Main bearing set 320/09203 JCB Dieselmax +0.25 mm, genuine

For the JCB Dieselmax 444 and 448 engines: main bearing set 320/09203, +0.25 mm, a genuine JCB part.

The crankshaft is carried on five main journals, with a pair of shells working on each. A tang or lock on the back stops the shell turning in its housing; the lock position differs between engine versions, so the set is chosen to suit the engine. Poor oil, lubrication faults and long periods of overload wear the bearings quickly. Replacement usually goes together with measuring the crankshaft and renewing the big-end bearings. The shell size is marked on the back of each shell, showing standard or the undersize value.

Specifications

Compatibility

The part is listed for JCB 3CX and 4CX backhoe loaders and JS excavators. The undersize set is for a crankshaft reground by 0.25 mm; the lock is in the middle of the upper shell. The catalogue also has the aftermarket version of this part. Other parts are in JCB Dieselmax engine.

Fitting

Before fitting, wipe the housings and journals with a lint-free cloth: a single speck of dust can mark a bearing. Fit the caps by their numbers and the right way round, and tighten the bolts in stages. Priming the oil system before the first start protects the bearings from a dry start.