My 85 300d is set up to run WVO. I have a two tank system, hih, 2 3way valves, plate HE in front of IP, HE in wvo tank, heated filter in trunk and aux pump after the filter. My question is about the fuel connection. I teed into the diesel line between the diesel filter outlet and IP, rerouting to my 3 way valve. Works fine. When I switch to WVO, I get diesel returning to my wvo tank, not grease. I am going to use some dye to see if grease is flowing to the IP. I do not think it is. So, my question is, did I tee off the correct diesel line to my 3 way valve or not? I was stupid and tired, I should have used dye before jumping to wvo. I used the same set up on a vw rabbit with good results. Any ideas? Maybe a bad 3 way valve or electrical connection. I will double check those in the morning.

You need to re-route your diesel fuel lines so that the diesel goes through both filters before the lift pump. The stock configuration has the fuel going through the in-line filter, then the lift pump, then the spin-on filter, then the IP. For VO to work, it needs to go in-line filter, spin-on filter, lift pump, IP (you'll have to be creative making that sharp U-turn without kinking the hose between the lift pump and the IP). Also, you have to plug the banjo bolt on top the spin-on filter with JB weld, or replace it with a solid bolt.

Once that's done, the diesel path should go through both filters, then to the supply 3-way valve (no T's are involved, you route the fuel line from the spin-on filter right to the valve). The VO should also go through its filter and FPHE and right to the supply 3-way valve. The outlet of the supply valve goes into the lift pump. You really don't need an extra lift pump on the VO side if you're heating the oil sufficiently (and it sounds like you are) but it can't hurt as long as it turns off when your on diesel.

For the return...the return line comes off the top of the spin-on filter (around the plugged banjo bolt) and goes into the common port of the return 3-way valve. Then you connect the diesel tank return line to the normally open port and the VO tank return line to the normally closed port. That's it.

The reason you have to re-route the diesel fuel to begin with is the lift pump is mechanical and will pump whenever the engine is running, so you can't block it off, which is probably why you're getting diesel in your VO tank. If your VO supply is T'd into the diesel line just before the IP, the lift pump is probably still sucking diesel and mixing it with your VO. So your VO tank may eventually overflow if you run it long enough.

Did you buy a kit or put one together yourself?

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

what up dakota, pizzachef's instructions are wrong according to a stock greasecar installation, a diagram of which can be viewed here:

http://www.greasecar.com/forum_topicview.cfm?frmtopicID=16654

It's a helpful diagram to have, especially if your system essentially contains the same components, which it sounds like yours does. Only change I'd make to this diagram is where you T in for the return--go AFTER the grease filter instead of BEFORE it. This way, when you purge, your filter backflushes with diesel; also your return fuel when running grease will not repass through the grease filter (it's already gone through once). Both of these steps will exponentially increase your filter life. No kidding.

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JBG
1985 TD wagon, 228k
running on grease since 3.07
AUSTIN, TEXAS

Ok, I think I see the issue. I have pressure coming from the IP into the valve causing the diesel to continue through the valve even though I turned the port off and activated the grease port. If I reroute the diesel line to go to the primer pump after the 3 way valve, I loose that pressure that is forcing diesel into the grease port. Am I correct? Didn't have this problem with the rabbit, but the diagram is really helpful. Thanks.

I forgot, what is the issue with the return banjo bolt? I am returning fuel to the wvo tank, not looping. I use a hih for the return and fuel line so I have plenty of heat. Some people say not to mess with the bolt because it is needed to purge air when on diesel. thoughts?

That's a really nice diagram, it shows all the Mercedes components very well. But my instructions are for a system with a full return, which I think is what Dakota has, the greasecar system does not have a full return, the return T's into the supply line like you said. If you don't have a full return, there's no way to purge air from the system unless you flush diesel all the way back down the supply line, through the filter and to the tank...pretty wasteful when diesel is over 4 bucks a gallon. With a full return, you only have to purge past the return valve to get air out.

I think that's what's happening (and it would be the lift pump...the one with the manual primer pump attached...that continues to provide fuel pressure to the closed port of the supply valve, not the injector pump), but I don't know how much diesel would be able to bypass the closed port of the valve...its hard to say without being able to look at how the system is plumbed. I'm not familiar with how the old VW's are set up, but I'm guessing there wasn't a lift pump between the two diesel filters.

If you look at the diagram of the greasecar system, you can see that the injector return lines and the IP return line all come together at the banjo bolt on top the filter. This fuel can then drop right into the filter without having to be returned to the diesel tank. This will also allow VO to drop into the diesel filter. So to avoid this, you can have the IP and injector returns come together before the banjo bolt, go through the return valve, then go into the banjo bolt, or just plug the bolt. I'm not sure what exactly you lose by doing that, because any air in the system gets flushed back to the fuel tank. It may have to do with manually priming the fuel system, which I've done a few times with the bolt plugged...so I'm not really sure, maybe someone else will chime in and enlighten us

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

Followed the diagram, no problems, works great.

Dakota, glad to hear it. It is a very helpful diagram to have. Pass it along!

Peace,

__________________
JBG
1985 TD wagon, 228k
running on grease since 3.07
AUSTIN, TEXAS