greascar suggested that the cloth return line from the injection pump is leaking air into the system because the oil is under pressure and holes that wouldn't affect diesel would affect the vegetable oil. Is this possible?

i have 3 valves in my system.this allows me to use a fuel filter filler switch.
when i push this switch while running on diesel it opens up the return to veg
that goes to the loop (thus filling the fuel filter after i change it.
but this also backflushes all the veggie lines and pushes any air
back to the veggie tank and out of the loop.Quite convenient..
I have a frybrid system. Sounds like you definitly have an air leak somewhere.
I understand if you can park on a very steep hill facing down hill you may get some drips from the leak.

Do they mean the "cloth" lines from the injector returns? Because those are rubber lines with cloth woven over them. They do start to break down from extended use of biodiesel, but WVO didn't affect mine...a few tanks of biod and I changed mine to viton. They're easy to check, look at each injector and see if the "cloth" return line is snug on the nipple. IF it comes off easy, then it is probably leaking air...you can find replacement return lines readily enough, search for injector return lines.

The return line from the injector pump is a hard plastic originally, and most people use viton or something else that looks like rubber, there's no "cloth" involved there unless greasecar gives you something unique to use.

I have a 3-valve frybrid system too...did you rig up your own filter-filler switch? Because normally, when you are returning to the VO tank, it goes down the return line, not the supply line..do you have something to turn on your purge valve and your return valve?

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

well, the car does have a quarter of a million miles on it and I don't know if the lines have ever been replaced, could they just leak because they're old?

It's generally thought there should <500 PPM of suspended/emulsified water in WVO. In greater quantities, others have found it to contribute to injector fouling and IP damage due to cavitation. If WVO is properly settled & stored will be no visible vapor phase in the oil, even when heated to the smoke point. That being said, on a stock greasecar kit, w/ no secondary heat (FPHE, line heaters, etc) & stock 82C thermostat, a WVO temp >212F is mighty unlikely at any time. A simple scintillation ("hot pan") test will tell you more about moisture in your oil.

I'm thinking BS. Why should it be under negative pressure? If it is, I'd replumb- you're definatelly sucking hard to get oil where you won't get it.

They could, check them. But on my '74 they're great..so great in fact that i couldn't pull them off the nipples without damaging the lines, so I left them. I figure the biodiesel will loosen them up eventually

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

I tried to pull them, but they didn't come off easily, how hard should I be pulling? Also, I noticed that the injectors for cylinders three and four were wet. It smelled like diesel.

When you push them on the nipples, they should be snug. If they're leaking, they;ll make the area around the injectors wet, but leaky heat shields will do the same think (I think).

Unless they're REALLY loose, I don't think you'll be sucking air in here...at most, it may be under negative pressure at the last connection to the top of the spin-on filter, but even there, the injectors will be returning fuel and any of your leaks will probably spill fuel out, not leak air in.

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

what does a leaky heat shield mean?

Don't worry about that right now. Those little rubber injector return lines can cause your car not to start. If you see wet around injectors look there first.

1) Tighten injctor nut on top of injector with 17 mm wrench. If it is tight and snug you are good. Crank with paper towel around injector to dry it and see if it is leaking there.

2) Replace those rubber lines. If you have to just go to oreily's, rip a line off your car, take it in and get a fuel hose to match the size. My oreilly fuel hose for injector lines has lasted over a year. works good.

replace anywhere there is that rubber hose if you are in doubt. After a while you will kind of get the hang of it. It does not take much. Heat and a mixture of fuels degrades hoses. They dry and get hard and leak around hose clamps. Good hose clamps can make a difference. Get the ones like MB uses at Pep Boys. Ones for "Fuel Injection"

Story, my wifes 1998 Jetta quit running. she called me, "Car wont run on diesel or veggie. Starts then dies. It is sucking air." The problem was, the 6 inch piece of hose from the 3 way supply valve to the IP was leaking at the IP. After a year, it had gotten hot and degraded. The hose clamp on it was not too good. It was a little wet around the ip. I had some 5/16 hose in my car. Replaced it, and it worked good. Her IP was 5/16 ID and the 3 way valve was 3/8 ID. I forced the 5/16 hose onte the 3 way valve and clamped it. My experience is that too big of hose are more prone to leak after a while when they dry ad degrade.

Bend all your return lines at the nipple on the injector and look for a crack. That will cause car not to start.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

DAm thats a pretty mechanically inclined wife. Mine just says "Im not taking your car".

Somewhere there must be a 3/8 to 5/16 adapter sleeve. Ive got like 10 lines with that scenerio, hate forcing the 5/16 onto 3/18 but its worked so far...

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Paul
Benz-less
I need an SDL !

Mcmaster 5463K156

The return lines are definitely wet, they're probably porous, I'm going to replace those. I have another problem, though. I noticed my oil smelled kinda funky in addition to a drop in coolant level, but after I drained the tank and the car was running with coolant at 80 degrees celsius, running temperature, nothing in the tank was apparently leaking. Could it just be that the oil is going rancid? If it is, is that still safe to burn?

More trouble: On a 3 hour trip up to Maine, I encountered intermittent loss off power on wvo. I had already replaced the leaky return lines and it was working for sometime until this trip. I proceeded to replace the rest of the return lines, thinking they were leaking air as well, but the problem persisted. Whatever the problem is, it goes away completely on diesel and, on wvo, it's not enough to stall an idling engine, it only runs rough.

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1983 240D 3.0T 4-speed manual, now sold

1989 Subaru GL Wagon 5-speed Touring Edition