Pushrods and Lifter Bleed Down
Seasoned HDF Member
Joined: Aug 2017
Posts: 7,323
Likes: 11,758
From: Omaha,NE
There's a lot of misinformation here. Whoa.
To answer your question, used lifters have oil trapped in the plunger from normal use, or if new, from factory testing. The plunger must be compressed to expel that oil. This occurs AFTER your pushrods are adjusted. Procedure as follows:
To answer your question, used lifters have oil trapped in the plunger from normal use, or if new, from factory testing. The plunger must be compressed to expel that oil. This occurs AFTER your pushrods are adjusted. Procedure as follows:
- Both lifters for the cylinder you're working on are on base circle of cam (lowest position).
- Adjust pushrods to zero lash (no up and down movement; no tighter, nor looser than exactly zero lash.
- This next bit depends on the brand of pushrod, but adjust your pushrods 3 full turns for stock lifters, or 4 for Wood lifters (check your pushrod instructions).
- Now WAIT. Do not turn over the engine until you can spin the pushrods freely with your fingers. That ensures that they are sufficiently bled down before turning the engine over to work on the next cylinder. Failure to do this could result in valve overtravel and piston-to-valve contact. Bad.
- Repeat procedure for next cylinder.
Last edited by strych9; Oct 2, 2018 at 09:34 PM.
Stage III
Joined: Aug 2017
Posts: 3
Likes: 0
From: Youngstown, Oho
HARLEY PUSHROD ADJUST TAPPET
DRY HYDRAULIC UNIT
Using a large paper clip, insert into hydraulic unit plunger end and pump down on piston to expel oil in unit.
With hydraulic unit dry (no oil in piston) set tappet at its LOWEST POSITION before inserting dry hydraulic unit. (If you leave the unit in it will refill with oil and you will have to pump out the oil again).
Install push rod and turn adjusting screw downward until hydraulic unit piston bottom in its bore.
Turn adjusting screw upward exactly 1 -3/4 turns.
Lock adjustment by tightening locknut to 10 ft-lbs torque.
When using this method Bleed Down is not required before proceeding to next tappet.
Continue for each pushrod in like manner.
Note: Do not leave other hydraulic units in tappet as they will fill with oil and need to be re-bled.
WET HYDRAULIC UNIT
With tappet in its lowest position loosen locknut and turn adjusting screw upward, shortening push rod until push rod has noticeable shake.
Keep push rod from turning by holding with wrench on flats at base of push rod.
Slowly turn adjusting screw downward, lengthening rod, until all shake has been taken up.
Mark adjusting screw with chalk and turn it down exactly four full turns.
Lock adjustment by tightening lock-nut to 10 ft-lbs torque.
Be sure to allow hydraulic unit to bleed down before turning engine over to adjust next tappet.
Usually, hydraulic unit will bleed down in 5 to 10 minutes.
CAUTION Turning engine over before hydraulic unit bleeds down may cause valve interference resulting in damaged push rods or valves.
When push rod can be rotated with finger tips, hydraulic unit has bled down sufficiently and engine may be turned over to adjust next tappet.
DRY HYDRAULIC UNIT
Using a large paper clip, insert into hydraulic unit plunger end and pump down on piston to expel oil in unit.
With hydraulic unit dry (no oil in piston) set tappet at its LOWEST POSITION before inserting dry hydraulic unit. (If you leave the unit in it will refill with oil and you will have to pump out the oil again).
Install push rod and turn adjusting screw downward until hydraulic unit piston bottom in its bore.
Turn adjusting screw upward exactly 1 -3/4 turns.
Lock adjustment by tightening locknut to 10 ft-lbs torque.
When using this method Bleed Down is not required before proceeding to next tappet.
Continue for each pushrod in like manner.
Note: Do not leave other hydraulic units in tappet as they will fill with oil and need to be re-bled.
WET HYDRAULIC UNIT
With tappet in its lowest position loosen locknut and turn adjusting screw upward, shortening push rod until push rod has noticeable shake.
Keep push rod from turning by holding with wrench on flats at base of push rod.
Slowly turn adjusting screw downward, lengthening rod, until all shake has been taken up.
Mark adjusting screw with chalk and turn it down exactly four full turns.
Lock adjustment by tightening lock-nut to 10 ft-lbs torque.
Be sure to allow hydraulic unit to bleed down before turning engine over to adjust next tappet.
Usually, hydraulic unit will bleed down in 5 to 10 minutes.
CAUTION Turning engine over before hydraulic unit bleeds down may cause valve interference resulting in damaged push rods or valves.
When push rod can be rotated with finger tips, hydraulic unit has bled down sufficiently and engine may be turned over to adjust next tappet.
Last edited by Tornado Jim Belino; May 8, 2019 at 01:04 PM.
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