Restoring a Bosch EFEP 385A

Bringing a Bosch Fuel Injection PUmP Test Bench Back to life

One of the most difficult parts of working with Bosch fuel injection pumps, besides the lack of resources and technical details in the first place, is finding a shop that has the equipment needed to ensure your pump is running efficiently. Anyone can polish it up and replate, but getting a fuel injection pump clean is far different from making sure it's working well.

Not only do we have Bosch test benches, but we're so dedicated to getting our restorations right that we are always on the lookout for better options, even if that means more work on our end.

About a month ago we found a shop looking to unload some less-than-pristine examples that were perfect for our needs

Though rough around the edges, this EFEP 385A was exactly what we were looking for to upgrade our service. Built in December of 1977, it had a lower horsepower, perfect for gasoline fuel injection pumps, was quieter, and didn't require quite as many modifications as our previous benches, meaning we could get it up and running quickly.

After a brief inspection we got the process started. The bench technically ran and the worst issues were cosmetic, but we're a restoration shop and we don't go half-way when it comes to a classic...even a test bench. All the removable parts were disassembled, cleaned, and stripped. The main body was sandblasted and prepped for painting and we had our fabricator get started on the few modifications needed.

Once we got it apart, it was clear that it had never had its fluids changed and had rarely been cleaned (never thoroughly) but despite that, all the important pieces were in remarkably good shape. The fluids all had to be flushed and replaced, which actually took a little research. They had never been changed over the previous decades and even other experts in the field weren't sure exactly what grade to go with (more on that at the bottom).

After some color matching, a few quick coats did the job and this half-century-old bench was looking brand new. A couple hours of assembly had the tubes, cranks, gears, and dials ready for use, and once the wiring was straightened out, it was begging for a fuel injection pump.

Slight modifications included rewiring it to run off a normal wall plug, installing a light bar inside the housing for easier viewing, removing a number of the plunger fittings and adjusting the remaining for a gasoline Bosch fuel injection pump. As mentioned before, we also drained and replaced all the fluids, checked for leaks, and replaced hoses, clamps, and fittings where necessary

And just like that, after some testing we've got a "new" test bench ready to dial in your Bosch fuel injection pump. Like most things fuel injection pump related, it wasn't easy, but like most things that aren't easy, it's rewarding to reach the finish line.

There's nothing quite like seeing a well-done restoration bring a derelict machine back to life. Even more, since we'll be using this machine to fix countless fuel injection pumps in the future, this bench will be breathing life into Pagodas for decades to come.

Replacing the Fluids

The Life-Blood of the Bosch Test BEnch

Ignored and forgotten for over half a century, the fluids coursing through the Bosch test bench are essential to its function. Like the oil in your engine or transmission, out of sight should not be out of mind, and these fluids were in dire need of a refresh.

To make matters even less clear than the fluid we were replacing, no one familiar with the machine (and that's not a lot of people) knew what kind of fluid it took. After vague suggestions and a bit of research we landed on a rust and oxidation inhibited general purpose oil, which, up to this point, has worked flawlessly. In the images you can see the state of the oil when it first came out of the bench on the left, after one flush with clean oil, and the clean oil as it should appear on the far right.

DIRTY

FIRST FLUSH

CLEAN

The Details

YOU GOTTA SHOW OFF YOUR WORK

Take Two: Taking on a Second EFEP 385A

There's No Such Thing
As too many benches

Another day, another bench here at Black Forest. Now that we have our first EFEP 385A and EFEP 390 restored, we're on to our next project with another EFEP 385A. This one was in a little bit rougher shape. Like the previous examples, everything still worked, but there was a bit more wear and tear and a whole lot of rust we had to get through. Not only that but the motor and wiring on this model also needed quite a bit of work in comparison to our previous restorations so we had to go a bit deeper.

The previous benches had some cosmetic issues but the wiring and motor were in good condition and rust was minimal. This bench required getting under the skin, literally. We removed the body, panels, grates and access doors as well as removing the engine and corroded wiring components. Once the rust was removed, the bench got some sanding and a fresh coat of paint while the body required some heavy sanding, grinding and even a bit of bondo work for a few holes and gouges.

Replacing the tubes and wiring on this bench was a big part of the process. Seals were worn out, tubing was deteriorated, and many if not all of the clamps had loosened and sprung small to moderate leaks. In some areas everything needed to be replaced. Others came back to life after cleaning out the lines and contact surfaces.

With the bench running it was time to address the working conditions. Most shops aren't exactly quiet, but it's nice to be able to hear the phone ring. Since we had completely pulled this bench apart we figured we might as well improve the insulation and sound dampening. One box of high-density acoustic foam later and our new bench rivals most recording booths.

Once we got the new fittings, tubes, liquids and clamps replaced and installed it was time to fire it up. Small leaks were cleaned up as needed but, for the most part the bench started and ran smoothly. Take a look at the test video below to see it in action.

Once the insulation was installed all that we had left was a test run and assembly of the dials, gauges, labels, remaining hoses, glass cylinders and hardlines. Since this was our second restoration of a Bosch EFEP 385A, this bench came together smoothly and quickly, and within a day of wrapping up the restoration work, the bench was installed in our pump room with a fuel injection pump mounted and ready for testing.