Big problem discovered with long-term WVO use in PD-TDI

For discussing the modifications needed for diesel vehicles to run with 2 tank veggie oil conversions.

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Big problem discovered with long-term WVO use in PD-TDI

Postby chasee » Wed May 21, 2008 7:28 am

I have 97K miles. Bought car new in 05, put kit in immediately. I set out to be the model WVO user, never cutting any corners, investing a lot of money and time up front to make sure everything was perfect.

I already posted my WVO processing procedures, so I'm sure most people would consider my WVO to be near perfect.

I so strictly follow warm-up and purge procedures that I'm basically OCD about it.

With all that, it makes sense that I have 97K miles without the slightest WVO related problem, on a PD engine which everyone said couldn't run WVO at all.

The other day I decided to replace/reroute my fuel hosing. Prettied it up for a grease gathering in NY, Greasestock 2008. The lines were the same since installation 3 years ago. Upon removing them from the filter head and solenoids, I noticed that the brass fittings on both had buildup inside them. Kind of like arterial sclerosis. Worse yet, the PD has two stock stainless fuel lines that route fuel along the valve cover. Stainless is not supposed to cause polymerization, but I could see it in there too. Yes, all of the points are POST WVO filter.

The hosing itself, and a plastic T for the return loop had no such buildup, so this was obviously a metal-only issue. The stuff is polymerized WVO, the same as you might find on a copper coil heat exchanger in your tank.
No way to tell if the tandem pump has this buildup too, but it would make sense since there's a lot of metal/WVO contact in there.

The big fear is a good sized flake dislodging and plugging an injector, or fuel supply being starved due to blockage.

I know I am somewhat unique with my number of miles on WVO, so this could be something that is very slow to present.

I ran a stock tank of B100 through, with 2 nights of sitting with B100 in the lines. This weekend I'm going to check the brass fittings again to see if it had any effect.
2005 Golf GLS PD-TDI, 5-speed. Grease Car kit installed right off the lot when brand new. Running on WVO about 85% of the time.
chasee
 
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Postby jburke » Thu May 22, 2008 4:44 am

Hi Chasee, BioDiesel from tdiclub.com here.

Thanks for your post. Sorry to hear of your problem.
I think the B100 will help. I've observed that new VO removes air polymerized VO stuck on the inside of my funnel, bd should do the same.
Perhaps an electric fuel pump plumbed in to circulate it overnight?
And a cheap $3 gas filter just ahead of the tandem pump to catch loose poly.
The bd may really loosen it up.

I was concerned too about that possibilty, so I checked inside my steel bodied wvo fuel filter for poly., but didn't see any. Did you see any in your filters?

Does your GC have the copper intank fuel heater?
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Postby chasee » Thu May 22, 2008 6:55 am

Yea, well Fred's almost got over the hump. But I think it burned up BK so much about the forum name change that he was just waiting to get his hooks into me. Did you catch my farewell diatribe yesterday before he deleted it? :lol:

Now, coincidentally last night, after I was banned for good, the Greasecar site was hacked, and a noob showed up impersonating Beetler. Yeesh.

Now that that's done with, yes, I have the copper heat exchanger in the tank. The thought that it starts the chemical process of polymerization which then propagates to the metal contact points down the line seems like a possibility.

My WVO filters have never shown any poly whatsoever, nor the actual aluminum filter head. Just the brass fittings and that stainless line.
2005 Golf GLS PD-TDI, 5-speed. Grease Car kit installed right off the lot when brand new. Running on WVO about 85% of the time.
chasee
 
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Postby SunWizard » Thu May 22, 2008 8:25 am

I agree that the copper in the fuel tank, combined with repeated excess heating and air exposure, could have initiated a poly reaction. I have seen this firsthand in several greasecar conversions, and there was a large build up on the exchanger. Once started its a chain reaction. You probably need to clean the tank exchanger better than what B100 can do or it may continue. Have you looked at it in your tank yet?
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Postby chasee » Thu May 22, 2008 9:11 am

Yes, I check my tank with every fill. From the get-go, I have noticed the typical "line" of poly that forms on the top of the copper tubing, like a horizontal stripe on a straw.

It tends to flake off "scabs" now and again, which the WVO filter catches. When I change the filter, I usually drain out a batch of these scabs. But other than that, no poly buildup on anything (except for what I now discovered).
2005 Golf GLS PD-TDI, 5-speed. Grease Car kit installed right off the lot when brand new. Running on WVO about 85% of the time.
chasee
 
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Postby jburke » Thu May 22, 2008 6:45 pm

"Did you catch my farewell diatribe yesterday before he deleted it? Laughing
"
Yes I did, wish I's copied it, it was excellent. And bkmetz should be getting plenty of Viagra spam soon, ;)

Impersonate Beetler?! Why? [/rhetorical]
I'm done there, too many boobs.

This report might be applicable:
https://www.greenroadenergy.com/images/ ... asfuel.pdf

assuming it 's > 70*F, can you lower the tank temperature ?
maybe by restricting the tank coolant loop with a series valve?
I'm assuming you have a supplemental heater under the hood.
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Postby John Galt » Thu May 22, 2008 6:58 pm

Don't heat the tank, it's problematic. Only heat the fuel pick-up. Polymerization is limited by the addition of petrodiesel. Add ~10% PD as a poly inhibitor and don't heat the tank.
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Postby chasee » Fri May 23, 2008 6:19 am

Naa, leave him be. I'm sure his life is filled with all manor of self reaped unpleasantness already. :wink:

I posted that farewell diatribe on Greasecar just for kicks.

Anyway, restricting coolant flow to the tank would restrict coolant flow in general, which is very bad for a PD engine that already runs hot. Since I'm up here in MA, gotta have tank heating, so I'm kinda stuck.

But since the PD actually heats the return fuel, even if only the filter was heated, I think what I discovered on the brass fittings and stainless line would still be there.

Tomorrow I'll explore and see if my B100 run cleaned anything.
2005 Golf GLS PD-TDI, 5-speed. Grease Car kit installed right off the lot when brand new. Running on WVO about 85% of the time.
chasee
 
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Postby John Galt » Fri May 23, 2008 10:54 am

restricting coolant flow to the tank would restrict coolant flow in general


obviously plumbed incorrectly
heated tanks cause polymerization
looks like yer pretty well pooched
good luck
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Postby chasee » Fri May 23, 2008 11:03 am

John Galt wrote:
restricting coolant flow to the tank would restrict coolant flow in general


obviously plumbed incorrectly
heated tanks cause polymerization
looks like yer pretty well pooched
good luck


Wait, huh? I've been successfully running WVO for 96K miles! Certainly not plumbed incorrectly. Basically all 2-tank systems have a heated tank.
How would you propose limiting coolant flow to WVO tank without restricting coolant flow in engine?
2005 Golf GLS PD-TDI, 5-speed. Grease Car kit installed right off the lot when brand new. Running on WVO about 85% of the time.
chasee
 
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Postby SunWizard » Fri May 23, 2008 11:03 am

chasee wrote:Anyway, restricting coolant flow to the tank would restrict coolant flow in general, which is very bad for a PD engine that already runs hot. Since I'm up here in MA, gotta have tank heating, so I'm kinda stuck.

A heated pickup doesn't restrict coolant flow. The advantage is it heats just the fuel in and near the pickup, not the whole tank. This means the VO you are running on is much hotter at switchover. It works fine down to -40F which should be good for your climate. And it means the entire tank doesn't get nearly as hot, which greatly accelerates your poly. The greasecar design of a tranny cooler suspended in your tank has proven for many reasons to be a bad design. I have seen many of them with bad poly buildups.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Postby BMW Fan » Fri May 23, 2008 12:39 pm

Well, in my case I always can blame the language for my mistakes.

But a guy running on veggie for so long and not knowing the difference between a heated tank and a heated pickup has me surprised.
How often do we have to repeat the same story.
Don't heat vegetable oil to much on the open were it is in contact with air.
One of the very basic rules. :!:

BMW Fan

http://www.crawldog.com/klausold/
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Postby chasee » Fri May 23, 2008 3:00 pm

Of course I know the difference, but you should understand that the heated pickup approach is not at all common, let alone one of the basic rules. Electric heated pickups are just bad news IMHO, fire hazard, etc..

Not sure where the transmission cooler thing comes in, the GC kit has always just had a copper coil. I've followed a lot of the poly investigations over the past 3 years, especially the study that was posted over at Frybrid, testing various metals and conditions for the effect on poly.

I'd love a setup that somehow just kept the tank/pickup at maybe 90F without complication to the engine's main coolant needs, and was also NOT electric. Certainly link me to some info. But I am also going to seriously consider a non-copper coil for my tank. I guess the fact that 3 years and (now) 97K miles later, and this problem was only discovered because I was doing some line rerouting, means that the poly issue is obviously not as bad as some would think. I hate any problems, even if they are minor and may only cause trouble a long time from now, so personally I want to address it.

Of course, this layer of poly might have happened within the first few months and then just stayed as it was. Pretty much coating the metal lightly and therefore making a barrier to any more.
2005 Golf GLS PD-TDI, 5-speed. Grease Car kit installed right off the lot when brand new. Running on WVO about 85% of the time.
chasee
 
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Postby SunWizard » Fri May 23, 2008 3:06 pm

I am not talking about an electric heated pickup. I am talking about coolant heated. They are common. Look at kits by Plantdrive, Frybrid, Vegpower, Goldenfuel systems, and the hotfox and arctic fox which are used by many others. The links to all of these are in the sticky at the top of this forum.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Postby jburke » Fri May 23, 2008 3:14 pm

An alternative to a heated pickup is no heat at all.

Use a veggie fuel pump to push the thick vo, and thin in the winter with kerosene to keep it liquid.
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