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Old 12-01-2011, 12:22 PM   #1
ktrsb
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Timing Chain Replacement - 2006 LY7 V-6 3.6L

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.

Last edited by ktrsb; 12-02-2011 at 12:31 AM.
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Old 12-01-2011, 02:10 PM   #2
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

Quote:
Originally Posted by gmtech1 View Post
FYI, a recall has been issued to reprogram pcm with new oil life calibrations.
Thanks, but to be clear, as I understand it (and I am pretty sure I am right), it is not a recall, which has a very specific legal definition, but a Customer Satisfaction Program (No. 10287), and does not apply to the 2004-2006 model year SRXs. Customers to whose vehicles it does apply have until February 28, 2013 to have their vehicles reprogrammed for free.
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Old 12-01-2011, 02:14 PM   #3
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

OK, back on track:

Jack it up:



Remove the lower deflector:



Drain the coolant (writing says have a splash shield ready, this is not a petcock):


Last edited by ktrsb; 12-01-2011 at 03:49 PM.
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Old 12-01-2011, 02:17 PM   #4
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

Remove the strut bar:





Remove the engine cover (just pulls up after removing oil and ps reservoir caps):





Remove the air cleaner and duct:




Last edited by ktrsb; 12-01-2011 at 03:50 PM.
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Old 12-01-2011, 02:26 PM   #5
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

Remove the fan shroud and cooling fan with bracket (mine has heavy duty cooling option):




Four 10mm head bolts, the trickiest one is just above the ABS unit on lower right side of vehicle. Use a 1/4 drive extension and a impact (ball and socket) style u-joint:



Fan bracket comes out with shroud, together. Do not disconnect fan from clutch:







The fan drive has an interesting coupling to the harmonic balancer - bushings and studs, no tool required to separate:

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Old 12-01-2011, 02:50 PM   #6
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

Disconnect brake booster hose to intake manifold:



Remove PCV fresh air hose from intake duct and left cam cover:





Remove dirty air hose from left cam cover and intake manifold inserts (left and right):



Remove and displace evap purge solenoid valve:



Disconnect electrical connectors:



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Old 12-01-2011, 03:10 PM   #7
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

Now time to remove the intake manifold (IM).

Remove insulator for intake manifold tuning valve:



It's a no-see-um 13mm head nut, attached to a ground stud (so be careful the stud remains tight). You can do as I and others have done and loosen the nut, but do not remove, and then tear the insulator:





Disconnect the drive-by-wire throttle body at front and move the retainer down:








I didn't get a closeup shot of it, but the main IM harness connector is a purple one, sitting on top of the right cam cover.

Remove the IM brace (leave the engine cover retaining ball stud alone):





And now the IM retaining bolts. The IM consists of an upper and lower section. To do the timing chain you remove both as an assembly. To do spark plugs, just remove the upper.



I'll sometimes start with the hardest bolt first. In this case, its the rear one. It is below the black MAP sensor, almost straight down from the bend in the manifold:







Use an extension to get to it:



The front one is less hidden:



Then remove the remaining four bolts and disconnect the main IM harness.

Last edited by ktrsb; 12-02-2011 at 08:34 AM.
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Old 12-01-2011, 03:17 PM   #8
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

Set the IM assembly, with the fuel line attached, on the right cam cover/ strut tower (for access to the fuel line connector), and remove the locking clip:





Get a non-glass container (do as I say not as I do), a fire extinguisher, a non-glass-bulb drop light, a no-smoking environment, eye protection, some common sense, and a 3/8" GM fuel line disconnector (the wrench is an easy sizing method). Depressurize by depressing the schraeder valve, covered with a cloth:







A fair amount of gasoline comes out. Dispose of responsibly. You do not have to remove the injectors from the injector rail or the IM.

Remove the IM assembly and set in a safe place:






Last edited by ktrsb; 12-01-2011 at 10:07 PM.
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Old 12-01-2011, 03:29 PM   #9
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

Remove the water outlet with upper radiator hose:







Remove the alt / wp belt:



Remove water pump pulley:



If you didn't drop any of the last 6 bolts into an intake port, now would be a good time to cut a piece of cardboard and tape it in place so you don't:


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Old 12-01-2011, 03:43 PM   #10
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

For the sake of clarity I am posting somewhat out of order i actually disassembled it, as long as it doesn't make a difference. So you might have noticed the ps reservoir and pulley had already been removed by the time of that last picture. If you did, Waldo points for you.

Remove the ps / ac belt:



Remove the ps reservoir, but do not connect the ps lines to it:





Remove the ps pulley:








Remove the ps / ac belt tensioner (you don't remove the alt / wp belt tensioner):

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Old 12-01-2011, 04:07 PM   #11
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

While we are working on the ps, to free the front (timing chain) cover from the ps bracket, you need only remove one bolt, and loosen the second one:





It took some doing to locate that rear/ bottom bolt, and finally did so with a short double-headed 1/4"x3/8" drive ratchet and my ubiquitous impact (ball and socket) u-joint (I have one in 1/4", 3/8" and 1/2" sizes). For clearance, I used the 1/4" ujoint, a 1/4" to 3/8" adaptor, and a 3/8" 15mm (I think) socket.

It helped to disconnect the oil pressure sensor:

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Old 12-01-2011, 04:09 PM   #12
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

OK, more to come. That's probably it for a while.
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Old 12-01-2011, 06:24 PM   #13
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Thumbs up Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

Amazing post, credit to you tackling this number one, number two, it must have taken as much time to take and post the pics as doing the work, better man than I. !!! You disconnected the battery of course?
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Old 12-01-2011, 09:16 PM   #14
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

Quote:
Originally Posted by maxwedge View Post
Amazing post, credit to you tackling this number one, number two, it must have taken as much time to take and post the pics as doing the work, better man than I.
Yeah, I have a lot of pics collected in researching the job so that the downtime would be as small as possible. But posting and writing, yeah, that's a part-time job in itself. Good thing I love writing and teaching.

Quote:
Originally Posted by maxwedge View Post
You disconnected the battery of course?
lolz. Went back through the pics - apparently I pulled the manifold without disconnecting the battery. But yeah, once you do the alternator, you want to disconnect the battery.
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Old 12-01-2011, 09:38 PM   #15
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Re: Timing Chain Replacement - 2006 LY7 V-6 3.6L

Now do the other side - remove the alt bracket. There is no need to and you should not disconnect the alternator electrical connections, nor remove the alternator from the bracket. Nor do you remove the tensioner from the bracket.

Just remove the clip on the bracket that holds the water pipe close, and remove the bracket bolts. Get at the rear one from below the alternator. AND DON'T FORGET TO DISCONNECT THE BATTERY FIRST:







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