Heath Diesel’s 6.5L Diesel Heavy-Duty Cooling System Upgrade

Volume 2 Issue 2 - Diesel Articles

6.5L diesel cooling system temperature gauge

The GM 6.5 L diesel truck has a reputation of overheating when towing or hauling heavy and uphill. Those models built prior to 1997 were supplied with a cooling system that, even under the best of circumstances, provided only a marginal performance. Most of these vehicles were not able to maintain coolant temperature at or below the maximum – in my book – allowable 210°F. The normal accumulation of bugs, dirt and crud in the radiator and A/C core made a bad situation worse. Beginning with the ’97 models, GM increased the water pump flow, added a dual thermostat setup and a slightly improved fan clutch in an effort to make things better. These improvements affected a bit of an improvement.

Through years of experience with the 6.5 L diesel, working it hard under towing conditions, Heath Diesel has determined some important and effective remedies for the cooling inadequacies that plague these trucks.

Heath Diesel had long known that retrofitting the ’97 high-output water pump with the dual thermostat onto older models did not provide a meaningful improvement in temperature control and, while we found ways to improve the cooling system performance, the system as a whole did not deliver good and reliable temperature control under tougher towing conditions.


Volume 2 Issue 2 - Diesel Articles

efilive-diesel-tuning-injection-quantity-flowchart-featureWhile typical module and program-type boxes allow the user to select something like "Stage 5/150 HP", once you have selected this setting, the module makes all the decisions for you.

In contrast, EFILive’s custom diesel tuning software, on the other hand, allows the user to do something like:

  • Ramp in 70% more fuel
  • Eight pounds of boost
  • 12 degrees of timing in range from 2,800 to 3,500 RPM.

Volume 2 Issue 2 - Diesel Articles

Diesel timing tool EFILive Flashscan V2Just about everything you always wanted to know about the variables that affect the timing of your diesel engine; including the relationship between diesel timing and fuel economy.


Das Kommandofahrzeug (6.5L Diesel Suburban Command Vehicle)

Volume 2 Issue 2 - Diesel Articles

She hated it... of course she would... It is a real man’s truck: huge, ugly and loud – naturally, it was love at first site for me. I bought it from friends we consider family in Columbus, Ohio. They purchased it brand new on November 24th, 1993 at a downtown dealership for $26,934.72. I knew the truck had a 100% vehicle history, had never-ever been smoked in and if there was any question ever, about anything, it was a phone call away.

The only diesel vehicle I owned before was a VW Lupo 1.4 liter TurboDiesel – the only vehicle that it made any sense to own when you lived in a place like downtown Munich.

Now I live in a metropolis often referred to as Motor City, USA and while a VW Lupo 1.4TD may be hilariously fun, cool and economical; it has no place here. This city with its UAW-dominated parking lots south of the notorious Eight Mile demanded a bullet proof urban assault vehicle that smirks at the potholes big enough to swallow the little Lupo. The Suburban may lack the aramid-kevlar enforced sheet metal and true bullet proof glass of a real urban tank but it makes up for it with a stealth factor that blends into the Detroit surroundings perfectly. So when the owners decided to replace it with a Duramax-equipped Kodiak, I immediately stepped in and gladly adopted the Suburban as my own.

\Nick Buckners 6.5 L Diesel Suburban Das Kommandofahrzeug Nick Buckners 6.5 L Diesel Suburban Das Kommandofahrzeug Nick Buckners 6.5 L Diesel Suburban Das Kommandofahrzeug
Nick Buckners 6.5 L Diesel Suburban Das Kommandofahrzeug Nick Buckners 6.5 L Diesel Suburban Das Kommandofahrzeug Nick Buckner works on his VW Lupo 1.4TD
(Click on any image to enlarge. Suburban photos by Anthony Cressey)



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