I've converted the merc with a Greasecar system and am having a problem with air entering the system. I've put a clear section of tubing in the fuel line and it seems to becoming from the diesel return side. Has anyone had some experience with this system that could suggest where the air is likely to be coming from? I've tightened up all the clamps, cleaned up the diesel filter assembly, etc, still got a slow stream of tiny bubbles, every minute or so the line jerks and a big slug of air comes thru.

thanks.

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84 300 D Turbo, 222,000 and rolling, veggie most of the time.
91 350 SDL veggie wannabe

Go to the greasecar.com forum for answers to questions on the Greasecar system.

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'79 300SD
'82 Chevy Chevette diesel

I also had air entering my system as well. Where I found the leak was a bad metal washer on the fuel filter unit. Go back and check all of the connections/washers going in and out of fuel filter. Hope this helps!

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1985 300SD - 167k miles
1992 F350 7.3 (Soon to be converted to 2 tank Veggy/WMO)

Make sure the tank strainer is not clogged. If it is the fuel system will build up quite a bit of suction and draw air in from a lot of places. I don't know anything about the vegetable oil system you have but with a stock fuel system you can test this by disconnecting the rubber supply and return hoses in the engine compartment, insert them into a container of fuel, and run it that way to see how it works without the tank in the loop.

I'm installing my greasecar kit on my 87 300 sdl, and most of the installs I've done on MB. Tend to leak air on the stock fuel lines. Meaning when you cut into the plastic stock fuel lines and place your fuel lines on them make sure they are tight. And if you have to place a small amount of black silicone around the lines. This will allow for a clean tight seal.

The problem with a air leak is that you have to check all the lines, because unless your using clear lines, your going to have problems finding it.

One last chance to find the leak, is to remove one side of the line and place a vacuum pump to it, and see if you get any air when you draw on the line. If you do get bubbles you know it's somewhere down the line.

Good luck,

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Professional greasecar installer
Austin TX


98 Jetta TDI with grease car kit + veg-therm (totaled)
87 MB 300SDL running on B99 / greasecar kit + 30 fphe
www.austingreaseguys.com

The hose they send to connect to the banjo bolts is a little too big. After much frustration, I cut about 1 1/2 inches of the old clear fuel line, heated it a little a pushed it onto the banjos. The rubber fuel line then was put over the clear. This helped A LOT.

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Brad
1981 300TD - daily driver
1963 Chevy II
2001 F-250 7.3 Power Stroke

I bought the vac pump. It's great to have the right tool. I have removed/replaced the clear plastic lines with rubber lines that are sized better. tonite i tested the priming pump with the vac, didn't hold any vac at all so i replaced the pump. still have air coming thru the return side. I tested the IP with the vac pump, started at 15" and dropped to 12 and seemed to hold. when i started the car, got the same air problem, like I had done nothing!? are there seals inside the IP? or perhaps where the metal injector lines attach? I think the next thing I'll try is to get a handfull of the metal washers and replace them all on the whole system. One of these days......

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84 300 D Turbo, 222,000 and rolling, veggie most of the time.
91 350 SDL veggie wannabe

Replace all your rubber fuel lines with translucent polyurethane tubing. You can get it at www.mcmaster.com. Most of the sizes you will need is 5/16", but my '87 300D has 1/4" nozzles on the fuel filter, lift pump, and injection pump. You may have to mate those two sizes with an adapter. Get the tubing with 1/8" wall thickness. This way you will see any place air enters the system.

Greasecar has a design flaw in my opinion: They loop the return back to the supply so that any air that gets in the system has no way to get out. I solved this by plumbing in a "T" with a needle valve into the return line, The "t" goes to a return PEX line that I routed back to the veggie tank. This allows me to send a small amount of fuel and air back to the veggie tank, while still allowing most of the pre-heated fuel to go back to supply.

Good luck!

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1987 Mercedes 300D ~200K (Greasecar & Biodiesel)
1993 Ford F-250 7.3 IDI diesel 165K (Biodiesel)
1996 Thomas/International Bus with DT466 engine

.

Hello Everyone

I found a hard to find air leak by pressureizing the entire system
at the fuel filler neck.

I wrapped a rag around the air gun fitting on the air compressor hose,
and held it tight aginst the filler neck on the fuel tank and filled the system with 10 -20 psi of compressed air.

That forced fuel out of the system where the leak was.

My leak was under the tank.
The hose crimped to the fitting connected to the tank was letting air
into the system.

Thank You
Have Fun
RichC


.

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When the power of love overcomes the love of power the world will know peace.
Jimi Hendrix

Cool way to find the vac leak. Was it not dripping VO from there?

Ive also found the vac pump / plugging 1 end of line to be invaluable. I had to go back and teflon tape every threaded fitting to get it to seal. Also repl all the crush washers.

And the looped return works wonders (once the air is out). I think I gained back 15-20 hp when I looped return.

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Paul
Benz-less
I need an SDL !

It has to be somewhere before the IP. Everything in the IP and beyond is pressurized so a leak point would show up as dripping fuel, as opposed to sucking air. If the clear lines you installed show no air prior to the hand prime pump, and you checked the prime pump itself, so I would bet it's somewhere in the spin-on filter assembly.

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'83 300D Turrrbo 295K miles

Thanks for the help. Turns out it was the primer pump. $10 and am running smooth. Found it with the Mityvac, sweet! Ain't no turning back, now i need another merc for my daughter.

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84 300 D Turbo, 222,000 and rolling, veggie most of the time.
91 350 SDL veggie wannabe