I bought this Suburban back in late spring of 2006 as a project vehicle. Oh, there were several things on it in need of rehab, but that's not the project I'm referring to... I had met some 'fool' (or so I might have thought at one time...) running used vegetable oil as fuel, and I wanted to see if I could do it too.
Well, it wasn't as casual as all that.  I spent many months researching the idea to see if it was as plausible as the person I met represented it to be. What I found impressed me. From what I learned, converting a Diesel vehicle to run on veggie might be a reasonably responsible thing to do, if one were willing to educate himself enough to do it right.
We had previously enjoyed owning a 35-foot motorhome. With three young girls at home, this made for many wonderful family experiences and memories together. Alas, when the price of fuel went to the moon, the coach found a new permanent home -- in the driveway beside our house! But impressing the neighbors with a trophy wasn't why we'd bought it. Something had to change. But with $3+/gal gas and 5mpg fuel economy, the future didn't look bright for the motorhome.
So, I thought that if I could successfully convert a Suburban to run on veggie oil, we could have a daily-driver family vehicle (which is now saving us over $400/mo in fuel expenses) and could pull double-duty as a tow vehicle for a travel trailer. This way, perhaps we could start enjoying our family camping experiences together again!
After about nine months of research, I found this 'Burban, and decided to take the plunge. I also immediately found several items in urgent need of maintenance. First of all, both the outside and inside door handles on the driver's door needed replacing. The tires were all shot. All steering linkage had done its time and was due for parole. The PMD failed the second day we owned it. About two weeks later, the odometer died... After resolving these issues, I began to acquire the parts necessary to tackle the conversion project.
In August of 06, I finally got to turn the key on the conversion. It worked surprisingly well. There were a few minor tweaks to do, but all in all I consider the project an extremely satisfying success. As of this writing (Sept 07), I have nearly 30k on veggie oil, and am happier than ever with my results.
Next spring, we hope to finally acquire that travel trailer and achieve the ultimate objective of the whole idea. Can't wait!! 
Here's an overview of what I've done, and how the veggie circuit runs:
I decided to use that wonderful 42-gal stock fuel tank for my primary fuel -- veggie oil. So I bought a brand new tank for Diesel that is mounted inside the chassis rail beneath the driver's seat running back under the second row seats. Convenient space for it, and the running boards do a terrific job of hiding it. Unless you get on your hands and knees, you can't see the tank from the street. And there is better ground-clearance for it than for the rear axle.
The tank I chose was a stock saddle tank for a mid-80s Chevy pickup -- yes, the Dateline tank!  It was the right size and is DOT approved, etc., with an eye toward liability issues in the event of an accident. (Of course, Dateline's issue with it wasn't the inherent safety of the tank itself, but rather, the way it was mounted allegedly made it vulnerable.) Delightfully, the stock fuel lines have a built-in break right next to where this tank is mounted, making connecting this tank to the original Diesel fuel circuit a cinch!!
The veggie circuit runs like this: Mounted into the stock 42-gal tank (from the top, near the center) is an Arctic Fox coolant-heated fuel pick-up -- like is often used in big-rig Diesels in cold climates. This begins heating the veggie oil (heat being a must for proper injection properties, due to the vastly different viscosity of Diesel vs. veggie oil at ambient temps), and melts a pool of oil in the tank to provide a continuous supply, should the ambient temps get cold enough to solidify the oil -- only an occasional likelihood here in NC.
From there, it runs to a 16-plate flat-plate heat exchanger where hot coolant tapped from the 'Burban's rear heater system warms the oil significantly. Next item in line is the VorMax dual-stage fuel filter, which is also coolant-heated (head only).
From there, the fuel line runs up toward the engine bay, bundled with the coolant lines for the rear heater system, to collect a little more heat. Half-way up the right-hand chassis rail, I've installed a second stock-style lift pump dedicated to veggie (mirroring the original stock lift-pump for Diesel, which is mounted on the opposite chassis rail).
Entering the engine bay, the fuel meets a second 16-plate flat-plate heat exchanger, and then a 32-amp electric heater. (I only use this when the weather is cool, and when I first switch over to veggie, to speed bringing the oil up to proper temps.)
Passing along through a Pollak 6-port motor-driven valve which switches between veggie and Diesel, and also selects which fuel-level sending unit's reading to forward to the fuel gauge on the dash, fuel then passes through a temp gauge probe. From the probe, the oil travels a short distance directly to the IP.
Running on veggie, the fuel return is looped back through the heat exchanger to capture more heat (it runs 160* into the IP -- and since the PMD has been relocated to the front bumper à la Heath, there have been no problems from the higher than ordinary fuel temps). This also maximizes filter life, which has been around 10k miles typically, so far.
The dash switch that selects between Diesel and oil activates a relay, which in turn activates the Pollak valve. Downstream from this relay, I needed another relay to select which lift-pump to divert power to. I didn't want either pump powered when it was not in use. I also wanted the new lift pump to remain behind the factory engineered safety devices, such as the OPS and other relays/fuses. That relay was a hunt!! I finally found that a relay for the air conditioning system on a 1978 Olds works perfectly for this application! 
The second switch on the dash controls the electric heat to the oil, and is also wired in behind the primary relay for the veggie circuit. This way, it automatically shuts down the electric oil heater when I switch back to Diesel if I have left it in the "On" position. This switch is lighted, which reminds me that the electric heat is on (which I may not need on once the oil is warmed up when ambient temps are warm enough), AND shows me there is power being sent to the lift pump (which could be a helpful diagnostic tool should the OPS ever crap out).
The veggie oil temp gauge is helpful as I want the oil to be at least 160* at the injectors. (I can probably get away with 140* at the probe (though it almost always runs right at 160*) as the oil would almost certainly pick up at least an extra 20* from the IP and the injectors.) I also don't want the oil passing through the Pollak valve to rise above 185*; that being the highest certified operating temp of that valve. (I also probably don't want any above that for the sake of the IP.)
So, after a couple years, and around 40k miles, I am very happy with what I've done. Might the conversion end up shortening the life of some of my components? Perhaps. But when I'm saving more than four C-notes a month in fuel costs, I'll accept that if it occurs on a non-catastrophic scale!  (And I'm taking all the reasonable steps I'm aware of to ensure avoiding that kind...) Like if, say a 100k mile part only lasts 80k, I'd say it's a reasonable compromise with the fuel savings. Time will tell...
Can't wait to start hauling a trailer with it!!
Drizzle
Later -- 9/11/08...
Well, I guess the trailer will get put off for a while. The money I'd been planning to spend on that is/will be getting poured into another alternative fuel project. See it here: http://www.evalbum.com/1791
|
|
|
