Chevrolet High Value V6 (LX9 / LZ9)
V6 · naturally aspirated · petrol · 2004–2011
Also known as: lx9, lz4, lz9, lz8, lze, lgd, high value v6, 3.5 v6 pushrod, 3.9 v6, la3, l66, lz0
General Motors' last pushrod 60° V6 — 3.5 and 3.9 litres, in the Impala, Malibu, Monte Carlo, G6, Uplander, Rendezvous, Aura, Relay and Vue. It is the direct descendant of the 3100 and 3400, and its faults are largely theirs.
Do not confuse it with the High FEATURE V6, which is a different engine entirely: overhead camshafts, 3.0 and 3.6 litres, sold at the same time in some of the same cars. The names differ by one word and the engines share nothing. Establish which is fitted before quoting anything, because a 3.5 pushrod and a 3.6 DOHC in the same model year are not variants of each other.
The family fault is the intake manifold gasket, inherited from the 60° V6 line: a composite gasket that the metal either side works loose as the engine heats and cools until coolant escapes — or, worse, gets into the oil. Coolant in the oil on one of these is the gasket until proven otherwise, and the revised gasket with thread-locked bolts is the repair rather than a head job.
The 3.9 is unusual and worth knowing about: it is a pushrod V6 with variable valve timing, achieved with a single phaser on the camshaft. It is the only variable-timing engine in this family, it sets correlation codes when the phaser or its oil supply fails, and a procedure written for the 3.5 does not cover it.
Cars fitted with this engine
11 generations, across 5 makes. From the authored catalogue — an absent car means the catalogue has not reached it, not that the engine was never fitted.
Cadillac
Chevrolet
Pontiac
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Posted about this engine
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about High Value V6 (LX9 / LZ9).