My 2006 SRX has the 3.6L V-6 engine, RPO Code LY7 (also known as the "High Feature, HFV6 and Alloytec). I have driven it since new, about 161K miles.
About a year and a half ago, it started getting very noisy at idle - a constant noise, somewhere in pitch between a whine and a roar. Like a bad bearing.
Then it started rattling, like the lifters had low oil, for about 5 seconds at startup. The noise was concentrated on the front of the engine, and did not seem to be coming from the camshaft covers. I only had the noise, no check engine lights (CELs).
The weak link (no pun intended) on these engines is the oil life interval and how it affects the primary timing chain. Many owners (CTS and other GM products use a similar engine) claim to have experienced noise and CELs associated with the elongation of the primary timing chain due to excessive wear. Some claim to have chain failures, with resulting valve to piston contact and damage. As noted by the next 2 posts, GM instituted a Customer Satisfaction program to re-program the engine oil life monitor.
I finally got around to disassembling the engine, and confirmed that the timing chain had elongated, had excessively worn the timing chain guides. The noise was likely from a combination of the chain slapping against the chain guides and tensioner shoes, and the worn teet on the primary chain gears.
This thread is intended to document for others how to go about making this repair. I have essentially done a "core dump" of pictures and information at my SRX's website, srxturnsignals.shutterfly.com.
To start with, let's familiarize ourselves with the LY7 engine. Here is what it looks like in the SRX (the CTS has a different oil pan):
In this writeup I will try to use the standard naming convention, where the front of an engine is the pulley side, regardless of its orientation in the vehicle, and the back of the engine is the flywheel side. In a RWD vehicle with typical longitudinal engine placement, this should'nt cause an issue, but this same basic engine is used in FWD vehicles as well. So the right bank is on your left hand, if you are standing at the front of the car, looking to the rear.
Also, cylinders are numbered, from front to back, 1, 3, 5 on the right bank, 2, 4, 6 on the left bank. Firing order is 1, 2, 3, 4, 5, 6.
My engine looks somewhat different, in that I have a factory-optioned towing package that includes heavy-duty cooling. So I have a different setup on the front, and I don't have the idler pulley between the harmonic balancer and the ac compressor.
Here is another view - it will help you understand some of the hoses, lines and nuts that need to be removed from the backside:
Here is a front view:
OK, next post we will start disassembly, with the ultimate goal of removing the front engine cover (the timing cover) to expose the timing chain.