Land Rover AJ133 ENGINE REBUILD & REPLACEMENT

APPLICATIONS WE SEE:

The AJ133 appears in the Defender (P525) and the Velar SVAutobiography - the flagship petrol options across the Land Rover range.

WHAT WE REPLACE:

Timing chains, guides, tensioners, bearings, gaskets, and supercharger coupler (where applicable) as standard on every rebuild.

KNOWN ISSUES:

Early AJ133 engines (2009-2012) suffered timing chain guide failure because the guide rails were not strong enough - the aluminium guide rails were weaker than the steel tensioners, causing the tensioner to dig into the guide and wear it down over time, eventually leading to the chain skipping. JLR addressed this in 2015 with a revised guide rail featuring a steel indent, though examples of timing chain failure from 2015 onward have been reported due to carbon and sludge build-up restricting oil flow to the tensioner. Cam phaser failure is also common on higher-mileage examples. Rattling on cold start is typically caused by worn chain tensioners failing to maintain adequate tension before oil pressure builds. Land Rover AJ133 Generations/Revisions The AJ133 underwent several revisions during its production life: Early engines (2009-2012): Timing chain guide rails were made of aluminium and were weaker than the steel tensioners. Tensioners would dig into the guide rails and wear them down over time, potentially causing the chain to skip. 2013-2014: Incremental improvements to the timing chain system. 2015 onwards: JLR introduced a revised guide rail featuring a steel indent to address the wear issue. However, examples of timing chain failure from 2015 onward have been reported due to carbon and sludge build-up restricting oil flow to the tensioner. Naturally Aspirated vs Supercharged: Supercharged variants carry additional components including the supercharger, supercharger coupler, and associated cooling system.