Toyota 1KD / 2KD

The common-rail diesel that powered the Hilux, Fortuner and Land Cruiser Prado through two decades — 2.5 litres as the 2KD and 3.0 as the 1KD, and among the most widely used engines in the world outside Europe and North America.

Its known failure is piston cracking on a defined range of 1KD production, associated with injector and EGR behaviour, and it was the subject of recall and extended-warranty programmes in several markets. It presents as heavy blow-by, white smoke and loss of compression — and it is the reason "1KD" and "piston" return so much material. Establish the build range and campaign history before attributing those symptoms to ordinary wear.

The broader theme is that these engines work extremely hard in markets with variable fuel quality, and injector and high-pressure-pump failures traced to contaminated or high-sulphur fuel are common. As with the Renault K9K, one failed injector left in service contaminates the rest of the system, so the question when one fails is how long it has been failing.