There are lots of people out there who love to soak their hydraulic lifters. From lubricating the needle bearings to “pumping them up”, everyone who does it seems to have a reason. If you are going to soak your lifters, likely the best reason is “it can’t hurt” (anything other than your wallet, slightly).
Shown above is a section view of a hydraulic flat tappet lifter, but the inside of a hydraulic roller lifter is the same. To “pump up” a lifter, oil has to go from the reservoir inside the plunger (7), past the check ball (4), and into the “high pressure chamber” which is also occupied by the check ball spring (8), check ball retainer (5), and the plunger return spring (9).
Simply soaking a lifter won’t displace air that is within the high pressure chamber. To do this, one can follow either of the following procedures:
Fill and Pump Method:
- Confirm that the lifter feels spongy by depressing pushrod seat (2) with a pushrod or other tool.
- Through the hole in the side of the body, fill the lifter with oil until it comes out of the hole in the center of the pushrod seat (2). This indicates that the reservoir is full
- Using a pushrod or other tool, pump the lifter to draw oil from the reservoir, through the check valve (4), and into the high pressure chamber. Once this is done, the lifter will feel hard. Repeat step 2 and store the lifters with the pushrod seat (2) up until you are ready to install
- Repeat from step 1 if necessary
Vacuum Soak Method
- Confirm that the lifter feels spongy by depressing pushrod seat (2) with a pushrod or other tool.
- In a vacuum chamber, place lifters in a container and submerge in oil.
- Pull a vacuum in the chamber of between 25-30 inHg. Hold vacuum for minimum 10 minutes
- Release pressure
- Repeat step 3. Once this is done, the lifter will feel hard. Store the lifters with the pushrod seat (2) up until you are ready to install
- If lifter is still spongy, return to supplier for further investigation
Conclusion
Using one of the above processes, you can avoid the annoying experience of waiting for your lifters to pump up in your freshly rebuilt engine. Of course, allowing them to pump up on their own in the engine at a speed 2500rpm or below won’t hurt a thing, either.
