Engine ruined by Biodiesel?

yitzak1388

New member
Joined
Dec 3, 2019
Location
Oregon
TDI
2011 golf tdi
Hi,

This guy on craigslist is selling an 80s caddy with the 1.5l diesel and says the engine stopped running due to use of biodiesel. Is this possible? Is it possible to clean and save the engine or is it trashed? I'm messaging for more info, just wanted your guys opinions. I'm interested and may be buying because he only wants $800.
 

atc98002

Veteran Member
Joined
Nov 24, 2006
Location
Auburn WA
TDI
2014 Passat TDI SEL Premium (sold back), 2009 Jetta (sold back), 80 Rabbit diesel (long gone)
Hi,
This guy on craigslist is selling an 80s caddy with the 1.5l diesel and says the engine stopped running due to use of biodiesel. Is this possible? Is it possible to clean and save the engine or is it trashed? I'm messaging for more info, just wanted your guys opinions. I'm interested and may be buying because he only wants $800.
I can't believe BD could trash an old IDI engine. They could run almost anything. Worst case might be having the injectors cleaned or rebuilt. But BD isn't going to damage anything. If they ran it in too cold of temps that might have sludged the pump up, but warmer weather should clear that.
 

Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
Proper biodiesel won't do that. Bad biodiesel and or other oil based products some people try to use can stop the engine. Probably hasn't ruined the engine but may require cleaning out the whole fuel system and replacing injectors and such. I would be more suspect of the belt jumping out of time or losing teeth and such. That will ruin an engine or at least the heads/valves. First thing to try is to turn it over by hand 4 or more revolutions to see if there is any interference issues. If so just run away unless you are ready to do a bunch of work and spend some money. Same if the fuel system is clogged. At the least the tank, lines, pump and injectors will need to be cleaned.
 
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scooperhsd

Top Post Dawg
Joined
Aug 19, 2003
Location
Kansas City KS
TDI
NB, 2000, RED(5 Speed conversion) 2015 Golf SE
+1 - Biodiesel shouldn't do anything (except as noted above). However - if the seller attempted to use WVO instead, and then it gelled up because it got cold - well, that could be a source of problems.
 

philngrayce

Veteran Member
Joined
Oct 18, 2004
Location
Connecticut
TDI
'02 Jetta, '06 Jetta, Both Gone '13 Leaf, Gone Liberty CRD, Subaru Forrester and MB300SD
I agree with all the above posts, especially Lighflyer1. Be very cautious - the engine may well be destroyed, and because it was running on biodiesel the owner blames that. You should probably assume the engine needs rebuilding or replacement, until you can prove otherwise. Unless the body is in great shape, or you just love those cars, the price may be $800 too high. That said, they are interesting cars, it would be fun to own and if the engine is good, it will probably run on anything.
 

Lightflyer1

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Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
Having been down this path with a $400 2003 Beetle I can guarantee you, you will spend more money on it than it is worth having the car for. I have bought better $800 cars that were running and passed inspection.
 

atc98002

Veteran Member
Joined
Nov 24, 2006
Location
Auburn WA
TDI
2014 Passat TDI SEL Premium (sold back), 2009 Jetta (sold back), 80 Rabbit diesel (long gone)
I will say one thing as well. VW switched to the 1.6 IDI in 1981, which I believe was the same year the Caddy came out. My 1980 was still the 1.5.

And I can't believe that Bio-D, in and of itself, could ever damage one of those engines. I bought mine with the engine disassembled, because they had warped the head running out of coolant. I replaced the head and drove it for another 30,000 miles before discovering they had also cracked the block. Replaced the short block, drove it another 60,000 miles, then sold it to a co-worker. There was no such thing as Bio-D back then, at least to my knowledge. But plenty of those old things ran on WVO or such. As mentioned, cold weather could gum things up, and at worst it might need a new set of injectors and piston rings. How enthused are you about pulling the head and doing the work yourself? For $800, I might consider it myself, assuming the rest of the truck is in decent shape.
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
As Lightflyer1 said, if it was good quality biodiesel, which met ASTM 6751 standards, it is not at fault. If it was somebody's home brew, however, that's a totally different story.
 

yitzak1388

New member
Joined
Dec 3, 2019
Location
Oregon
TDI
2011 golf tdi
Thanks for the responses guys! atc98002 I'm more than willing to pull the head. I almost bought a different one for the same price that had a bad head gasket, but it sold by the time I messaged the guy. I'll definitely check the timing as lightflyer1 said. My only issue is that his issue sounds unknown and if I can't troubleshoot it, I'll just resell. I'll be trying to talk him down on price so that I hopefully won't lose any money. Preferably though, I'd rather know what I'm getting into than opening a can of worms. We'll see...
 

Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
Non running cars aren't worth much generally speaking, especially older ones with no following and not in good shape. Unless this thing is rust free and in decent shape and the engine turns over freely, I would offer half what he is asking. That is the haul away price for the junkyard to come and get it, max.
 

atc98002

Veteran Member
Joined
Nov 24, 2006
Location
Auburn WA
TDI
2014 Passat TDI SEL Premium (sold back), 2009 Jetta (sold back), 80 Rabbit diesel (long gone)
I agree that the rest of the car should be in decent shape. I remember trying to find a Caddy to restore about 10 years ago, and I couldn't find anything that wasn't half rusted through or completely trashed. But I'd likely still jump at a clean Caddy with a bad engine. Always liked the car. :)
 
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