Contents
Mercedes Conversion
One of the simplest and best cars to convert is a classic late 70s/early 80s Mercedes Diesel. Costing over $40,000 new back in the 80s, these cars were overbuilt having numerous backup systems for when the main parts fail.
They are also tolerant of the rigors of running vegetable oil due to their robust lift and injection pumps and well built engines. People have successfully run SVO in these cars with no modifications.
More common and dependable are dual tank systems that come in a variety of configurations. Many of these cars suffer from abuse and neglect, yet keep on running.
To fully restore such a relic would cost a fortune, but catching up on basic maintenance is not so challenging. Many of the maintenance items are easy enough for the novice, especially with the helpful books and videos out there.
Pre-conversion maintenance items:
- New Thermostat
- New air filter
- Fuel filter
- Valve Adjustment
Also, it would be wise to check the compression to gauge engine health before forging ahead with a conversion. An unhealthy engine is not going to like WVO.
Major Conversion Component Sourcing
Valves
3 Port Solenoid Valves
Flat Pate Heat Exchanger
20 Plate Braized FPHE
Heated Filter
Bought used from Forum Classified Ads
Tank
Bought a used boat tank from Ebay
Conversion Schematic
Fuel |
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| Item | Part Number | Description | Source | Quantity | Cost Each | Ex Cost |
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| 1 | * | Heated Filter with Water Block | WVO Designs | 1 | 150 | 150 |
| 2 | * | Flat Plate Heat Exchanger | WVO Designs | 1 | 60 | 60 |
| 3 | * | 3-Port Valves | WVO Designs | 2 | $47 | $94 |
| 4 | 2191A | Fuel Tank – 19 gal tank | Summit Racing | 1 | 262.95 | 262.95 |
| 4.5 | * | Raw Power Hot Stick | WVO Designs | 1 | $150.00 | $150.00 |
| 5 | 5/16″ Fuel line | WVO Designs | 30 | $2.50 | $75 | |
| 6 | Injection Hose Clamps | WVO Designs | 12 | 1 | 1 | |
| 7 | n/a | #6 JIC to 1/2 NPT fitting | WVO Designs | 12 | 3.95 | 47.40 |
| 8 | * | Straight Swivel Fittings – Hose Barb | WVO Designs | 8 | 3.95 | 63.20 |
| 9 | * | 90 Degree Swivel Fittings – Hose Barb | WVO Designs | 4 | 8.95 | 35.80 |
| 10 | AC-Banjo Bolt | Solid Banjo Bolt for Fuel Return | Greasecar | 1 | $5.00 | $5.00 |
| 11 | n/a | Mounting Bracket for Valves, FPHE | * | 3 | $ | $ |
| 12 | * | Self Tapping Screws | * | 6 | $ | $ |
| * | * | * | * | * | * | $Total |
Coolant/Heating |
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| Item | Part Number | Description | Source | Quantity | Cost Each | Ex Cost |
| 1 | * | 5/8″ Heater Hose | Auto Parts Store(Carquest) | 50 | $1.00 | $50 |
| 2 | n/a | 3/4-3/4-5/8 Coolant T’s | Greasecar | 2 | $5.00 | $5.00 |
| 3 | * | Hose Hangers/Brackets | MSC Direct, Greasecar, Hardware Store | 3 | $ | $ |
| 4 | * | Hose Wrap/Protectant | * | * | * | * |
| 5 | * | Hose Clamps | * | 12 | * | $ |
| 6 | * | * | 2 | $4 | $8 | |
| 7 | * | 1/2″MPT to 5/8″ Hose Barbs | WVO Designs | 6 | $4.95 | $29.70 |
| 8 | * | Rubber Grommet for Lines through Trunk | MSC Direct | 1 | $ | $ |
| 9 | * | Fat 1 1/2ft zip ties | Hardware STore | 10 | * | $ |
| 10 | * | Self Tapping Screws | * | 5 | $ | $ |
| * | * | * | * | * | * | $Total |
Electrical |
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| Item | Part Number | Description | Source | Quantity | Cost Each | Ex Cost |
| 1 | * | 3 Position Rocker Switch | 1 | $ | $ | |
| 2 | n/a | Fuel Level Gauge(Must have same Ohms as sender) | 1 | $ | $ | |
| 3 | * | Switch and Gauge Plate | Greasecar | 1 | $5 | $5 |
| 4 | * | 16 guage yellow wire Wiring | Auto Parts Store | 5ft | * | * |
| 5 | * | 16 Gauge Blue Wire | Auto Parts Store | 5 ft | * | $ |
| 6 | * | 18 Gauge Green Wire | Auto Parts Store | 20 ft. | * | $ |
| 7 | * | 14 Gauge Black Wire | Auto Parts Store | 5 ft. | * | $ |
| 8 | * | 16 Gauge Terminal Rings | Auto Parts Store | 5 | * | $ |
| 9 | * | 14-16 Gauge Butt Splices | Auto Parts Store | 20 | * | $ |
| 10 | * | Spade Connector for tapping fuse power | Auto Parts Store | 1 | * | $ |
| 11 | * | Various other splicing/connectors for gauge & Switch | Auto Parts Store | * | * | $ |
| 12 | * | Bag of 1ft. zip ties | Hardware store | 1 | * | $ |
| * | * | * | * | * | * | $Total |
Tools Needed
- Wire Cutters and Crimpers
- Screwdrivers
- Cordless Drill
- Hole Saw bit
- Patience
Conversion Pics |
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Coolant Splicing |
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| Tapping the coolant lines. Coolant from the engine gets T'd next to the oil filter housing. | Coolant return below turbo, next to water pump. |
Engine |
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| Here's a map of the flow | |
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| Return Valve routing | |
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Fuel Line Routing |
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| View from under trunk. Hole drilled in trunk floor and extra hose wrapped around fuel lines and sender wiring to protect. | |
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Electrical
Priming
I primed the line from the tank and the filter with this oil pump bought at an auto parts store.
Other Components |
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| This is a 3 way rocker switch on/off/on bought from Seachoice. I found a replacement plate from pick and pull that was in better shape than my cracked wood molding. The switch fit perfectly where the fader dial used to live. A little glue and voila! I was hoping to find a switch that had the veggie markings already on it, but cannot find them anymore, thus the V for veggie. | |
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| Here's my 21 gallon marine tank. It's unheated. My return fuel heats the tank nicely(it gets hot on long drives). I also do not run hydrogenated or creamy oil and live in a mild climate, so I don't really need a heated tank. | |
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| Here's my 20 plate flat plate heat exchanger. I had to bury this down low beneath the headlight. There is a perfect spot for it to rest on. It is secured with a large zip tie. Yes, I replaced that hand twist hose clamp. | |
