[s-cars] Re: Lifter Noise

[William Noland]

Found this writeup, that I'd saved re noisy lifters. The "air bleed" 
method discussed below might be worth a try. Won't annoy the neighbors 
as much as the ATF approach (which produces huge clouds of smoke and 
kills all mosquitoes in a 10 block radius).

There are two main causes of noisy lifter operation. These are dirty 
motor oil and air in the oiling system;

Dirty Motor Oil
Due to the severe operating conditions, and fine internal tolerances, 
the hydraulic lifter/ lash adjuster is very sensitive to dirt or grit 
contained within the oil.
If dirt or grit is present to the lifter’s internal oil metering valve, 
the oil will not flow properly into the high pressure chamber, and noise 
will be apparent.
Use of dirty oil may result in sticking between the lifter’s plunger and 
body, rendering the lifter useless and noisy.

Air
Perhaps the single major cause of noisy lifter problems, and poor engine 
operation! When air is present within the oiling system and lifter, the 
lifter cannot maintain the desired performance. This is due to air being 
a compressible substance. With air present, the lifter plunger will sink 
at an incorrect rate under load, causing failure of the valve event 
(opening).

Air can become present in the oiling system for several reasons;

1. Low oil level, allowing air to be sucked into the oil pan pick up.
2. Cracked pick up tube or pipe, sucking air.
3. Too much oil in the crankcase – this leads to the oil becoming 
aerated and injected into the lash adjusters.

A simple method to identify if a lifter is properly filled with oil is 
to push down on the plunger by hand. If the plunger pushes down there is 
air inside the lifter, remembering that air is compressible. If the 
plunger is solid, only oil fills the internal chamber.

If there is air in the oiling system, which has resulted in noisy lifter 
operation, there is the possibility to bleed this through without having 
to remove the lifters from the engine. A suggested method is:

At normal engine operating temperature, with clean oil installed (and at 
the correct level), gradually open the throttle to approx 3000rpm over a 
15 second interval, then snap the engine back to idle and leave at idle 
for another 15 second interval. Repeat this cycle 10-30 times while the 
vehicle is at “no load” conditions.

If the lifter noise has ceased after these cycles have been completed, 
chances are the lifters are now bled and operating as desired. It is 
still advised to perform the bleeding cycle about 5 more times, then 
allow the engine to idle for a further 3 minutes to ensure the noise 
does not return.
If after performing these cycles, the noise is still present, the 
lifters will need to be removed, cleaned and replaced as necessary, with 
checks also made on the oil delivery system and passages.


Bill Noland