How to Bleed Hydraulic Type 4 Lifters

How to Bleed VW Type 4 Hydraulic Lifters

Properly bench‑bleeding hydraulic valve lifters ensures they are filled with oil and free of air before installation in Type 4 engines (VW Bus, Porsche 914/912E).

Materials

• Hydraulic lifters (cleaned)
• Engine oil
• Bench‑bleeder tool (suitable for VW lifter diameter)
• Small syringe or dropper (optional)
• Clean cloths or towels
• Gloves

Tools

• Bench‑bleeder assembly fixture
• Adjustable wrench or pliers (for tool assembly)
• Small brush (for cleaning lifter bores)

Procedure

1. Prep & Inspect
   • Ensure lifters and tool are clean and free of debris.
   • Check lifter bore surfaces for scoring; brush lightly if needed.
2. Assemble Bleeder Tool
   • Mount lifter(s) in the matching socket of the bench‑bleeder fixture.
   • Secure fixture per manufacturer instructions.
3. Fill with Oil
   • Pour engine oil into the fixture reservoir until lifters are submerged.
   • Use a syringe to bring oil up through lifter plunger if necessary.
4. Bleed Air
   • Press and release the tool’s plunger/piston repeatedly.
   • Watch for air bubbles escaping into the reservoir.
   • Continue until no more air bubbles appear.
5. Finalize
   • Top off reservoir to ensure lifters remain filled.
   • Remove lifters carefully—keep oil in place.
   • Wipe off excess oil; install lifters immediately to prevent air intake.

Tool Specifications

Tips & Reminders

• Keep components submerged—air will re-enter if lifters drain.
• Bench‑bleed lifters immediately before engine assembly.
• Dispose of any oil drips and clean work area.

Bonus Tips:

When bench bleeding lifters, using a fry daddy or similar heating device to allow you to carry out the above procedure can help speed up the process. If you can't use warm or hot oil, you can use a lower viscosity engine oil to simplify the process.

Are your Type 4 Hydraulic Lifters Noisy?

The reason why Aircooled Technology does not recommend hydraulic lifters is that they tend to bleed down if you don't drive your car almost daily. That is why all Type 4 Store camshaft kits feature solid lifters.

If you do still run hydraulic lifter and have one or more lifters that won't pump up, here is what Jake has had us do in the past:

1. Remove and replace your oil filter. Do not pre-fill it with oil.
2. Add a bottle of Marvel Mystery Oil to the crankcase.
3. Check oil level to make sure it's above the minimum. It is ok if you run the oil level at full or a tad above. It's only going to be for a short period of time.
4. Take your car out for a drive. Once the engine is warmed up, find somewhere you can run a steady speed and keep your rpms up. Ideally, this should be above 4000 rpm but below redline. Do not exceed 220F oil temp while doing this.
5. While the engine is still hot, drain the oil and then change the filter.
6. Refill the engine with Valvoline Restore and Protect 5w30 (yes, you want a thinner oil).
7. Take the car out and repeat step 4.
8. At this point, the lifters should have all pumped up and be quiet. We would then recommend using a high detergent diesel engine oil with a CI-4 rating for the next oil change interval, like our 106-7177: https://lnengineering.com/15w-40-conventional-heavy-duty-engine-oil-1-gallon.html
9. If they have not pumped up, you can repeat steps 1 though 4, but likely you may need to adjust the valves or pull the lifters to bench bleed them.
10. If you do end up pulling the lifters, using an ultrasonic cleaner is recommended to thoroughly clean the lifters out before bench bleeding them. Ideally, you should put the lifter in a mason jar and fill with Marvel Mystery Oil, then put that sealed container into the ultrasonic.