While working on the boat this fall, I was keeping Ernie, the ’86 diesel Escort, at a friends house. At one point she was needing a car to get near where I was, and I needed a car to get home, so she was going to drive it down. But she didn’t get much past the drive way because the brake light came on, and the brakes had lost power—a scary experience for an unsuspecting sole.
How it works
Most cars use vacuum as a source of power to boost hydraulic actuation of the brakes and other accessories. This car also uses vacuum to advance timing & increase idle for cold-weather starting or when using the AC. However, diesels don’t use active air-restriction (e.g. a butterfly valve) to blend air & fuel (naturally-aspirated diesels are designed to always have maximum air availability, and control engine output by metering the fuel). This means that in order to fit into what would otherwise be a gasoline driven body, a diesel needs another way of generating vacuum. Sometimes it’s mechanical, in Ernie’s case it’s an electronic pump, which draws the less-than-atmospheric pressure.
Issue
So when my friend went to brake and was forced to generate her own hydraulic pressure, I knew right away that it was either a leak in the vacuum system or a faulty pump. After inspecting the system for disconnected hoses and obvious leaks, I used my break bleeding tool, which has a little manual vacuum pump & gauge. No leaks, therefor faulty pump. No problem, I’ll just replace the pump—or so I thought.
Repair
After querying several venues for replacing or rebuilding my existing pump, I learned that Cardone—an aftermarket supplier/rebuilder of many auto pumps & components, has abandoned this pump. I even had one parts supplier say that “if it is on our website, than Cardone will rebuild it rebuilt” who then returned it saying Cardone had declined to rebuild it.
Long and short of it, I needed to find another pump. Looking on google & ebay turned up options in the $300+ range while I was looking to spend no more than half that for new equipment, and significantly less if used. Then I stumbled across a lot-sale that happened to have some little 12v vacuum pumps that fit the bill, so I picked them up. The flow-rate is not as high as the original equipment, but it is capable of drawing as strong a vacuum, so I decided that was a sacrifice I was willing to make.
1. Locate the wires that power the original vacuum pump. They are originally routed through the conduit that runs over the injector lines down between the injection pump & the alternator. I cut the wires on the pump side of the pigtail connector, so I could still disconnect the new pump if I wished.
2. Remove the wires from the conduit enough to be able to run them to a desirable location. I chose to locate it above the transmission, zip-tied to the powersteering lines.
3. Run enough hose to be able to tie into the vacuum system where the old one does—at the metal T in the tubing, which runs along the underside of the radiator/fan, across from the starter.
4. Because I don’t trust the pump’s seals to hold a vacuum overnight, I chose to put a ¼” (the biggest available) vacuum check valve inline.
5. As pictured in the two photos above, it is practical to chaff-protect & zip-tie the hose where appropriate. If including a check-valve, use an adapter and 3/8″ hose to attach the 1/4″ hose to the 3/8″ T under the radiator.
6. If your vacuum-sensing switch is working properly, your pump should turn on/off at about 18-22 inHg. Located under the black plastic shield in the rear of the engine compartment, it is the black-rubber capped dongle that has vacuum hose going in one end and electrical wires coming out the other.
7. Because this pump is a little slower to make vacuum than the stock pump, when it’s colder out I like to let it run for 15-20 seconds after I’m parked for the night. Provided I don’t step on the brakes, this helps to ensure that the vacuum-driven, cold weather timing advance & idle adjustment have full effect for easy starting the next morning.
Parts discussed include; A1/Cardone 64-1501 vacuum pump, replaced by a KNF Neuberger UN86 KTDC vacuum pump. Both 12VDC.
Let me know if there are any questions or thing that need clarification.
