My mechanic said not to use biodiesel...

[cprboyle]

Hi! I had a 2001 Golf TDI years ago and ran it on biodiesel and loved it. I recently bought a 2005 Jetta 1.9L and took it to a mechanic to look over. They specialize in VWs. He said not to put biodiesel in it because it will swell some valves or gaskets or something (sorry I didn't get better info), and then when you put regular diesel back in it later, it causes all kinds of problems with the engine.

I basically bought the car do run biodiesel in, so I'm hoping for an excuse not to believe him... can y'all help me out with that? The station near me sells B20, and the other 80% is renewable diesel. Thanks for any info.

 

[CleverUserName]

It's the Renewable diesel that causes the seals to shrink and cause leaks. It's common with the ALH TDIs and it happened to me when I tried it. Unless you like chasing fuel leaks I'd stay away from it.

You must be talking about biodiesel oasis in Berkeley. That place is expensive for what it is, if you want a "green fuel" and don't care about chasing fuel leaks just buy regular R99, the sell it at the propel station on university avenue and it's significantly cheaper than Biodiesel Oasis.

 

[cprboyle]

@CleverUserName you're right, that's where I am.

I looked into what yo said and you're totally right. Maybe you already know this, but it looks like it's all about aromatic hydrocarbons. Aromatics cause some seals to swell; biodiesel has more than petroleum diesel, and renewable diesel has less.

Here's what this link said about renewable diesel, https://dieselnet.com/tech/fuel_renewable-diesel.php:

It should be noted that while these fuels consist of hydrocarbons, the hydrocarbons are predominantly paraffins. Petroleum fuels are a mix of several types of hydrocarbons including paraffins and aromatics. If a fuel consisting almost entirely of paraffins replaces a fuel containing significant aromatics, a number of challenges can arise, including issues related to sealing against leaks and solubility of fuel degradation products. Fuel distribution infrastructure and vehicle fuel systems containing nitrile rubber seals in contact with fuel swell when aromatics are present. If the aromatic content of the fuel decreases to sufficiently low values, the nitrile rubber seals shrink and fuel leaks can result. While modern vehicles rarely use seals made from nitrile rubber, these types of seals can still be found in older equipment and in the fuel distribution infrastructure.​

Here's more about biodiesel and its effects on specific types of seals, nitrile being of particular concern:
https://dieselnet.com/tech/fuel_biodiesel_comp.php

 

[atc98002]

I believe that this swelling issue is resolved with replacement seals (my mind is drawing a blank on the material used for the improved seals), and then it never happens again. The 2005 might even have the newer style that is OK with it. But even so, everything I've seen posted here over the years says it's actually an easy job to change the seals in the injection pump, which is where the majority of any leakage comes from.

 

[Lightflyer1]

Viton seals. Here is an example:

Deluxe Injection Pump Seal Kit for TDI

Don't replace that leaky VW injection pump, reseal it. A ton of customers have fixed their leaking TDI injector pump's quantity adjuster seals with this kit!

www.dieselgeek.com

 

[cprboyle]

Thanks!

 

[Gun-driver]

I’ve been running my ‘04 Jetta on anywhere from 20% - 100% of my made at home bio with no issues for for close to 175,000 mi.
Getting ready to turn 300,000 probably in the next two weeks. It does have a BEW motor though.

 

[Tdijarhead]

A 2005 doesn't have an injection pump like the dieselgeek kit fits. That's for the 99-03 ALH engines the 05 has a BEW and it has an in tank lift pump and a second tandem pump on the side of the head. I have no idea if those pumps will hold up to biodiesel or not. Why are you wanting to run the bio? Is it cheaper? Better mileage?

 

[IndigoBlueWagon]

Lug_Nut, one of the Club's first members, owned a couple of BEW engine TDIs and ran B100 in them with no issues.

What I've learned is that the aromatics in bio make seals and gaskets in the fuel system expand. If you switch back to ULSD, the aromatics will migrate out of the seals and they'll shrink, causing them to leak. If you stick with bio, or a reasonable percentage of bio, you are less likely to experience any issues.

 

[TDIMeister]

Biodiesel has little aromatics (these are compounds containing one or more benzene rings in the molecule). What distinguishes biodiesel from ULSD is that the fatty acids from the vegetable oil feedstock have one end of the large molecule snipped and substituted for a methyl group forming an ester - in the middle of the picture below, the left side of the long-chained structure containing oxygen (o) - by reaction with methanol and caustic lye. Not shown but implied on the far left of the long chains next to the —o– is the methyl group (CH3) that substitutes in-place of the much more complex branch shown in the farthest left of the below figure depicting a normal soybean oil molecule.



The overall reaction looks like this:

Looks complicated but it's not. I'll try to walk you through it: The first term is a fatty acid (e.g. soybean oil); the second is methanol (3 parts for each part of the fatty acid); the catalyst ("Kat.") is lye, e.g. NaOH; the third term is glycerol (1 part for each part of the fatty acid) and the last term is the methyl ester (3 parts for each part of the fatty acid). "R" can be any of the complicated-looking molecular chains from the upper figure; they appear in soybean oil in the percent proportions shown in the right of the top figure. There are no ringed benzene structures that look like the below, therefore no aromatics. The lack of aromatics is one of the good things about Biodiesel, because these are where soot particles tend to like to form and agglomerate.



Precursor of a soot molecule. Note that it's a bunch of aromatics together.

 

[[486]]

it makes your fuel leaks look like a deep fryer that ain't been scrubbed in decades
enough to make me avoid bio-d like the plague

it does do some stuff to buna-n (nitrile) rubber too, blending mandates are why there's a lot of viton in modern fuel systems

 

[kjclow]

Biodiesel has little aromatics (these are compounds containing one or more benzene rings in the molecule). What distinguishes biodiesel from ULSD is that the fatty acids from the vegetable oil feedstock have one end substituted for a methyl ester group - in the middle of the picture below, the left side of the long-chained structure containing oxygen (o) - by reaction with methanol and caustic lye. Not shown but implied on the far left of the long chains next to the —o– is a methyl group (CH3).

View attachment 116071

The overall reaction looks like this:

Looks complicated but it's not. I'll try to walk you through it: The first term is a fatty acid (e.g. soybean oil); the second is methanol; the catalyst ("Kat.") is lye, e.g. NaOH; the third term is glycerol and the last term is the methyl ester. "R" can be any of the complicated-looking molecular chains from the upper figure. There are no ringed benzene structures that look like the below, therefore no aromatics. The lack of aromatics is one of the good things about Biodiesel, because these are where soot particles tend to like to form and agglomerate.

View attachment 116072

Precursor of a soot molecule. Note that it's a bunch of aromatics together.
View attachment 116073

Thanks. Makes me feel like I'm back in Organic class.

 

[Lug_Nut]

Lug_Nut, one of the Club's first members, owned a couple of BEW engine TDIs and ran B100 in them with no issues.

It was B99, and the PDs were one BHW (2005 2.0 Passat), and one BEW (2005 1.9 Jetta).
The Passat ran fine, but the transmission shift points and the car's ergonomics were what prompted me to realize I'd never 'like' the car, so I chose to part with it. The Jetta was a manual and it fit me much better too. That one I liked a lot. The turbo bearings went, the rust was starting to progress, my commute needs were significantly shorter, so that car was donated. The later VW TDI with C.R. and their with post injection for catalyst were (are) incompatible with high percent bio and I got my current (pun) Volt.

Although my diesel car days are ended, or on pause, I still run my Bolens on the same, now three years old, B99 I last bought when I had the BEW Jetta.

 

[Vegged-Out]

Thanks. Makes me feel like I'm back in Organic class.

Organic Chemistry... It's what NIGHTMARES are made of!

 

[JohnTF]

There are so many variables that without details , it all beleavers on one side or the other , then other sides = many sides .

Depending on the yr. of manufacture / or kits used when a part of a fuel system is rebuilt , the seals & gaskets vary a lot from multiple manufacturers - and they change there products over time .

Then you get into what each individual says is bio-diesel , this has even more variables - especially the closer to home made , even the commercial producers vary .

Leave the subject out of the filter waste vegi , heated oil types [ not that quality bio-diesel can not be made from used fryer oil { not enough volume for commercial manufactures } ] .

So then we step into real bio-diesel = transesterification process - basically removes the glyserin .
But there are multiple processes to do this , the most common uses methanol , another process [ much less common ] is the water process .

Then especially the home-brew and smaller producers , is how well the wash , water removal , filter , PH balance etc.

Then back to manufacturers , the engineering is moving away for any concept of any kind of bio [ except maybe to keep seals / gaskets from reacting to mandated small % of bio ] so to lockout bio & keep petro diesel .

So the only way to know for sure is to rebuild fuel system yourself and make your own [ then only you are responsible for the choices ] .

Bio-diesel can be totally non-problematic , but only within limits and you have to match you fuel system to the fuel .

Probably the single biggest issue is - lack of volume for general use , as compared to petro diesel [ not including political , and vested interests ] ,
There are some options to deal with the volume issue , but with all that is working against bio , the volume solution is economically un-viable -- that is producing vegi oil by algae method [ now who's semi desert area are we going to use to grow the volume ? ] .

 

[Kitsune]

I ran with B80 for most of a decade without much in the way of seal issues. YMMV. Local stations run B20.

 

[Spdmini]

I put 40k miles on personally homemade biodiesel in a PD 15 years ago. I had one long crank on a hot day. I also ran it in my 12v Cummins, many alh and bews , and a Detroit 6.5. If you can handle a few unit conversions, you can produce a solid biodiesel.

 

[tikal]

It's the Renewable diesel that causes the seals to shrink and cause leaks. It's common with the ALH TDIs and it happened to me when I tried it. Unless you like chasing fuel leaks I'd stay away from it.

You must be talking about biodiesel oasis in Berkeley. That place is expensive for what it is, if you want a "green fuel" and don't care about chasing fuel leaks just buy regular R99, the sell it at the propel station on university avenue and it's significantly cheaper than Biodiesel Oasis.

Ok, what if you add a reputable lubricant additive to the Propel diesel, would that avoid the shrinking of the seals? I am coming to Northern California for a camping trip and I thought that I would like to try the fuel if the price is competitive (ok for Calif. that would be in the upper $3/gallon range I guess). This is on a PD/BHW engine (255K miles) run mostly with some kind of known lubricant or with the included up to 5% bio blend.

 

[CleverUserName]

Ok, what if you add a reputable lubricant additive to the Propel diesel, would that avoid the shrinking of the seals? I am coming to Northern California for a camping trip and I thought that I would like to try the fuel if the price is competitive (ok for Calif. that would be in the upper $3/gallon range I guess). This is on a PD/BHW engine (255K miles) run mostly with some kind of known lubricant or with the included up to 5% bio blend.

Diesel is currently $4.20-$4.50 here in CA. There are some discount places selling it and B20 for closer to $4.00 if you use gas buddy.

The 1 time I tried it in my 03 Golf it was blended with Diesel in the tank and it still caused a leak. You’re on your own…

I had some Renewable Diesel in a graduated cylinder, used it to fill up the fuel filter housing after installing a new filter. It was in the trunk and after a short time it started to break down (hydrolyze?) became hard and had a very unpleasant smell. Not sure if this was a bad batch or if the fuel itself is unstable but thought it would be good to add an update to this thread.

California has very high quality diesel #2, the best being from Mobil or Chevron IMO and it’s stable.

 

[tikal]

Thanks for the heads up. I guess is no go specially when home is a long ways back.

I believe Costco has some D2 stations in the state so that's an option for me.