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STANADYNE Injection Pumps and biofuels

11K views 4 replies 2 participants last post by  Jeffrey Brooks 
#1 ·
I have been doing biofuels research with an old 6.2L diesel engine for four years. My method is blending gasoline with vegetable oil at 20% gasoline/80% Waste Vegetable Oil (WVO).

I find the STANADYNE DB2 Injection Pumps are failing after about 9 months on the above fuel blend. I believe the problem is one or more seals inside the Injector Pump are failing due to the presence of alcohol in my blend, because in regions were alcohol is not blended into the gasoline, bio-blenders do not tend to have failed injector pumps. In my region alcohol is commonly blended into gasoline at 10-20%, which means my bio-blend includes 2-4% alcohol, which is most probably ethyl, but might be methyl alcohol. At that percentage of alcohol there might be a problem with seals.

1) Does anyone here agree with my conclusions?
2) Does anyone know if there is a rebuild kit for the STANADYNE DB2 Injection Pump that can handle biofuels (alcohols)?
3) It would be very useful to my research if I could rebuild these pumps myself, so that I can see what is going wrong with them. So, does anyone know where I can purchase a repair manual and rebuild kit for this pump?
4) Is anyone here experimenting with bio-fuels on a 6.2L/6.5L diesel engine?
 
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#2 ·
It would be nice to know that the rebuild kits for Stanadyne DB2 diesel injector pumps were biodiesel friendly; however, I have found no definite evidence that Stanadyne has modified their rebuild kit, and my persistent problems with failing recently rebuilt Stanadyne DB2 diesel injector pumps tells me that Stanadyne has not modified their rebuild kit.

Since it is now clear to me that Stanadyne does not offer a bio-fuel friendly rebuild kit for their injector pumps. Then, perhaps, we could have a write-in campaign with Stanadyne to force them to offer a bio-fuel friendly rebuild kit for their injector pumps. They would have to replace all silicon and buna seals with Viton or Teflon seals.


Corporate Headquarters

Stanadyne Corporation

92 Deerfield Road

Windsor, CT 06095
USA
Phone: 860-525-0821

Fax: 860-683-4500
 
#3 ·
I believe your assessment of pump failure due to alcohol presence is correct. I would recommend changing your blend of 20% gasoline to 20% D2 or kero to bypass the gas/alcohol problem.

Ever thought of converting that WVO to biodiesel? That would be a lot better on the engine.

Good luck on getting Stanadyne to do anything with these old pumps...
 
#4 ·
Thanks for the comment. It turns out that the amount of alcohol in my blend due to blending with gasoline is not the problem. My most recent IP failure was due to adding a gallon of gear oil to the blend, but not increasing the amount of gasoline to thin it properly. It coked my injectors and killed my IP.

I ran the tank down to E before adding the usual 20 gallons of WVO/gasoline blend on top. The residual previous blend with gear oil in it was still in the fuel lines and made it difficult to start the engine after replacing the injectors and IP. Even after a few days of driving around to equalize the current blend with the residue of the previous blend still did not improve starting, so I ended up increasing the gasoline content to 30%. The engine now starts right up cold and runs fine.
 
#5 ·
So here is an update to this thread. It turns out that every time my injectors and/or injector pump has failed was because immediately before that failure I had experimented with making diesel fuel out of Waste Motor Oil (WMO).

A few weeks ago I began experimenting again with WMO to understand it better. Rumor has it that WMO and WVO are incompatible, so I pumped out my main 30-gallon (120L) fuel tank, then processed 20 gallons (80L) of black diesel into that fuel tank. The engine ran fine for three days, then there was a precipitous loss of power and increase of smoke from the exhaust, and a rash of plugged fuel filters.

That weekend I pulled my injectors and found them coked shut. I replaced those injectors with a set that I had coked up from previous similar experiments and had cleaned in lacquer thinner. I also pumped out the fuel tank and flushed it out with gasoline, then pumped it out, then flushed it out with lacquer thinner, and back-flushed the fuel filters several times, and refiltered the fuel.

The engine ran much better, but has not returned to its former glory, so this weekend I plan to pull the injector pump to see if its internal screen is plugged and/or the pump is toast. I plan to have a replacement injector pump ready.

So, in conclusion, alcohol in the fuel blend had nothing to do with the IP and injector failures, and everything to do with the incompatibility of WMO and WVO. Blending these different oils together produces a precipitate of about 10% of the solution. The precipitate is primarily free carbon solids and liquid lacquers, together they make a rubbery like glue that glues up the injector pump and cokes up the injectors.

So does anyone know where I can purchase a repair kit for a STANADYNE DB2 Injection Pump?
 
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