Is there a way to test an oil pump?

[psimet]

Ended up with an oil pump that could have been rebuilt or not. I have no history on it. I would like to test it to make sure it at least pumps some oil before throwing it into a new engine.

I was hoping there was a known easy way to just adapt like a drill motor to the oil pump shaft so I could put it in a pan with oil and test it or something. After searching here I could not find any technique to test oil pumps outside of the engine came up.

Is there an easy way to do it that anyone would like to share?

[Jim/GA]

Yes. Connect to an electric drill. Dunk the body in a bucket of oil. Start running the drill slowly counter-clockwise and be prepared for a mess.

You can also just open the pump and look at the parts that wear. If it was rebuilt, they will be obviously new and good. If it has not been rebuilt, you will see the wear and feel the slop of the shafts in the bushings.

A stock Model A engine does not need or expect very high pressure, just volume, so if the pump is putting out a good volume, the engine will be happy.

[rotorwrench]

The pump design is a positive displacement type with no form of pressure regulation so as long as the gears fit well in the body and the seal plate is still smooth with little wear, then it will put out the basic flow rate it was designed to. Problems I have encountered were cracks in the body (the cast ones like to crack), and a leaky cross drill plug. This stuff becomes evident during visual tear down inspection. If all looks good then it will be good enough. It basically just fills the valve chamber floor with oil so it can feed down to the cam and main bearings unless the engine is modified for pressure oiling. The rods are dippers so they get fed even if the pump is low on output.

Make sure the screen is clean at reassembly and it will be good to go. I test them with clean cleaning solvent in the solvent tank so it doesn't make a big mess that way. I test before final reassembly and then lube them with motor oil during assembly. Put it in a clean plastic bag until it's reinstalled in the engine.

[psimet]

Had to pull the bottom plate as there was a spring on it and my oil pan is a 28 with cleanout so the spring is on the clean out plate instead. Everything looked good. A product I sell for my business comes in an 8oz jar that seemed perfect for the job.

Filled the jar with clean oil, put a slotted bit in the drill as the 3/8” chuck wouldn’t grab the drive shaft of the pump. Slow speed counter clockwise while holding it all in my oil catch pan and viola. She pumps.

Sharing back here in case anyone goes looking in the future.

[Fullraceflathead]

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Great idea!