How To Service a RB25 Oil Pump

How To Service a RB25 Oil Pump


There can be many reasons as to why you need this How To article, whether you are simply servicing your own RB25DET or planning on swapping in one. Some may think this job is daunting but in fact it’s a fairly simple process that we’ll be showing you the step by step process on.

Our How To service a RB25 oil pump guide assumes you have already removed the front of your motor, and have the RB25 oil pump removed and ready. If you do not have the oil pump off the motor yet, please refer to our How To Rebuild Your RB25DET article here or our RB25 Head Gasket Tutorial here.

Begin by removing the RB25 front main oil seal using a flat head screwdriver. Make sure you do not scratch or otherwise contact the surface of the housing, or you’ll have a leak that won’t be going away.

Place the oil pump in a vice to secure it, do not clamp on any surface of the oil pump that mates with the engine. Use thick shop rags to protect the outer cuff or the aluminum that protrudes on the outer surface of the oil pump housing.


What you will need to remove the backhalf of your RB25DET oil pump is an impact screwdriver. Use the impact screwdriver to remove the screws that hold the fastening plate in place.


Use the impact screwdriver to remove the screws that hold the fastening plate in place. Make sure your shop rags are secure and that they are protecting the oil pump from damage, not cutting or biting into it.


With all the place screws removed, you can now remove the oil pump cover.


Remove the inner and outer impeller rotors carefully.


Inspect the rings and the outer housing of the RB25 oil pump for any unusual wear or scarring. Next remove the oil pump plug and check the spring and valve, clean both thoroughly. If you see any abnormal wear, it’s best to replace your RB25DET oil pump with a new one or opt for a high performance N1 version.

The part number you are looking for here is a NISSAN 15010-5L800 if you own a NEO version of the RB25 and part number 15010-05U12 for the non-NEO RB25DET.

Next in our how to service a RB25 Oil Pump tutorial, you will be replacing the inner and outer rotors and using a feeler gauge to measure the clearances in the RB25 oil pump. Should any of these values be out of range for your oil pump, it’s time to replace it.


Measure the outer rotor to the inner rotor chip clearance which should be within 0.11 -0.2 mm. Next you will be measuring the outer rotor to the oil pump housing for a clearance range of 0.05-0.09mm.



Use the following diagram to reference where you should be measuring between the rotors for the two steps outlined above.


Now use a micrometer to measure the diameter of the our pump inner ring inlow, which is the groove that protrudes from the back of the inner ring. This ring should be able to spin freely in the micrometer without any signs of warpage. This ring should measure between 0.045-0.091 mm.

Lastly, check the flatness of your rotors with a straight edge and the finest feeler gauge you have. The rotors must be completely flat and without any warpage so test it across many areas of the surface.


If any of these values are incorrect, it’s time to put your oil pump out to pasture and replace it.

What did you think of our how to service a RB25 oil pump guide? Do you have any questions we could help you with? Leave them for us below!