Exhaust valve 320/03698 JCB Dieselmax, genuine

For the JCB Dieselmax 444 engine: exhaust valve 320/03698, a genuine JCB part. The card also lists 320/03616, 320/03521.

Valves are assessed together with their seats during a head rebuild: the valve face and seat are ground or lapped, and the guides are replaced if needed. Stem diameter and length are set by the head, so the valve is chosen by part number. Inlet and exhaust valves are not interchangeable: the exhaust valve is made for higher temperatures. The valve is held by collets and the valve spring: the spring closes it and the rocker opens it through the pushrod. Too small a valve clearance keeps the valve from closing fully so it burns; too large a clearance makes the valve gear tick.

Specifications

Compatibility

The part is listed for JCB 3CX and 4CX backhoe loaders. Unlike the inlet valve, the exhaust valve is made of a material for higher temperatures; the two are not interchangeable. The catalogue also has the aftermarket version of this part. Other parts are in JCB Dieselmax engine.

Fitting

Lap the new valve into its seat with lapping paste and clean off every trace of it. Renew the valve stem seal and refit the springs and collets. After the head is refitted, set the valve clearance to JCB figures.