Thread: bio fuels and fuel pumps

talking perfect world

bio diesel has better lubricity but is more viscous at lower temps and pressures

mix in impurities or dont make it right and who knows.

TDI300s operate under the margin for perfect bio causing problems in the mechanical way but the bio can take out the seals in the pumps/lines.

TD5's (and almost any common rail or unit injected engine) operate near or over the magic point where bio becomes problematic and even then if the bio is prefectly clean its not a problem till you pick up contaminants.

The viscosity in colder weather can cause problems getting through the filters but some clever use of heater hose soon sorts that out.

Thanks Dave, yeah the bio guy was full of scorn for the mechanic but then again he's got fuel to sell whereas the mechanic makes nothing out of it, except repairing the damage. Looks like I'll be sticking to the standard stuff. Anyway, sounds like too much hard work setting up a backyard refinery. Thanks for the advice.

dont be scared of running it in the tdi, I admit the process for making it seems a little daunting but in reality its not that hard.

search out the DR pepper method and you can make a couple of liters of decent enough grade to not hurt a TDI.

I havent done much of the making partly because the wifes wagon is the TD5 that can have very expenisve consequences if it decides it doesnt like the bio and partly because fozzy my sereis will run on whats basically filtered and de watered waste oil from almost anywhere.

for the TDI you can replace the fuel system complete for the cost of the fuel pump and one injector from a TD5

If you can find someone who will sell you good bio at half the pump cost of dino then you are well over the break even point for running a tdi on bio if you get through 50-60 tanks worth of fuel between major issues (excluding the spin on filter which I reccomend you change a lot more regularly)

if diesel was $1.20 per liter and you were only paying $0.60(cost of you making it OR purchasing from someone else) for 100% bio with the savings you make on fuel

every 5 tanks you can buy a new injector
every 20 tanks you can pay to have the seals replaced on the injector pump (assuming you take the pump off yourself) and have the pump serviced
every 50 tanks you can buy a new injector pump
every 200 tanks you can overhaul the engine

each individual line will still have you infront on the dollars.

those numbers are assuming that you dont outlay the money on other items EG to buy a new injector and a new pump you would need 53 refills.


for the TD5 ITd be 50ish tanks to replace the lift pump and about the same for each injector.

Good idea to keep a spare fuel filter or two with you if you do.

x2 on the filters and in winter youll find it hard to start

A hearty thanks to all of you for your advice. blknight, I got the initial impression it could be all trouble and I had wondered about the cost comparisons but obviously hadn't gone anywhere into the detail you've just kindly provided - many thanks. Will give it some serious consideration now. I just didn't want to get myself into trouble and extra repair costs by "saving" on fuel costs. Maybe I can use it more in summer. Got a bit of repair work to do in the meantime anyway - Only had the old dear for two months and have already done the brake pump, timing belt, rear ball joint, serviced the clutch master cylinder, got a slight leak in the brake master cylinder, need new shocks and various "consumables" in the suspension bushes, etc so I'm probably better off getting those done before I start home brewing. Thanks guys
cheers gerald

if you are DIY'ing the fuel, keep in mind that getting it de-watered etc is critical - a PO of my isuzu ran straight WVO (I think) through mine and the levels of gum were extraordinary... the sedimentor basically filled with gum and screwed the pump to the point where a complete re-build was required*. If you can do this yourself, the costs are not too bad but if you need to pay a specialist to do it, you can be talking $1000's so unless you are putting aside the $$ saved on diesel each and every tank, the money may not be there if/when problems arise...

* more regular PM is a requirement when using Bio, especially DIY Bio - fuel filters, sedimentors etc etc - my vehicle is effectively in storage with only monthly driving to keep everything ticking over by a non-landy enthusiast... this was obviously not enough and the PM was somewhat ignored (unfortunately).

Thanks Echidna, I atarting to think it might be easier to try working more overtime (when I can get it) than throw in the extra hours at home if I'm not sure what I'm doing. BTW, I had to look up wvo on google, guessed what po was , but pm has got me stumped. preventative maintenance??
cheers gerald