Leaky pumps
Due to recent discussions of injection pump seal failures on some of the biodiesel forums. We decided to run an article that Rachel wrote for BiodieselSmarter magazine a few months ago.
Dear Wrenchwench,
My wife and I have just experienced an injection pump seal failure at 70k miles in our 2003 Golf. In perusing the TDI forums it looks like this is becoming a common failure in cars that go from high concentrations of biodiesel to ULSD fuel if they have a history of LSD before. We have been using from our local coop for the past year or so. After ULSD became available and my wife began to use it in the car when it was cold or bio wasn’t available, she began to notice that her car was hard to start. If she parked on a downhill slope, it was less likely to be a problem but after a month or two it finally gave up. After a tow to VW this week, they confirmed a leaky pump leading to a vacuum loss on the fuel line. I had it towed to a local mechanic/friend who will rebuild the pump for us. Have you heard of any other people using biodiesel and ULSD have these problems?
Signed,
Leaky Pump
Dear Leaky Pump,
Yes, It seems like this question is popping more and more. We first started hearing more about injection pumps leaks after last summers Elsbett SVO
(straight vegetable oil ) conversion workshop in Pittsboro, NC. After last years workshop we had three reported injection pump leaks. Two of the reported leaks were TDIs and the other was a 1.6 turbo diesel with the mechanical pump.
One of our Elsbett workshop participants researched the issue further and spear-headed a series a injection pump seal replacements on the two TDI vehicles.
What was found was that the leaks tend to occur more often on vehicles where the owner switches between biodiesel or vegetable oil and petroleum based diesel fuel. It is interesting to note that more incidents of pump leaks have occurred in conjunction with the new ultra low sulfur diesel requirement to change from 500 ppm to 15ppm. In 1993, the sulfur levels were reduced from 5000ppm to 500ppm and there was some issues with leaking fuel seals and o-rings. Chevron and other petroleum refiners have released statements about the new ULSD and fuel seal leaks; They claim that if you do experience a leak it is not due to the reduction in sulfur levels: Past experience indicates that the common denominator is expected to be nitrile rubber (Buna N) seals that have seen long service at high temperatures. High temperatures have a tendency to accelerate seal aging. If you are using biodiesel, specifically, high percentage blends then Buna N/nitrile rubber seals are not compliant and can be a point of concern. If you are working on replacing the seals in your injection pump I would look to these two resources:
1. Diesel Fuel Injection Service
8922 NE Vancouver Way
Portland, OR 97211
503-285-1213
503-235-1947
888-285-1213
I purchased a bosch viton seal kit from these people this year for my 1989 Dodge pickup.
They were very helpful and knowledgeable. They also rebuild pumps too.
2. www.dieselgeek.com has a comprehensive to-do article on Injection Pump Head Seal Replacement Procedure for 1996-2003 TDI engines
http://www.dieselgeek.com/TDI_Injection_Pump_Head_Seal_Replacement.htm
Original post by Rachel