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Volkswagen TDI's Description

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  #1  
Old 11-02-2008, 03:20 AM
Coyo~ Coyo~ is offline
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I finally got my Jetta towed to a local mechanic who has a VAG-COM and the know-how to use it. All they did was drain the fuel, blow out the lines, and refill with diesel. Timing was still perfect and the other readings were normal as well.

Well, not every reading. My coolant temp sensor was reading at -15C. Anyone know what's up with that? I'm wondering if this was an intentional setting to compensate for WVO?

Anyway, it looks like the problem was exactly what I suspected: the oil did not mix with the deisel when I poured it in, and the system took up pure, cold oil and bogged down. Whey they drained the tank they said it was still thick, and that's after several weeks of sitting idle, plus being driven and then towed over my long, bumpy driveway.

I think I'm going to wait until next spring/summer before going all-out with the WVO so I'll have some time to get things straight before winter. I think I'm going to inspect the entire Elsbett conversion to make sure it's still intact after having been looked at by so many mechanics who don't know anything about it.

Dan
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  #2  
Old 11-02-2008, 03:33 AM
john galt john galt is offline
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Quote:
the oil did not mix with the deisel when I poured it in
That's perfectly normal. Those who run fuel blends successfully always premix the VO with diesel.
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  #3  
Old 11-05-2008, 12:05 PM
jburke jburke is offline
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Quote:
My coolant temp sensor was reading at -15C.I'm wondering if this was an intentional setting to compensate for WVO?
That sensor is a known high failure rate item.
Replace it if it's no good.

Because you don't have the schematic to your kit, you and your mechanic can't know that this may be the sensor that the kit forces to a low temp. to trick th eECU into keeping the g.p.'s on longer. You may also have an open circuit in the wiring.

Measure the temp. 5 minutes after starting. By then the kit will not be forcing a low temp condition and you should get the real reading from the sensor.

Without a schematic, you're shooting in the dark.

There are two coolant temp sensors.
The kit only forces one of them low.
IIRC The sensor in the lower hose is forced
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http://ctbiodzl.freeshell.org/votdi.html
and a '92 F-250 with only a FPHE
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Old 11-05-2008, 12:18 PM
jburke jburke is offline
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Quote:
I suspected: the oil did not mix with the deisel
1. an els. s-t can start on 100% vo @ 45*F
2. you started on the contents of your injectors, not your tank.
3. assuming the wvo is filtered to < 5 microns the wvo and diesel will mix in the tank. they cant remain separate.
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http://ctbiodzl.freeshell.org/votdi.html
and a '92 F-250 with only a FPHE
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  #5  
Old 11-05-2008, 02:32 PM
SunWizard SunWizard is offline
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Quote:
Originally posted by jburke:
3. assuming the wvo is filtered to < 5 microns the wvo and diesel will mix in the tank. they cant remain separate.
If there is some PHO, that can always separate.
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Old 11-05-2008, 02:39 PM
jburke jburke is offline
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Quote:
If there is some PHO, that can always separate.
I used PH WVO and never experienced this if it was well filtered. I did see it with 100 micron filtered PH WVO.

In any case points 1. and 2. would be the factors that controlled starting. The tank could be almost empty and 1. and 2. still determine starting.
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Single-tank Elsbett VW TDI
http://ctbiodzl.freeshell.org/votdi.html
and a '92 F-250 with only a FPHE
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  #7  
Old 11-06-2008, 12:00 AM
Coyo~ Coyo~ is offline
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On the day the car stopped, I started on diesel (what was in my injectors). I had just dumped some room temp wvo into the tank - about 5 gallons of oil into about 5 gallons of diesel aready present. The car had been sitting outside all night at around 40-45F, maybe cooler. The oil was filtered to 5 microns absolute and dewatered by heating to evaporate out the moisture. The car died after about two miles, with symptoms being a sluggish feel, no acceleration, and then the motor stopped completely.

I got it to start once and run for one or two minutes. The shop was able to replicate this, even with a new primary filter. It wasn't until they drained the tank and blew out the lines and replaced with diesel that it started and stayed started, and has run perfectly ever since. So the fuel - or at least the way that the fuel interacts with the car - was definitely the culprit. When they drained the tank they said that the oil did not seem to have mixed, as it came out thick.

I don't have a thermometer on my boiling pot, so I wonder if the oil can be ruined by heating too hot?

What is PHO?

Dan
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Old 11-06-2008, 03:02 AM
SunWizard SunWizard is offline
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Heating doesn't evaporate the water, even at 350F in a fryer, see:
Test Methods for Water in VO
PHO=partially hydrogenated VO, it can separate out when <45F and is very thick, same story with animal fats, see:
You have white crap in the bottom of cubies and barrel?
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  #9  
Old 11-06-2008, 03:27 AM
Coyo~ Coyo~ is offline
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I tested before and after using the hot pan test. It showed lots of water before and none after, so I assume it did remove water.

The PHO may be the clue, as I have recieved quite a bit of that from one restaurant and most of it is currently in the barrel that I drew this oil from. I think this solves the mystery!

Dan
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99.5 Jetta TDI, Elsbett single-tank (incl. modified injectors & glow plugs, FPHE, heated filters), running on WVO/Diesel blend
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  #10  
Old 11-09-2008, 04:39 AM
Coyo~ Coyo~ is offline
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I really wanted to test my theory that my stall was caused by hydrogenated oil that had settled out in the tank. To test it I added back into the tank almost five gallons of fuel that I had siphoned out of the tank when the car stalled. It was siphoned from the top of the tank and was watery like diesel but colored like oil, so I'm sure it was a good mixture overall. I allowed it to sit out in the cold for a couple of weeks and no settling could be detected.

Since I put this back into the tank the car has been running great. I'm now more confident than ever that what I experienced was the settling out of hydrogenated oil, which remained thick and hard to pump.

Dan
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99.5 Jetta TDI, Elsbett single-tank (incl. modified injectors & glow plugs, FPHE, heated filters), running on WVO/Diesel blend
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  #11  
Old 11-11-2008, 11:33 AM
jburke jburke is offline
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Dan,
I had a similar failure in my s-t once.
It turned out to be a non functioning electric fuel filter heater. It's fuse had popped long before, but you don't know till you really need it, at 40*F. The elec. htr should be too hot to touch withing 30 seconds of starting. It ensures fuel flow in the first few minutes before the engine coolant warms the fuel in the heat exchanger.


There are two things you can also do in this situation that may help. Thick fuel causes a restriction at the fuel filter, the smallest opening.

1. OPen the valve on the backup fuel filter. This will double the fuel flow. Commonly done in winter or emergencies.

2. Manually force fuel through the f.f. using the hand pump. This saved my butt one day at 18*F outside running 80/20 WVO/dzl. The engine died after 3 minutes running. But I was patiently able to force enough thick fuel through to restart and dilute with diesel at a gas station.
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http://ctbiodzl.freeshell.org/votdi.html
and a '92 F-250 with only a FPHE
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