Tuesday, September 15, 2009

Das Kommandofahrzeug (6.5L Diesel Suburban Command Vehicle)

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.

Since then I have been driving it almost daily. My friends will tell you that I lovingly refer to it as Das Kommandofahrzeug – “Command Vehicle” in English– which I found to be the perfect nickname for this project – and it also suits my driving style.
Other than having everything from the original window sticker, all the service records, repair orders, parts receipts and fuel stops, I initially knew nothing about the truck or the 6.5 liter turbo diesel engine. Granted, over the years I had ridden in the truck many times and even helped the previous owner, a long time friend, with previous modifications, but I never stopped to think that it would one day be mine. I did know that 6.5TD Suburban’s are sought after and rare. I understood many folks search high and low before they find one in good shape. I guess I had the luck of one finding me.
Only later did I find out how lucky I was after decoding the VIN and RPO codes and reading up on the legends and myths of the 6.5. The fifth and sixth letter denote the preferable two wheel drive and three-quarter ton designation; but the most important letter, for me, is the eighth. This letter gives you the engine type and make – in my case the letter F:
  • 8 CYL, 6.5L, TURBO, HO 
  • 4.10 RATIO 
A truck with these options is not easy to find: they present an excellent starting point for a daily driver and weekend tow vehicle.
I took ownership of the truck with approximately 160,000 miles and with only one major (warranty) repair at 92,448 miles at the dealer in March 2001 – the well-known Diesel Injection Pump replacement. Of course my engine has also suffered from the well documented and known poor placement of the PMD on top of the engine. In my case, after replacement of the entire Injection Pump the symptoms returned. The issue was fixed with an FSD cooler mounted not far from the original location but on an aluminum-finned cooler on top of the air intake plenum. I can only advise others who come across this solution to realize how short sighted it is: it places the PMD in the center of the heat buildup during shut off. It will only survive for a certain number of heat cycles. As a result of this “fix” I experienced the only time that the truck left me stranded. Not long after, I replaced the unit with a PMD Isolator from Aside from this, I have discovered no other preventative maintenance or modifications mistakes performed by the previous owner.
The truck also came with some other must haves already installed:
  • Three gauge A-pillar pods 
  • Dual thermostats; and, 
  • Aluminum transmission pan. 
  • It also had a nice Kenwood stereo system. 

A 6.5 Diesel that was "Born to Run"

Born and raised on the German back roads and the Autobahn, I also had to ensure at least some degree of road handling and cornering ability. I installed a set of Bilstein HD shocks the same weekend I picked up the truck in Columbus. With the independent suspension of the two-wheel-drive version up front, the truck handles quite nicely with this upgrade.
I drove the truck without major temptation of changing anything else until the PMD on the FSD cooler failed. Since I knew that the previous owner investigated the issue just as in depth as I would have, I tried replacing the oil pressure sensor and the fuel lift pump. Finally, working with Heath, we pinpointed the PMD issue and I replaced the troublesome part.
In the course of troubleshooting the PMD issue, I discovered the vast 6.5 knowledge of Bill Heath and his crew. I realized that there was more to my 6.5 than meets the eye. To sum it up, my Suburban could have been the subject of maxxTORQUE’s Winter 2007 Suburban Renewal. Starting before that story ever came out, I have installed heath upgrades:
  • Heavy duty lift pump – (in conjunction with OPS a must in preventative maintenance) 
  • Electronic Filter Harness 
  • PMD Isolator 
  • TurboMaster Boost Controller 
  • Max-e-tork PROM (first the HP4 now the GLE) 
Ever since the day I installed the PMD Isolator the truck has never left me stranded. It has also put a grin on my face every time I started it up and driven it, thanks mostly to the TurboMaster and Max-e-Tork PROM.
6.5 L Diesel Road Trip
Combine the recent developments in the Automotive Industry which I call my work home, and the mid-life crisis that seems to hit every man at some point, I have re-evaluated my priorities and quit my job.
Instead, I have been planning a road trip through the US with what I believe to be the culmination of American Engineering – my beloved 6.5TD Suburban.
Accompanied by my Bavarian beauty who left her hometown to follow me to the land of opportunity, stopping at every worthwhile site along the way, traveling from Detroit to FL, west to LA along the Grand
Nick's Planned Route for his 6.5L Diesel Suburban "Das Kommandofahrzeug"
Canyon then North to Heath Diesel to visit Bill, the Obi-Wan Kenobi of 6.5TDs to pay my respect and thank him for all the parts that made my Suburban so much better and reliable. Thanks, Bill, for the inspiration to finally quit my job and go out on my own.
Bill Heath was also responsible for putting me in touch with some other great names in the 6.5 world, namely turbine doc, who is the 6.5 lead moderator at After hearing about my out-of-the-ordinary plans, He conferred with the owner, moderators and the tech guys at DTR and they have offered to sponsor a sort of travel blog of our trip. They will ensure that we have the whole crew of 6.5 experts as a long distance pit crew. If we get lucky, maybe we will get some BBQ invitations along the way for a chance to meet and greet other 6.5 enthusiasts. I would like to say that I have only on rarest occasions, no matter what part of the globe or what brand of vehicle we are talking about, been part of such an open-minded, friendly, helpful and cool community of people as the 6.5ers on DTR. Allow me also to mention slim shady who is a driving force in keeping the innovation process alive with his efforts of introducing a modern turbo design for the 6.5, the A Team Turbo. He was also nice enough to sacrifice a whole Sunday to help me get the Suburban on the lift of his heated garage and assist with some final tweaks before I headed out.
The truck is finally ready from the mechanical side, since I got around to the three last project installs that were laying around in my garage ready to be put on:
  • Hi-Flow Crossover 
  • Super-Flow Four Inch Exhaust System 
  • Set of Injectors and BOSCH Duraterm glow plugs 
Since all my modifications have been already described in depth in maxxTORQUE’s Winter 2008 Suburban Renewal and are pretty much a standard and a must for the 6.5 owner, I want to use the opportunity afforded by my road trip to evaluate all the modifications and give a sort of bang-for-the-buck buying guide backed by some more photographs.
It also happened, that while these modifications made it necessary to remove my existing GM4 turbo, a freshly rebuilt and ported GM8 turbo was available. We transplanted it into my rig without much effort other than having to replace my TurboMaster with the version designed for the GM8 turbo used in 1996 and after.

6.5 Diesel Parts Buying Guide

The following buying guide follows my personal priorities; yours may vary depending on your preference. My priorities are as follows:
  1. Reliability, Dependability and Longevity 
  2. Efficiency 
  3. Bang-for-the-Buck in terms of go fast performance 
  4. Ease of installation 
Based on these priorities, the following Heath Diesel products list represents what I feel the vehicle needs in order to make the 6.5 a reliable and powerful daily driver and weekend towing machine:
  • PMD Isolator 
  • Heavy Duty Lift Pump, OPS, Electronic Filter Harness 
  • TurboMaster boost controller and Max-e-tork GLE / GL4 PROM
  • Hi-Flow Crossover, downpipe and Super-Flow Exhaust 
  • BOSCH Injectors and glow plugs 
Up until recently, I did not know that another part – due to poor design – needs to be replaced as badly as the PMD. When we removed the factory down pipe from the 6.5 my first thought was that I should have not waited so long.
This makes the restrictions in the rest of the factory exhaust system not even worthy of mentioning. After the upgrade, when I heard that turbo whine, accentuated by the sweetest exhaust note I have ever heard from a 6.5, I knew this upgrade should have also been done a long time ago.
And even if the Bavarian beauty, waiting for me long into the night the day of that wrenching session, was disrupted by the sound only a man can appreciate, she will admit: She does not hate Das Kommandofahrzeug quite as much as she used to.

Thanks and Invites

Other than the people I have already mentioned, I want to thank:
My friends and family for all their support
(Mom, Dad, Andy, Ben and everyone at home)
Sir Wallace Richardson, who investigated the purchase and all the options in 1993
Mrs. Mary Richardson for writing the check after Sir Wallace picked it out ;-)
Chip Richardson for taking care of the truck before I adopted it !
Bill Heath for making sure I continue to take good care of it, engineering and supplying the necessary parts and for helping me in so many ways!
Of course my lovely wife for letting me buy the huge, loud and ugly thing ;-), and
Manfred Bayer who in life and after has inspired me to do the right thing – may he rest in peace.

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