How to Change the Thermostat in a Holden Commodore Alloytech V6

Alloytech Thermostat locationIn the latter models of the Holden Commodore the Echotech engine was substituted for the Alloytech. For many reasons this engine was mechanically problematic, one such issue was the placement of the thermostat.
The Thermostat is a component that requires replacement semi regularly. What would normally be a simple job in most cars is a nightmare in the Alloytechs. The Thermostat is located on the back of the motor. A position that makes no sense until you discover that the motor was originally designed for front wheel drive east west mounted vehicles.
alloytec thermostat location2There are several methods to getting to this component and all of them are about as much fun as a Jehovahs Witness themed fancy dress party. Most advise removal of the transmission and whilst this sounds like an excessive amount of work it is probably the easiest method to approach this job. Once the transmission is out the job is a piece of cake.
The second choice in the list is the removal of the top half of the inlet manifold. To do it this way you still require small hands and lots of patience.
We have once gotten away with doing this by removing the rear transmission mount, bracing the transmission and pushing the transmission to the side and getting your hands up between the transmission tunnel and the gearbox but the time involved to do this, it would have been quicker to remove the transmission. If you don’t have a hoist available it makes the job much harder.
alloytech how to thermostatSome have gotten away without any of these such methods and just got hands in there to do it. How? Is beyond us but it can be done.
It is strongly recommended that genuine parts be used for this job. The pipes coming out of the housing are sealed with O rings that if not the correct size down to thousands of an inch will more than likely leak. We advise buying the genuine housing, thermostat and O rings.
Whilst doing this job we also strongly recommend you carry  out a cooling system flush and changing the coolant from the factory red to green coolant. Make sure a full flush is done including the heater core. We have found the red coolants are more prone to leaking than the green ones.
If your paying a workshop to do this job, don’t be surprised to be charged anywhere form four to eight hours to do the job.

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