Mercedes conversion

79-85 Mercedes

Mercedes Conversion

One of the easiest 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 numerious 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 witht he helpful books and videos out ther.

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 – Purchase here

Flat Pate Heat Exchanger 20 Plate Braized FPHE – Purchase here

Heated Filter – Purchase here

Tank – Bought a used boat tank Ebay

Hose and Fittings –– Purchase here

Conversion Schematic

Fuel

Item	Part Number	Description	Source	Qty	Cost Each	Ex Cost
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

Item	Part Number	Description	Source	Qty	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

Item	Part Number	Description	Source	Qty	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

Coolant Splicing

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!

Here’s a map of the flow.

Return Valve routing

Fuel Line Routing

View from under trunk. Hole drilled in trun floor and extra hose wrapped around fuel lines and sender wiring to protect

Electrical

Priming

I primed the line from the tank and the filter with this oil pump bought at an auto parts store.

Other Components

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.

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.

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.