No Oil Pressure in Holden V6 Alloytec - Timing Chain Tensioner Gaskets

Replacement Timing Chain Tensioner Gaskets on Holden Alloytec V6

The Issue

A customer fitted a set of replacement heads to a VZ V6 Alloytec engine. A new timing chain kit was also fitted at the same time. When started, the engine had no rattles but the low oil pressure warning light came up on the dash. 

The Diagnosis

An external oil pressure gauge was fitted and the engine started. The engine showed zero oil pressure at idle where it should have been atleast 10 psi. It showed 40 psi at 2000 RPM. 

The oil pickup was inspected using a camera and showed to be clean (in older motors oil sludge can block the pickup). The next step was to remove the timing cover and inspect the components. 

The Findings

The V6 Alloytec has three timing chains along with three timing chain tensioners. These three tensionser are hydraulically actuated using pressurised oil from the engines oil system. This means the chain slack is kept to a minimum and also allows for automatic adjustment. Each of the tensioners has an oil jet that sprays oil onto the chain to lubricate it whilst the engine is running. 

Each of the tensioners has their own small oil reservoir that sits between the body of the tensioner and the mating surface. This ensures a smooth and quiet startup, for when there is no oil system pressure yet. This reservoir of oil is contained within a rubber covered metal gasket, which seals the tesnioner to the block or the head. 

When the timing gear is removed and replaced, these gaskets can fall out or be damaged.

In this example, one of the metal gaskets had not been replaced upon reassembly. This is where the oil was escaping, thus causing low oil pressure. 

The Solution

A new set of gaskets for the tensioners were fitted and the engine reassembled. The engine then had full oil pressure both at idle and throughout the rev range. 

As shown in this scenario, a very small part can cause a very big problem. It was just one small component that caused the engine to have no oil pressure. The real lesson here is to ensure you replace all gaskets on reassembly, leave nothing out even if it appears unnecessary. 

Important Note

The timing chain assembly on the Alloytec V6 is a complicated system, one that requires a lot of care in assembly. When undertaking this repair and replacement, be sure to check that every part is back the way it should be, and follow the service manual to the letter.