Opel 17DR / 23YD / 23YDT

Opel's older diesels — the 1.7 17D and the 2.3 23YD and turbocharged 23YDT — in the Kadett, Astra, Rekord and Omega.

These are indirect-injection engines with mechanical pumps and nothing electronic worth the name: no rail, no filter, nothing to regenerate, and nothing to read with a scan tool.

The 2.3 is an Opel design and the 1.7 is Isuzu's, which is worth knowing because the parts trails diverge completely — the 17D appears in Isuzu's own vehicles under its own code, and isuzu-4ee in this catalogue is its later relative.

What goes wrong is old-diesel wear. Glow plugs and their relay are the commonest cold-start fault; injection pump timing drifts as the belt ages and shows as smoke rather than as a running fault; and injector nozzles carbon up and knock at idle.

The 2.3 has a reputation for very high mileage in the Omega and Rekord, at outputs that were modest when new — which is most of why any survive.