Nissan RB20 / RB25 / RB26

Nissan's straight-six — the RB20, RB25 and RB26 — in the Skyline, Laurel and Cefiro, and in the Maxima and 300ZX in some markets.

The RB26DETT is the GT-R's engine and is the reason most people arrive at this family, but it is a small fraction of the RBs on the road — and almost nothing written about it applies to an RB20DET in a saloon.

⚑ Establish which RB is fitted before anything else. These are among the most swapped engines in existence, and a car's badge is not evidence. The code is cast into the block.

On a standard engine the recurring items are age. The crank angle sensor in the cam-driven distributor housing fails with heat and gives an intermittent cut-out; the ignitor and coil packs are a known set; and the plenum and inlet gaskets leak, giving a lean idle that reads as a fuelling fault.

Oil control is the family's genuine engineering limit, and it is the reason the aftermarket sells restrictors and sumps. On a standard road car it is not the problem; on a modified one it is the first thing to design for rather than the last.

Parts for the RB26 are made; parts for the others increasingly are not, which is often what decides a repair.