Danger in heating no 2 diesel in a veg oil system? - Diesel Forum

Monte1 · 12-26-2006, 11:45 AM

In purging the wvo from a system I've designed for a Mercedes, I will end up with no 2 diesel at shutdown in an electric wvo fuel pump and in the wvo fuel filter. On startup, the system will turn on the pump and heat/circulate diesel in a loop until coolant temperature reaches 160F, at which time the solenoid valve will open and the car will run on veg. oil. The reason for this design is to insure that the pump doesn't get locked up with solid grease after shutdown. Will there be any problem associated with heating the residual diesel to 160F? Am I looking for trouble by doing this? [img]/ubbthreads/images/graemlins/shrug.gif[/img]

fordnut74 · 12-26-2006, 12:41 PM

Monte- You are perfectly fine at that temperature. The Autoignition temperature of diesel is 410F. Backfilling the WVO side with some diesl is one of the ways my system works as well. Helps reduce any shockloading by presenting a an increasing WVO strength once the system comes on.

Monte1 · 12-27-2006, 02:38 AM

Thanks for the comment, FN74. I have been following your posts for a couple years, even through the sandbox times. Thank you for your service to our country. My war was Vietnam.

I'm wrestling with some of the design aspects of doing a system in a Benz. I don't want to modify the original diesel fuel system much, so am wrestling with using the mechanical lift pump and a wvo electric pump side by side. As I figure out the Benz system, it may become clearer how to do this well. In looking at the Frybrid system, it seems like they purge the lift pump and IP but not the wvo filter. They are also not looping their fuel line through the coolant heating system and back to the intake of the pump. One of the results of this approach may be the "hesitation on switchover" that I have read about. The Vegistroke system seems to have solved this on Powerstrokes. I'm not sure what the correct migration path would be to a mercedes IDI to get similar performance, but I'm thinking about it so much, my mind aches.

The fuel pump loading issue you point out is one of the things I suspect has been a reason for early pump failures experienced by some of our forum guys. If you have any additional thoughts, thanks in advance! [img]/ubbthreads/images/graemlins/smile.gif[/img]

hheynow · 12-27-2006, 08:14 AM

I replumbed my SVO system so the rear tank always flows through the heat exchanger. I see rear fuel temps of 160*F without a problem with blending down to B20. An added benefit is that when it's cold outside, the heat prevents the bioD from gel clogging of the fuel filter. Since #2 loses lubricity when heated, adding a lubricity additive is the prudent thing to do...but with ULSD, the additive should be used regardless of adding heat.

Monte1 · 12-27-2006, 10:02 AM

Doesn't adding biodiesel to wvo improve the lubricity anyway? Not sure if a lubricity additive would improve things much in the rear tank, but I think you are correct about needing it 100% of the time with no 2 ULSD fuel. I was wondering if just adding a bit of biodiesel to no 2 would improve lubricity like Stanadyne would.

hheynow · 12-27-2006, 04:39 PM

[ QUOTE ]
Doesn't adding biodiesel to wvo improve the lubricity anyway?

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[img]/ubbthreads/images/graemlins/confused.gif[/img] I've added bioD to wvo, but just to clean the fuel lines. Where did you hear that wvo lacks lubricity?

[ QUOTE ]
I was wondering if just adding a bit of biodiesel to no 2 would improve lubricity like Stanadyne would.

[/ QUOTE ]

Yes. B2 seems to be the minimum blend sold so I'd say it was added to #2 for the lubricity benefit. How little is "a bit"?

Monte1 · 12-29-2006, 12:43 AM

Regarding the lubricity of vegetable oil, here is a quote from an article I read on a google search from National Geographic:

"One of the roadblocks to the market appeal of vegetable-based lubricants is their unreliability at both high and low temperatures. When they get too hot they oxidize and break apart, and when they get too cold they solidify. Neither of these scenarios bodes well for the engines the oil is meant to protect."

I don't know what this means about mixing wvo and biodiesel. I presumed that since biodiesel has good lubricity characteristics at a wider temperature range than wvo (difference in solidifying temperature), the addition of biodiesel to wvo should improve the lubricity characteristics of the wvo. Make sense?

hheynow · 12-29-2006, 07:01 PM

That's a fairly general statement. Sure heating WVO to it's smoke point will damage the oil, but who heats it that much? Running WVO between 160*F and 180*F is the target temperature, which is what the SVO/WVO converted systems aim to reach. The same can be said about #2. Run it too hot and it will also lose its lubricity. As far gelling WVO, yes it does happen at different temps with various oils, but having a heated in-tank fuel pickup solves that issue. Diesel #2 also gels but at sub-zero temps.

IMO, running WVO is a commitment to understanding and dealing with gelling, keeping on top of fuel filter clogs, keeping your oil source secure and continually filtering, settling and de-watering ones oil. It's not suited for everybody, but those who accept the challenge (and headaches) reap the benefits. I still never plan on blending bioD to my WVO for the specific purpose of increasing the lubricity. Like I said earlier, I will run it with WVO to clean the front tank and its fuel lines.