1955 Ford Part 101: Repairing the Y Block Oil Pump

If you have been following the build of the 55 Ford Fairlane since the beginning you may have read the title of this post and thought, "Could an oil pump go bad so soon? I thought the Hot Rod Reverend installed that thing in 2015 just before he put the engine in the car!"


And you would be right. Back then, I did replace the oil pump (although the engine only had a few hundred miles on it since it was rebuilt) with an aftermarket unit. You can look back at Post #6 to see that I did install a brand new pump. Many uninformed Y Block owners do not know that Ford did indeed manufacture two separate styles of oil pumps although they both bolt up the same way, use the same drive shaft, etc. The one exception to all of this would be the early EBU 239's that had the tang drive (and matching distributor). Later EBV 239's and all other Y Blocks had the hex drive. But there were two different types of gears. The first, and probably the one most prevalent, would be the spur gear.

FoMoCo parts book diagram of a spur gear oil pump


Spur gear oil pump cover (note the bump out on the cover plate)


The second would be what was called the gerotor drive. You can tell by the diagram below that it is obviously a "rotary" style of drive whereas the spur gear was simply two large cogs creating the pressure needed to push the oil through the engine. Whereas Ford's spur gear oil pump castings were all cast iron, it seems that the engineers and bean counters decided to go with cast aluminum for the gerotor style. However, the pump I installed on the 55 Ford six years ago was cast iron - a unit from an aftermarket company that had copied Ford's original aluminum castings and sold the cast iron pumps to the general public back in the 60's.

FoMoCo parts book diagram of the gerotor gear oil pump


Both oil pump versions put out an ample supply of oil and operationally provide a fair amount of pressure. However, the gerotor style is not as prone to cavitation (creating erratic drops in oil pressure) under sustained high rpm of the engine. Whether or not Ford came up with this in 1957 at about the same time that Ford and Mercury Y Blocks were dominating the Nascar tracks still remains a mystery to me. Suffice to say, there was no problem with oil delivery or oil pressure concerning my oil pump. The reason for removal and inspection concerned a very small leak from the pump cover and what seemed to be a little bit of seepage near the block.

For some reason I had forgotten that the housing was cast iron (most of the gerotor pumps are aluminum housings) so I made the mistake of posting the above two pictures on social media along with a question, "Does anyone know when Ford made a cast iron gerotor pump? I thought they were all aluminum." Then the circus took place as different people all weighed in - some said things like, "I've been working on Y blocks since the 70's and own about 30 - Ford never made an aluminum housing pump, they are all cast iron." Still other uninformed people stated, "What is a gerotor oil pump? Been around Y blocks all my life and I've never heard of such a thing!" It really was a "pass the popcorn" moment! Some of the veterans in the Y Block group weighed in to back me up, but the ignorance among the know-it-all's persisted. At times, I really think social media does the classic car hobby a huge disservice because the myths and the misinformation proliferate. Even when you post documentation, pictures, or diagrams from Ford's manuals people still persist in relaying incorrect data. It becomes a real turn-off for the younger crowd who is trying to carry on the hobby and maintain a classic car or truck. Ok, let's get back to the task at hand...


Like I had suspected, the large O-ring that seals the flat cover plate to the housing was not doing its job to keep the oil from leaking! Since there are two styles of oil pumps, and since there is some confusion over Y blocks (even the location of the keeper washer on the oil pump drive shaft), I decided to make a video of removal, repair, and installation. Included are such helpful items as the tools you will need, the procedure from the shop manual, etc. During the video, I even reviewed the contents of a rebuild kit should you decide to rebuild your own gerotor pump. The video is quite thorough, and since it is right around 25 minutes you may want to pop yourself some popcorn, pull up a seat, and enjoy the show!


Video: 292 Ford Gerotor Oil Pump Repair


The Hot Rod Reverend

aka Daniel Jessup

© 2021 by Daniel Jessup