Cummins 4BT parts

The 4BT 3.9 is the four-cylinder member of the B series and the smallest engine we catalogue in volume. Under a generator it covers the small standby band, and in the region it also appears widely in pumps, small plant, light commercial vehicles and a great many repower installations where a 4BT has been fitted into something it did not leave the factory in.

That last category is worth flagging, because it affects how you order. Repowered 4BT installations frequently mix components from several source applications — a vehicle engine with an industrial cooling package, or a genset block with vehicle ancillaries. On those units the engine dataplate tells you less than usual, and photographs of the actual component being replaced are worth more than any part number in a manual.

The 161 numbers on this page cover the 4BT 3.9 across genset and industrial duty. Parts availability is good and prices are low relative to the larger families, which means the practical constraint on a 4BT order is usually shipping rather than the parts themselves. For small orders it is often worth consolidating several sets' worth of consumables into one shipment rather than paying freight on each.

For a quotation, send the engine serial number and tell us what the engine is installed in. On a repower, photographs of the part you are replacing and its mounting will resolve most of the ambiguity faster than any number will.