The 16V F-series engines all run hydraulic tappets. What this means is (in theory) that there is no manual adjustment as the oil should keep the tappets at 'zero lash' all the time.
This means the tappets are in contact with the cam lobe at all times, thus in theory there is no noise and less wear.
The head has oil galleries to each tappet bucket hole, this oil is what takes up the free play inside the tappet keeping it in constant contact.
While oil is indeed a wonderful thing there are several shortcomings. It ages and breaks down, it changes viscosity with temperature, and it carbonises and it turns to a tar-like material.
The tolerances in the tappets are very small, as are the passageways for the oil to move in and out.
Oil clogs these passageways and thus prevents the tappets from operating as they should.
So how do you get them working as they should again? Well there are a few ways. Buy a nice new set at well over £100, clean them out, or there's the best method where prevention is better than cure, which means change the oil and filter frequently an use a quality oil!
If you're reading this you either have a general interest in this or you know how to remove the cams etc. to get to them so I will not tell you how to do that.
This is the tappet bucket itself, this is the part the cam lobe touches. Its not actually flat on the top, it's ground to a radius. This is done so it rotates in the housing.
This is the side of the tappet, the ridge around the side is to allow oil in. If you look in the ridge, just above the band of light you will see a small hole, this is where oil enters the tappet.
Finally the underside. The part in the middle is free to move up and down, if it's just been pulled out of an engine pushing it in will squirt oil out the hole in the side! The shiny circle in the middle is where it pressues the valve stem.
You need to pop that central bit out, to do this bang it hard on a wooden surface, it will pop out after 2 or 3 whacks.
This picture shows the bucket without the central plunger in it. You will more than likely find it's full of old sludgy oil. Use carb cleaner to remove this. It has to be spotless. The shiny ring inside in the bottom is where the central plunger presses against.
This is the plunger removed, side view obviously. The left side presses the valve stem, the right presses against the inside of the tappet bucket.
This is the top of the plunger, the bit that's inside the tappet body. The silver bit in the centre is a ball bearing. This acts as a 1-way valve to allow oil in but not out. There is a small spring which acts against the ball. The oil that goes in bleeds off through the sides of the sliding part of the plunger. This becomes clearer in the next 2 pics after this one.
This is the tappet plunger uncompressed.....
.....and this is it compressed.
This is how the tappets take up the clearence. There is another spring in the plunger to keep the tappet at full extension and allow it to work properly. It should not flop about, if so it's collapsed.
Anyway you need to clean the plunger's internals out, this is not easy. Carb cleaner with the straw pressing against the ball-bearing is good, as is activating it in a tub of petrol/spirits/meths.
When you have them clean, you then should prime them. Put the plungers in fresh oil and activate them. This will get nice fresh oil inside them, so time for them to fill is minimal.
Then simply push the plunger back into its bucket, then put the buckets in a tub of oil and work the plunger in and out again.
You can never use enough oil! Remember that!
With regard to collapsed lifters - this basically means the springs within the plunger have broken. This can be through overheating or an over rev. Ultimately this means you need a new tappet. Sometimes though it can sound like a lifter has collapsed but it's the small spring that acts against the ball bearing has clogged up and stuck closed. Carb cleaner may get it working as it should again.
Linear Mode
