1995 Chevy K2500 - Heath Diesel Extra Heavy Duty Cooling System - 6.5L Upgrades

To replace the water pump, Hughbanks removed the front timing cover, cleaned it with a wire wheel, and sealed the new Heath Diesel pump to it with the supplied gasket set.

The new 21-inch fan was key to moving more air through the factory radiator. Compared with the original (right), the new composite nine-blade fan will move a ton of air. You'll also notice that dirt had begun sticking to the fan clutch on the original fan. This suggests that its hydraulic fluid was starting to seep out and that our stock cooling fan's days were numbered.

Hughbanks tested the clearance around the new 21-inch fan and found that on our application it rubbed the stock fan shroud. A little work with a sanding wheel on a die grinder got us the necessary clearance. Hughbanks then replaced the factory thermostat with the new version that Heath Diesel sent us and cleaned the bugs, leaves, and dirt out from both sides of the radiator and coolers. Cleaning out the crud was critical.

Heath Diesel told us the factory maintenance schedule for the crankcase depression regulator (CDR) valve is every 60,000 miles, but in the company's experience, the valve can get gummed up in as little as 30,000 miles. Ours looked pretty crummy, so Hughbanks replaced it.

Another maintenance item that Heath Diesel recommended was this electronic filter harness that's located under the injection pump. This short length of wire is prone to heat damage and can cause poor engine operation.

To feed the Stanadyne injection pump a consistent fuel supply, Hughbanks crawled under our Chevy and replaced the factory lift pump with this new version. The original lift pump appeared to have been replaced because it was missing the GM Weather Pack connector, otherwise this upgrade would have been a bolt-in. Back on top of the engine, Hughbanks screwed in the new heavy-duty oil-pressure switch that controls the new pump.

Perhaps the most common 6.5L turbodiesel problem area is the factory pump-mounted driver (PMD) on the electronically controlled DS4 injection-pump engines. The PMD sits in the injection pump, and its circuitry is cooled by the diesel fuel passing through it. Some say the tight packaging of the injection pump in the lifter valley heat-soaks the PMD to the point that the fuel cooling is not enough. Heath Diesel offers two kits that remotely mount the PMD away from the engine heat. We incorrectly ordered the two-wheel-drive version (PN HDP1296) for our 4x4 truck (we should've ordered PN HDP1280), but either version will work. The main difference is the mounting location.