[Vwdiesel] biodiesel requiring a rebuilt injection pump on an '84 Rabbit

David Cook vwdieselbunny at yahoo.com
Mon Mar 20 22:57:17 EST 2006

Hey Bryan-

The problem is similar to why you had your fuel lines
replaced.  Biodiesel can rot rubber parts.  

You should consider having your pump resealed with
biodiesel-proof seals.  I had a pump resealed a couple
years ago for about $200-250.  (Not a total pump
rebuild, but a reseal that included some new bushing
that required at least partial dissasembly of the
pump--I think it was the accelerator shaft bushing.)

My pump had developed a leak at the shaft for the belt
sprocket.  I was having problems with diesel leaking
out of the pump, so it would start hard (as pump
needed repriming) if it sat overnight.

That seal leaking got diesel fuel on the timing belt,
and since diesel fuel can also damage rubber, I
replaced it.

If you have original seals, you could very well
develop leaks in the injection pump, which could get
the timing belt covered in the fuel, which will
eventually damage it and cause it to break.

This stuff won't be immediate, though your belt may
not have much more time after the pump starts leaking.
 You will know the pump leaks when you get puddles of
diesel on the floor!  :-)

If you plan on using high concentrations of biodiesel,
I would start budgeting some money to have the newer
seals installed in the pump.  Then you won't have
anything to worry about.


--- "Bryan K. Walton" <bryankwalton at machlink.com>

> Hi everybody,
> I have a question for the list concerning the
> effects of biodiesel (in
> high % blends) on the injection pumps of A1s (my
> case -- 1984 Rabbit).
> I purchased this rabbit in December of 2005. It has
> approximately
> 121,000 miles on it. I've been running B20 in it so
> far. A few months
> ago, I had a mechanic upgrade the fuel lines to
> viton lines in
> preparation for me raising my concentration of
> biodiesel. I've
> purchased a new fuel filter and have planned to up
> my percentage of
> biodiesel to B60 sometime in April (and then go to
> B100 in June).
> Today, I read something on the Frybrid mailing list
> that made me halt
> my plans. Here is the link, to that thread:
> http://www.frybrid.com/forum/showthread.php?t=3571
> In this thread,
> Chris Goodwin, owner of Frybrid, states that when
> running biodiesel,
> "early VW products will need a rebuilt Injection
> pump or they will
> leak at the advance plate, then at the face seal,
> the biodiesel will
> turn the cam belt to mush and the engine will bend
> valves and need 
> rebuilding."
> I can handle a leaking fuel line, but rebuilding an
> injection pump is 
> frightening! And I don't even want to think about
> having to rebuild my
> engine. What is the story here? 
> Would Chris's scenario happen slowly enough that I
> could fix the
> injection pump before there was engine damage? Or
> are we talking about
> something that would happen almost immediately? 
> What symptoms would I
> see if Chris's scenario started happening to my IP? 
> Is there anyway I
> can determine what the seals are made of on my IP,
> short of waiting for
> disaster to strike?
> Any VW owners out there (with circa 1984 diesels)
> running biodiesel
> in high blends that can speak to this and their
> personal experiences?
> Thanks in advance,
> Bryan
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> Vwdiesel at vwfans.com
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David Cook
Red '86 Cabriolet Diesel Powered
Red '90 g60 Corrado 
Brown and White '78 Westy Campmobile "Bear"
and others in various states of disrepair
Pictures here: community.webshots.com/user/superdave5599

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