Inlet valve seat insert 320/02691 JCB Dieselmax, genuine

For the JCB Dieselmax 444 engine: inlet valve seat insert 320/02691, a genuine JCB part. The card also lists 320/A2553.

Inlet and exhaust seats differ in diameter and material; the seat is chosen for the valve type. A new seat is cut on the same axis as the guide and the valve is lapped in. Valve recession is compared with the limit in the service manual. The seat carries heat from the valve head into the cylinder head, so a tight fit matters for valve cooling. A loose insert can drop into the cylinder and cause serious damage. The Dieselmax has two inlet and two exhaust valves per cylinder.

Specifications

Compatibility

The part is listed for JCB 3CX and 4CX backhoe loaders. The catalogue also has the aftermarket version of this part. Other parts are in JCB Dieselmax engine.

Fitting

Remove the old insert without damaging the head; the new one is usually chilled and pressed in. Then cut the seat face, lap the valve and check the seal. This is engine shop work. Measure the bore in the head; if the insert fits loosely, a new one is not fitted without machining the head. Check the valve guide before cutting the seat.