Can I Rebuild My Eaton Pump

Rebuilding a Ford/Eaton pump unit is seldom an easy thing to do. Before you consider or attempt a rebuild, there are some problem areas you should be aware of. This first part is not designed to scare you off from attempting your own rebuild (well, maybe just a little), but to show you what you may encounter along the way. We have done many Eaton pump rebuilds and see these problems on almost a daily basis. These are the things not mentioned in any instruction sheet or shop manual.

The heart of the Eaton Pump is the actual pumping parts. These pieces must be inspected because they can be unfit for many reasons. The Rollers (of which there are six) have a hard chrome finish. Often this finish has worn through and the metal underneath is exposed. The Roller will no longer be smooth or round. This will require replacement. The inside surface of the Cam Ring will wear to the point that compression inside the pump becomes weak at low engine speeds. The surface can also be scored by the worn Rollers.
It is possible to install the Cam Ring into the Front Housing upside down. This will damage the small pin that keeps it from spinning, shedding metal into the pump mechanism. The Cam Ring will not seat properly and can lock up the pump or deform the Cam Ring. This will cause the Rotor to be damaged during operation. If loose metal gets to the sides of the Rotor, the surfaces of the Housings themselves can be scored and damaged.

The most common damage in an Eaton Pump is to the seal surface of the Input Shaft. The Front Seal can become hard and wear grooves into the shaft surface. Moisture tends to collect around the seal and can cause pitting of the shaft.
Rarely, the pump can be run low on fluid and the Input Shaft will seize in one of the bushings of the pump, usually the rear bushing.
The bolt that retains the Pulley onto the Input Shaft is a high grade bolt. Often this bolt is replaced with an inferior quality bolt which is over-tightened, causing the bolt to break off inside the Input Shaft.

The Rotor is positioned on the Input Shaft using a round key with pointed ends. Even with new parts, the fit is quite loose. Due to the normal pulsing action of pump operation, the Rotor rocks back and forth against this key, causing ridges to form in it and flatten. If the key is damaged to the point that the Rotor fits very loosely on the Input Shaft, the key should be replaced.

The Eaton "roller" style pump is a very simple design. It was used by many car manufacturers from the early 1950's and into the early 1970's. Although Ford stopped using the Eaton on passenger cars with the 1965 model year, it was used on Broncos for several more years and was used for many more years on big Ford commercial trucks. It is also a commonly used pump on tractors, farm equipment and industrial applications.

Even though it is simple in design, there are several small pieces inside that are easily lost or damaged if you are not aware of their location and installation. A few pieces are easily installed upside-down, which is not readily apparent but can radically affect the assembly of the pump and its operation.

You cannot always rely on the plan to reassemble the pump based on the way it was assembled when you took it down. Many pumps have already been improperly assembled by a previous owner or mechanic, even sometimes professional rebuilders. Depending on the brand and distributor of the rebuild kit you buy, the included instructions (if any) are likely to be fair to worthless. Even the instructions and illustrations found in factory Ford shop manuals have mistakes and inaccurate information. Sometimes the information given will not even work on the year and model pump the book claims to cover. The most important thing to remember is that typical kit and shop manual instructions were originally designed for mechanics that worked on these pumps during a warranty period or reasonable time span from when the car was new. They do not address the problems and situations that can come up on rebuilding a 25-30 year old pump that may or may not be complete, original or in rebuildable shape.

Eaton pumps have not been made for many years, so now most of them have many miles on the and have gone through several rebuilds. Unfortunately, the bronze shaft bushings in the pump were never available separately and are never replaced during a standard rebuild. This causes a common problem in that the Input Shaft is so loose in the bushings, and has so much play and wobble, that the front seal cannot compensate for shaft movement and will leak. Usually, the only way to fix this problem is to replace the pump housings with pieces that have bushings in better condition.

The front bushing not only wears over a period of time, but it tends to become "egg-shaped" due to the constant pulling in one direction of the input shaft by the drive belt. This causes the bearing to much looser in one area than others, and the shaft will wobble around enough to overcome the flexibility of the seal.

If you can rebuild your own Eaton pump depends on the condition of your pump, how you remove it from the car, how good of a rebuild kit you are using, and how good the instructions are, if any. Any one of these items can cause you trouble and many pumps have more than one of these problems during a rebuild. The biggest problem is - you don't know what condition your parts are really in until you remove the assembly from the car, tear it down and inspect it. By that time you are into it pretty deep and will have to decide whether to continue on your own or turn it over to a professional.

If you are in the middle of a rebuild, or are thinking of doing one on your own, we will be glad to help you as best we can. Because we are busy rebuilding during the day, we cannot always help you by phone. But if you send us an email with a description of your problem, we will try and get back to you within 24 hours.

Also keep in mind that other than the seals and gaskets that come with a standard rebuild kit, none of the other parts are readily available new. Damaged parts will have to be replaced with good-condition used originals.