It seems that almost everytime I go out on my brand new Greasecar Vegetable oil system, I manage to hit these mysterious air bubbles that must be hidden within the fuel lines or something that stall out the engine. Thank God for that hand pump on the lift pump, or else I wouldn't have a starter anymore. I'm always wary now, at any time I feel I'm losing power, I switch back to diesel. I was told it could be the lift pump, but I didn't understand why that wouldn't affect the diesel. Any advice?

Make sure all your hose clamps are good and tight. How many miles do you have on you system? When I put mine in it took nearly 100miles to finally get all the air out of the system.

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I suspect you have air trapped in your greasecar fuel circuit. The looped return causes this problem. You need to install a "partial return" back to your grease tank to allow air to escape. If you really want to know more about how to do this, PM me. Also, if you replace your hoses with translucent polyurethane, you will be able to see exactly where any air leaks are coming from. This tubing is available at www.mcmaster.com.

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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

I don't know exactly how many miles, but I would imagine over 100, up to maybe 300. I've been pretty good at checking all the connections and I haven't found any leaks yet. I don't understand how air could be trapped in the fuel circuit, I've been cranking air through the engine.

I get the same problem. I've been using mine for more than a year. I have changed the lift pump, all hoses, clamps and it still get's air in the line when my rpm is over 3k. Even driving with diesel, you can feel a large lack of power over 3k rpm. I am clueless on what to do with it...it's so frustrating.

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My Primary Driver - '85 300CD - 4-speed conversion, 2.47 rear, lowered, euro headlights, rebuilding (not restoring so much)

Wife's - '08 Saab Sportcombi Aero

Riding a '03 Yamaha Warrior

Make sure the Greasecar three way valves are not leaking air. Some of them have the tendency to the casings loose.

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1983 123.133 California
- GreaseCar Veg System

The fuel return on the VO side is returned to the fuel supply line, so its like a loop. If air gets in the fuel line, it never leaves, unless it gets injected into the cylinder.

Running an extra long purge cycle should get rid of most of the air, but it won't get rid of all of it. To purge it, you can remove the return line from where it connects to the supply line and place it in a container, like a gatorade bottle. Don't forget to plug the hole in the supply line where the return line used to be. Then run the engine for a short time and it should purge all the air out. Be careful when you reconnect it so that you don't let more air in.

Also, check all the hose connections to see if they're tight.

That's the main pitfall of a looped return system, its hard to purge the air out if you have a leak.

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

If the Greasecar guy can't help you; try this:

Bypass the valve and go straight diesel to your pump. Use a clear filter/hose so you can see any air accumulation. If you get air in the mix with diesel, you have a screwed pooch. Every fuel line in the car is a candidate for replacement. Yuk! Let's hope it passes the diesel test.

If it passes the diesel test, go straight WVO. Draw WVO to the filter with a vacuum pump (there is no substitute for this). Take the "looped WVO hose" and place it in a 2-3 gal plastic container 1/2 full. If the loop starts passing air then look to the ususal suspects like the injector hoses.

If both tests are negative, check your "loop hose." Does it form a curly cue above the solenoid valve, then that configuration will trap air when the bypassed fuel drains down at shtoff. You could try to route it below the level of the bottom outlet on you solenoid valve. But, this is not your problem, only a suggestion.

This may sound silly, but does Greasecar replace the banjo bolt like Golden Fuel does? It doesn't sound like your fuel is circulating correctly.

Finally, providing all the testing is negative, get the car up to operating temerature on diesel. Then switch to WVO with no loopback. Let it go back to the diesel tank, it will stink a little but no harm will come of it. If none of these tests reveal the source, get a witch doctor. Let us know how it turns out.

Joe Marroso

The system should Not be looped....

The M.B. uses a 'displacement type' lift-pump, unlike all the usual rotary pumps conversion Co's are used to dealing with, The lift-pump in M.B. which doesn't perform at its best when the system is looped, Air ingress is just one issue that can happen in some cases, as well as power loss issues....(This is from experience over the years....)

Best use 'full-flow', with 8-10mm fuel-lines from veg-tank, with suitably sized fuel-filters

Are the Injector leak-off pipes in the 'loop' circuit...?--If so, 10-1, Thats where your air is getting in....

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http://i190.photobucket.com/albums/z...0TDnoplate.jpg

Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....

It wouldn't be a problem if it wasn't being injected. My problem is that air keeps getting injected and the engine stalls.

This is a diagram of my SVO system. The valves are the much-maligned pollack solenoid valves. They (presumably) worked OK for the PO, and have worked OK for the 7-8 months that I have used them for daily commuting & longer trips. The VO filter was a baldwin BF1212, now a fleetguard FS1212 10 micron filter, with a coolant filled copper coil wrapped around it to heat it. The final heat exchanger is a Doucette 1/2 ton coiled tube in shell purchased from frybrid.



This particular loop should not give headaches to a displacement lift pump the T location at V2 feeds the return flow into the intake, and make up of the injected fuel is freely taken from the VO line to the tank.

While I have oil consumption issues, soon to be addressed, I have no real problems with power or trapped air. Since the VO fuel sender is I believe corroded and gives no signal, I suck air now and then. This can be backfed down the VO line with my purge valve setting, as drawn. If excessive air is introduced into the system (filter change), I can select the appropriate system and push it out w/ the hand pump. The item marked 'sight glass' is as translucent right angle diesel line filters- whatever autozone sells for the final filter on the 240D. Another one, not shown is right above the LP/IP unit, so it's right between V1 and the engine. They let me see what fuel is in the respective circuits- always useful. Purge is verified when diesel is visible in both sight glasses (note to self-the new canola I filled the filter with looks just like diesel) WVO is typically dark brown. Air is visible in these filters, doesn't seem to restrict the flow. The banjo bolt is replaced with a solid bolt to prevent cross-contamination.

When I replumbed the system & added the HX, I used nothing special, 3/8" and 3/4" heater hose from autozone, Nylon T's & barbs from Mcmaster, stainless hose clamps from autozone.

I just spent the weekend driving around pittsburgh & surroundings with the family, challenging enough in a well powered automatic, let alone a 240D. I was able to reach or exceed posted speed limits on those crazy hills & get away from stop signs on 10-15% grades without much drama, VO or D2.

As far as SVO goes, I take my cue from frybrid, using a final heat exchanger & taking care to switch hot, block the banjo & purge properly.

If the banjo is not blocked, or if you do not purge properly, your diesel fuel system may be contaminated by VO. You might change your diesel filter.

Well, you can take your pick of suggestions, there are quite a bunch offered Try the simplest first...its a pain to go changing hoses once the kit is installed...try to get all that air out first..if you're sure you purged the air well and still have issues, then you may want to install some clear fule line somewhere.
Do you think your filter is clogged? That will make the engine stumble and suck air in any fitting past the filter.

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

My filter's brand new, it shouldn't be clogged, but I am using rather dirty oil, so how would I be able to check? And my system is fairly different from Moon161's, but I did block the banjo bolt. Also, this air problem is constant. I have not problem when operating on the highway because of the high rpms, it can just shoot the air right through the cylinder without me even knowing. Even on suburban roads it's not a huge problem. My biggest problem is when I idle at a stop sign or stop light and the oil pressure starts to drop and the engine starts to sputter out, but this only happens randomly.

You must have air actively leaking into the fuel lines then...if you're driving on the highways, you should have purged or run through all of the air that would have been in the fuel line.

If you go to an auto parts store, you can get an in-line fuel screen that's in a glass enclosure...you can use this as a sight glass. Get one with 3/8" hose barbs on each end...then you can put this sight glass at each connection, working from either the tank or the IP and work the other way, and figure out where your air is entering. Its a tedious PITA process, but I think that's what you'll have to go through. Be careful...sometimes the stupid sight glass can be the cause of an air leak and it'll always show bubbles

Good luck

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

I just noticed my engine at higher than normal temperatures yesterday and I checked the coolant level and found it pretty low, could it be that I'm leaking coolant into my oil, or would that do much more serious damage?