PD Tandem Fuel Pump Leak, Biodiesel?

Geomorph

Veteran Member
Joined
Oct 17, 2007
Location
Sacramento, CA
TDI
2005 Golf and 2002 NB
Hello all
I have 2005 Golf and recently had my fuel pump replaced because of a slow fuel leak. This is the fuel pump that is mounted on the side of the PD engine that you can find by following both fuel lines from the fuel filter. I had been using B100 for about 9,000 miles and the dealership told me that biodiesel eats through the soft parts inside of the fuel pump causing leaks. The car still ran fine before I got the pump replaced but I definitely noticed that it seemed to run smoother after the replacement, even with 100% #2 diesel. So my questions are:
1) Has this happened to anyone else? You might not even notice it unless you look at it and see if it is covered with fuel. Mine was dripping down the engine, around the transmission, and leaving a small puddle of black biodiesel smelling liquid on the inside of the bottom cover. There were no drips on my garage floor. It seemed like it probably could have lasted longer but then maybe completely blown out at some point.
2) Is there any way to prevent this and still use greater than B5? Does anybody know of any rebuilds with more resistant materials?
 

runonbeer

Maintenance EnthusiastVendor
Joined
Apr 15, 2002
Location
Austin, TX/Chapel Hill, NC
TDI
'00 Golf 02M, '10 Golf 02E, '02 UTE 02M
Link to recall notice

Campaign Number:
04V586000 Date: 2004-Dec-15

Component: Fuel System, Diesel

Defect Summary:
ON CERTAIN PASSENGER VEHICLES, THE HIGH PRESSURE DIESEL PUMPS WERE PRODUCED WITH AN IMPROPER FASTENER, WHICH COULD ALLOW DIESEL FUEL TO ESCAPE FROM THE PUMP.

Consequence Summary:
FUEL LEAKAGE IN THE PRESENCE OF AN IGNITION SOURCE MAY LEAD TO A FIRE.

Corrective Summary:
DEALERS WILL REPLACE THE DIESEL PUMP. THE RECALL BEGAN ON FEBRUARY 8, 2005. OWNERS SHOULD CONTACT VOLKSWAGEN AT 1-800-822-8987.


http://www.autosite.com/content/own/service/index.cfm/action/RecallsView/seriesid/38668
 

BioDiesel

Veteran Member
Joined
Oct 29, 2001
Location
CT
TDI
'98 Jetta
"...and the dealership told me that biodiesel eats through..."

Odd the stealership didn't mention the recall. ;-)
They rarely disappoint.
 

Geomorph

Veteran Member
Joined
Oct 17, 2007
Location
Sacramento, CA
TDI
2005 Golf and 2002 NB
Thanks for the info. I checked with the VW customer care number and found out that my car did have this recall and that the work was already done for the previous owner. I suspected this anyway since all the hose clamps on the fuel pump I just got replaced were nice screw tightening ones instead of those spring clamps that come stock. So the one that was on there should have been good.
 

runonbeer

Maintenance EnthusiastVendor
Joined
Apr 15, 2002
Location
Austin, TX/Chapel Hill, NC
TDI
'00 Golf 02M, '10 Golf 02E, '02 UTE 02M
I'd estimate that one out of every five ALH cars that come to me have slow to moderate oil leaks at the vacuum pump. This pump is located in roughly the same position as the PD tandem pump. This part was never recalled. Sometimes replacing the o-ring does not affect the leak. I've replaced my vacuum pump seal about 3 times, and I even replaced the pump. It still leaks. I don't know why.

In 9000 miles you have not exposed that pump to enough fuel to have any affect on the material of the part. I predict that your pump will leak no matter what fuel you use.

Biodiesel does cause degradation of certain materials especially in high heat or heavy sunlight conditions. It makes hoses and o-rings gooey and squishy. I invite you to take the pump apart and determine if any of the seals have become gooey and/or squishy. Most of the time when I come across a leaking fuel line or seal it is very hard and crispy; to the point that it has flattened under the compression of the two parts it intends to seal. You can literally snap it in half as you would a pencil lead. Perform a search on "ULSD shrinkage" if you'd like to learn more. People are now blaming our new low sulfur content diesel fuel for ALH pump seal failures across the country when in reality the seals are simply failing because they are seals. That’s what they do eventually.

The TDI engine is not infallible.
 

Geomorph

Veteran Member
Joined
Oct 17, 2007
Location
Sacramento, CA
TDI
2005 Golf and 2002 NB
I appreciate the information and I looked up the ULSD shrinkage. I don't know how comfortable I feel with your prediction that the pump will leak no matter what fuel I use. I have lived with oil leaks in the past on cars but fuel leaks seem more dangerous. Isn't that why they had the recall? At what point should I be concerned about a fuel leak? Also, why do biodiesel advocates always say that newer diesel cars (newer than '93 or '96, I think) are compatible with biodiesel with no modifications and dealership mechanics always say that biodiesel will eat through all seals and hoses?
 

BioDiesel

Veteran Member
Joined
Oct 29, 2001
Location
CT
TDI
'98 Jetta
"Also, why do biodiesel advocates always say that newer diesel cars (newer than '93 or '96, I think) are compatible with biodiesel with no modifications and dealership mechanics always say that biodiesel will eat through all seals and hoses?"

Both groups aren't 100% accurate.
We don't know for sure all '96+ fuel components are bd compatible.
The inter injector lines certainly are not.

The mechanics overstate far more. Most of the fuel line and seals are bd compatible. Thats been proven over time. But we never gotten a complete parts list of fuel components and corresponding bd comp. confirmation for each.


And the problem isn't as simple as bd compatibility or not.
The seal shrinkage we've seen demonstrates that the transition from one fuel to another can cause problems. But a system can run either fuel exclusively w/o problems. If LSD is used exclusively, no problems. If bd or SVO is used exclusively, you won't get seal shrinkage.

And as runonbeer points out, age and heat and other factors can deteriorate a seal.
 

Geomorph

Veteran Member
Joined
Oct 17, 2007
Location
Sacramento, CA
TDI
2005 Golf and 2002 NB
Thanks for the replies. After thinking this over for a while and spending too much time looking through other threads, I think I may just stick to low Bio blends for now (i.e. B5). The new fuel pump I got has a 12,000 or 12 month warranty. Also the heat factor concerns me as I would imagine that the temperature of the fuel returning from the engine through the pump is quite high and therefore it would make sense for this part to be the most sensitive to biodiesel.
 

Chasee

Self-Exiled SPV, Deactivated Account
Joined
Mar 31, 2004
I thought the return fuel does not go through the pump again, but just back to the tank, allowing it to cool substantially. Am I wrong on this?

Also, on PDs, there is actually a radiator under the passenger side for the return fuel which allows it to cool even more before getting back to tank.
 
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