What are Tappets?

[CALSHOT]

A couple of folks have mentioned tappets in different posts, mainly the ones to do with the death rattle.

What are tappets? and if they're loud is that a problem?

[Dan_Q]

tappetts are what links your camshaft to your valves. If the clearance is incorrect (usually cased though a combination of tappet / cam / valvetip wear) then it will make a louder "tapping" noise in the top end than usual.

not sure what car you have but all FWD / 4WD celicas have solid lifters, which cannot be adjusted they can only be replaced, which can be an expensive job if you don't know how to do it yourself.

my old 1600 i just remove 5 bolts, take a cover off, and adjust them with a screwdriver and spanner

[Monkey Boy 1]

I know of at least three types of Tappet that are use on 4 stroke engines.

Calibrated (solid) tappets

Hydraulic Tappets

Bucket & shim type Tappet

This pic is of a hydraulic tappet

As the distance from the top of the valve to the camshaft is constantly changing in an engine due to wear, the tappet sits in between the rotational movement of the camshaft lobe and the axial movement of the valve. Therefore over an engines life, in Theory it's eaier to change tappets than change valves.

On cold mornings on engine start up, you hear much more mechanical top end noise from an engine with Hydraulic tappets as the engine oil is used to "pump up" the tappet to the correct gap.

Bucket and shim type tappets are another alternative, Usually seen on motorcycles as their valvgear is smaller and it's more difficult to produce small hydraulic tappets.

On some engines produced by GM, Mitsubishi & Toyota for example. there is another way of taking up the gap between the valve tip & cam lobe, This is by using a Roller follower & hydraulic lash adjuster.

Without going into too much technobabble may I suggest that you have a look on google for this.