came out all the way till the Dmax replaced the Detroit 6.5 The lil black box has been bolted directly to the Injector pump which is right in the center of the V of the engine. Roughly where your thermostat housing would be on a gas small block engine. But it was prone to overheating thus the problems mentioned above. The proper fix is to mount it on a heat sink and relocate it out of the engine bay. Which is what i will be doing once my new PMD and relocation kit arrive. Mounted in this configuration it is refered to as a Fuel Solenoid Driver or FSD for short.