Harmonic balancer
It is a device that absorbs and dampens the vibrations produced by the crankshaft, connecting the crankshaft to the engine’s frame. This helps reduce wear and tear on the engine’s components, as well as reduce noise levels and smooth out engine operation. The harmonic balancer also helps keep the timing belt or chain in sync, as it controls the crankshaft’s speed of rotation. The crankshaft does not ride directly on the cast iron block crankshaft supports, but rides on special bearing material. The connecting rods also have bearings inserted between the crankshaft and the connecting rods. The bearing material is a soft alloy of metals that provides a replaceable wear surface and prevents galling between two similar metals. Each bearing is split into halves to allow assembly of the engine. The crankshaft is drilled with oil passages that allow the engine to feed oil to each of the crankshaft bearings and connection rod bearings and up into the connecting rod itself.
The harmonic balancer itself does not control timing. It’s keyed to the crankshaft and only affects timing if:
- The timing tab or the balancer's timing mark is misaligned (e.g., using an incorrect replacement).
- The timing chain is disturbed (which won’t happen just from balancer removal).
removal
Use a proper harmonic balancer puller to avoid damage. Before removal, check where the TDC timing mark on the balancer lines up on your timing tab (note the position for reference). Inspect or clean the keyway on the crankshaft snout and the key itself.
When installing the new balancer, make sure it: Matches the old one in diameter and depth. Has the timing mark in the same position relative to the keyway. Is seated fully using a proper installation tool (do not hammer it on).
After installation: Re-check timing with a timing light once the engine is running, in case the new balancer’s mark is slightly off due to manufacturing differences.