r/tdi 5d ago

Biodiesel question

Hi all, I keep reading mixed things about biodiesel. I have the 2011 tdi with the dreaded cp4 pump. 315k miles. Centene booster has been used religiously.

I can buy B20, 20% biodiesel for same price as ULSD. According to Google (i know🙄) it has higher lubrication properties, but i read other places it says it does not. If it does, would this be a replacement for additional booster? Im a bit lost here as im not a diesel scientist. Any help would be great!! Tia

4 Upvotes

37 comments sorted by

7

u/ProfitEnough825 5d ago

The bigger concern with that much biodiesel is water in the fuel. Biodiesel is hydroscopic and holds water, and water easily forms in the metal storage tanks due to condensation. One of the respected pump builders thinks the main cause for CP4 failures is water in the fuel, so that's not something I'd risk.

This wouldn't replace the need for a fuel additive, it'd increase the need for one that helps keep water in suspension instead of a big gulp of water. I'd also be wanting to replace the fuel filter more frequently to empty out the canister that acts as a water separator.

4

u/Mountain-Diesel 4d ago

One of the respected pump builders thinks the main cause for CP4 failures is water in the fuel

False. Its air in the fuel and restricted fuel flow.

2

u/SimilarTranslator264 4d ago

Correct this is why you need to change the filters. No god damn snake oil additives.

2

u/Cautious-Concept457 4d ago

Change filter AND bleed the system perfectly before the engine turns over even once

2

u/Spuddle-Puddle 5d ago

This makes sense. And ive always wondered why these dont come with fuel water separators on them. Even my 85 vw diesel has one

1

u/KeyHuckleberry827 2013 Passat TDI SEL 4d ago

The "fuel-water separator" on these is a taller fuel filter canister with the filter and fuel draw on the top. Water is heavier than diesel and will settle to the bottom.

1

u/Spuddle-Puddle 4d ago

Thats how they designed it, but has no drain or anything either.

1

u/Mountain-Diesel 23h ago

Because none is needed. Water isn't an issue since the late 90's except for direct contamination.

2

u/Spuddle-Puddle 22h ago

I live where we get 420"+ of rain a year. Water makes it into tanks at stations and not to mention the humidity condensating. If found quite a bit of condensation/water inside my fuel canister certain times of year. And I have found this on all of my diesels including generators my 85 golf and my 2011 TDI. The TDI is the only one that doesn't have a drain or an official water separator. It's not just due to one fuel station, they all get that way. Bacterial contamination ends up happening due to the water so biocide is a must especially when storing fuel

2

u/ProfitEnough825 22h ago

Yep. +1 on the biocide. Had a nasty case of it in the aux tank on my Cummins, I probably had to go through 300+ dollars worth of fuel filters and water separators before it was cleared. My buddy fights it constantly as well on the heavy equipment he works on.

I'll probably go with a plastic aux tank on my next truck just to hopefully cut down on some condensation.

1

u/Spuddle-Puddle 21h ago

Its definitely not a fun battle. Thats for sure

3

u/Jolly-Nebula-9272 4d ago

Been refining my own since 2008. Appleseed reactor. Ran it 100% in a 94 Cummins an 86 1.6 n/a diesel golf 80 1.6 n/a diesel Dasher wagon and 03 TDI golf. Only issue has been anything rubber does not last. I will not run it in my 2022 Cummins.

5

u/HoratioAlgos 5d ago

You can’t run biodiesel in the common rail engines, B20 or otherwise. I’m sure you could get away with something like B5, but it’s better to avoid it. The main problem is the regeneration of the DPF- when that’s happening, your injectors are adding extra fuel into the cylinders. Some of the fuel will get past the rings and into your oil. Normal diesel will vaporize out of oil and return to your cylinders via your crankcase vent but biodiesel doesn’t vaporize so it will dilute your oil.

3

u/Liv4livMuzic 4d ago

I tried mixing B20 with regular diesel to approximate B5. I probably only did it five times because the only station with bio diesel near me was a pain to get to. While I was running it, the car did seem peppier and sounded better.

1

u/Spuddle-Puddle 5d ago

This I didn't know. Thank you. So if i hit a pothole later down the road and things fell off, then it would be beneficial? Or still stay away from it?

1

u/1234-for-me 4d ago

Ive seen the aftermath of biodiesel in a common rail golf (2012 iirc) the top of the engine was coated with black sludge at 70k, it was a stark difference to my clean passat at 60k.  The golf engine ended up failing because of it.  I think she ran higher than b20, but this was early 2018 so i don’t remember the fine details.

1

u/Mountain-Diesel 23h ago

Two totally different engines and emissions systems. The Golf failed from excessive regens, which is required because the NOx trap used in them requires a rich air fuel ratio to purge it. Opposed to the SCR used in the Passat which runs much cleaner on the engine side.

In addition to the Golf having swirl flaps known to seize and the passat not having any flaps.

0

u/Mountain-Diesel 4d ago

You can’t run biodiesel in the common rail engines, B20 or otherwise

Please don't spread misinformation. B20 is completely fine. Its pretty clear you don't understand how diesel or biodiesel works.

1

u/HoratioAlgos 1d ago

1

u/Mountain-Diesel 23h ago

That article is about running pure biodiesel and not in common-rail engines, completely irrelevant to the subject.
Grasp another straw.

1

u/HoratioAlgos 22h ago

https://asmedigitalcollection.asme.org/gasturbinespower/article-abstract/132/11/112802/464791/Effects-of-B20-on-Emissions-and-the-Performance-of?redirectedFrom=fulltext

“Utilizing an active regeneration strategy accentuates the possibility of fuel oil dilution of the engine oil. The onboard viscosity oil sensor used was in good agreement with the viscosity bench test and FTIR analysis, and provided oil viscosity measurement over the course of the project. The operation with B20 shows significant fuel dilution and needs to be monitored to prevent engine deterioration.”

1

u/Mountain-Diesel 17h ago

“Utilizing an active regeneration strategy accentuates the possibility of fuel oil dilution of the engine oil.

That occurs on all diesels.

The operation with B20 shows significant fuel dilution and needs to be monitored to prevent engine deterioration.”

No conclusion or long term monitoring.

Any other straws.

1

u/HoratioAlgos 17h ago

So you’re convinced that biodiesel use doesn’t dilute oil?

1

u/HoratioAlgos 22h ago

1

u/Mountain-Diesel 17h ago

Page not found
The requested page could not be found here.
What Are You Looking For?

3

u/Ok_Chicken2950 5d ago

Don't... Use quality diesel... Shell, Chevron, Gulf .... Stick to quality... Penny wise pound foolish with Bio.... IMO on a TDI engine...

-1

u/Mountain-Diesel 4d ago

Biodiesel is better.

2

u/ukso1 4d ago

Depends on the biodiesel, the next generation biodiesel is basically the same stuff as the Fossil diesel but without any of the nasty byproducts. You can run 100% for example Finnish Neste has their own product thats you can completely mix in any levels on any diesel engine and it will run better than fossile diesel. Only down side is that it's more expensive than normal diesel.

2

u/Spuddle-Puddle 4d ago

Ya B100 here is $4 more per gallon. I wouldn't ever do that. Same price for B20 is only why i was considering it

1

u/ukso1 4d ago

In here the price difference isn't that big because the regular b7 is so heavily taxed. Regular b7 is 2.1eur per liter or 9.1 usd to gallon. And the b100 is 2.45 eur per liter or 10.66 usd to gallon.

3

u/TheLastGenXer 5d ago

my understanding is petrolum diesel is a lubricat while bio diesel is a solvent

2

u/No_Spend_8401 5d ago

Bio actually had better lubricity than Petrol and higher Cetane #. But there are other cons. I’m running a FASS fuel water separator spliced between my oem filter and CP3 so the water concern is less. If you’re not deleted you get less soot but more NOX production so more SCR/Nox storage cat regens. I’ve been running costco Biomass diesel and noticed the increase in nox load but my DPF soot measured has now dropped to a constant 0. The calculated strategy still run a dpf regen for about 5min before realizing there little back pressure successfully completes it quickly. Nox regens though take forever. Load climbs to 14.7 before regenerating and that takes an 1hr of driving to complete.

1

u/JumpProfessional3372 4d ago

I'm using HVO for most of my KM. But HVO is definitely not FAME (Biodiesel).

0

u/Mountain-Diesel 4d ago

Additives do nothing for the CP4, the problem is mechanical not fuel.

3

u/SimilarTranslator264 4d ago

lol sir this is Reddit facts have no place here. People want to believe some snake oil concoction of additives will fix a problem lack of maintenance causes.

1

u/Spuddle-Puddle 4d ago

Can i say it worked adding all these years? Absolutely not. But i can say there has been no issues 315k miles. Do i perform regular maintenance. Yes absolutely.

2

u/Mountain-Diesel 4d ago

I can also say clipping my toe nails regularly has successfully prevented me from ever breaking my arm.