Sensitive Fuel

I installed the vacuum sensor right to the output side of the fuel selecting solenoid. Whether you are running diesel or veg this sensor with tell you how hard the lift pump is sucking to pull the fuel through the filter, and if its sucking too hard, you know you need a new filter.

I also installed a fuel temp sensor on the return line. This will tell the temp of both the diesel and veg as well. By having it on the return line I get a sample of fuel that went along the same path as the fuel that was sprayed into the engine, but took a different path in life. I've seen some located where I put the vacuum sensor, but after the oil hits all those metal components of the engine it is bound to have its temp affected. Before you switch to veg, it will be reading the temp of the diesel which will show how warmed up the engine is and if you are ready to switch.


The Injector Line Heaters!

I first cut 6 5" pieces of the Teflon Tubing and then one-by-one crimped on a butt connector, clipped the 316 SS wire to length, and installed the closing connector.

Then I held the heaters up to the lines to figure out the length of each lead and chained all the heaters together in series and wrapped silicon tape around the exposed metal connectors.

I wrapped some Teflon tape around the injector lines and then, using silicon tape to hold it down, wrapped the heaters on the lines.

Then I put on two layers of silicon tape and the shiny/fiberglass insulating tape.

On top of all that I zip-tied on some pipe insulating foam. IT WORKS! draws around 8 amps, about 100 watts of heating power.


Edits, thanks Reggie, I'm going with your idea here. I'm going to go use SS wire instead of the cupron, I put on the cupron and found that it is so thin that it is hard to work with and easily burns itself out.

Here are the McMaster items for the new line heaters:

Type 316 Stainless Steel Wire .032" Diameter, 1/4-lb Coil, 91 ft/Coil

HI-Temp Chemical-Resistant PTFE Sleeving .034" ID, for 20 Awg Wire

High-Temperature Crimp-on Butt Splice Noninsulated, 22-18 Awg, 900 Degree F Temp Rating, Packs of 100

392 Degree F Chemical Resistant Wire 18 Awg, .068" OD, 600 VAC, Red

When these parts come in I'll rewrap the inj lines with teflon 3 mil tape, wrap the ss teflon coated wire around the inj lines, install the high temp wiring componenets, cover the heaters with silicone tape and a final layer of thermal exhaust manifold tape I bought from AutoZone.

So frustrating, I would be done under the hood and finishing up the rest this weekend if the cupron had worked like the guy who sold me it said it would. It took hours and hours of now unbillable time... How much longer now till it's all done? Not much... If I had known how long this part would take I would have just ordered the heater line from FattyWagons like I have before.

Another Edit... by request of the owner and for aesthetic reasons the filler to the veg tank is going to be placed on the same side, and just ahead of the diesel tank filler.

Edit to a Side Note: A Mercedes diesel expert came to look at the conversion and said that the design of the sd 33 is only loosely based on the diesels MB put into the W123 chassis.

Tank Paint Edit: Instead of the Industrial enamel paint that I mentioned for the tank, I ordered special tank liner and exterior sealer paint from Summit.

I've done a conversion in 3 days, starting with nothing, drinking redbull and rush ordering parts. You go into stores, see what they have, and make it work. Decisions are based on what's available more than anything else. It works, but with a rare and cool vehicle like this, I can't just put in the parts that get the job done or it will stick out like a sore thumb...


Prep for Prep

Here is the engine compartment with everything ready to accept the lines coming from the new veggie tank. An electrical whiz buddy of mine is going to come in a make all the wiring "nicey nicey." The Cyberdyne gauges were back ordered all over the place so after combining 3 vendors, they are now on their way. Notice the greasecar brand solenoid switches and the nest of hoses that are new from the last engine compartment photo. To connect the pex tubing I'm using those new shark bite push on fittings, the guy at Home Cheapo swears by them...



The compression fittings have to be drilled out with a 3/8 drill to allow the 3/8 OD aluminum fuel line to pass through. The one with my grubby fingers on it still has its stock brass stop inside and the other one has been drilled out.

A 3/4 inch barb can be threaded with a 1/2 fpt die. I loaded it with Teflon tape and cranked the the compression fitting home.

The whole idea with doing it this way (instead of getting a FPT tee and screwing all the fittings in) is you save a lot of space in the tight spots where these are going and you save a lot of dough.


Injector Line Heater

Here we have silicone tape sandwiching some welding wire. 8ft of this wire gave me about 1.2 Ohms of resistance which comes out to around 10 amps of heating power. It actually worked pretty well, and the tape didn't melt or misbehave, but when it came time to install the heater on the injection lines it was too stiff. So next I used 30ga heavy thermaleze / cotton cover insulated cupron which wrapped around the injector lines very nicely over a layer of silicone. I will pick up some high heat wire connectors and wrap silicone around the top. This wire is 2.94 Ohms per ft so the wiring will be done in parallel connecting 6, 2 amp, individual heaters creating a 12amp heating system. Thank you Mun and Tyler for helping me pass electromagnetism.


Custom Fit

The 7/8 14 UNF fittings for the gargantuan Racor Filter were unavailable from the Sprawl Mall from Stonington to New London, and most places barely new what I was talking about. I ended up unscrewing the 1/2" Push-on fittings, cutting of the barbs, and tapping my own holes to screw in the 3/8 barbs needed. I put 2 giant hose clamps around the Pex tubing on the top and bottom of the wrap, screwed the new fittings in, bolted the filter in place, and coated the whole thing with thick shiny foam insulating tape to lock in the heat. I had the same luck in finding a flange to barb fitting locally (for the diesel-out on top of the filter) so I made one out of a piece of copper tubing. It's that long piece sticking out of the diesel filter that will be trimmed the next time I look at it in person.