It’s easy to think ‘she’ll be right’ and hope that the lifters will bleed down themselves. However, leaving it to chance can be an expensive mistake to make.
All Head Services have had numerous occasions where a customer has fitted a cylinder head that has bucket style hydraulic lash adjusters, only for them to call with an issue. The engine either fails to start due to lack of compression or even worse, the cylinder head having to be removed and sent back with bent valves!
Many engines, such as the Holden Astra X20XE and X18XE and the Nissan Patrol RD28, use bucket style hydraulic lifters. These lifters are not supplied with exchange cylinder heads and are generally swapped over from the original cylinder head by the technician prior to fitting the exchange head.
The lifters are usually still full of the original oil and as such become like a solid lifter and if not bled prior to fitting.
There is a significant chance that the lifters will hold the valves open resulting in no compression or worse still the valves being bent due to vale to piston interference. This results in an expensive rework, cost to the workshop and inconvenience to the customer.
The following simple steps show how to bleed the hydraulic lifters and ensure that this issue does not occur in your workshop: (Note: Each of the lifters must be bled the same way)
- Set the lifter in a vice with soft jaws fitted and the oil hole facing down.
- Use a socket extension or a suitable bolt to push on the lifter plunger.
- Operate the vice to gently squeeze the lifter plunger in and out to remove any oil.
- Continue to squeeze the plunger in and out until you can feel with your hand that there is approximately 2-3mm of movement under slight spring pressure.
While this procedure might seem a bit tedious, it’s worthwhile to ensure that there are no issues with the lifters holding the valves open.