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Old 12-21-2018, 08:33 AM   #2
Blue Bowtie
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Re: 2010 Malibu timing chain nightmare. I'm stumped

Welcome Aboard!

From your video post:

"This is a 2010 Malibu ltz 2.4 ecotec with vvt. Changed the timing chains, tensioners, guides, did the procedure to spec by gm/alldata. This whole process is not hard. I followed the steps to a T. Put it all back together, and same damn thing. I knew it was the timing chain to begin with before I did anything. I pulled the valve cover off and voila, loose timing chain between both cam sprockets up top. Before I did anything to this car, I researched the **** out of this car and it's timing chain issues. Every video and description I saw an read was either due to s failed tensioner or broken guide due to lack of oil change etcetera.. ok not a big deal right? Here's the kicker. First off, there is no check engine light and never was. No codes for anything like a p0013-17 etc. Not a damn code whatsoever. (This whole time there has never been a code) so I tear into the front of this motor and I find nothing. No broken guides(not cracked, or worn) sprockets looked OK,(from prior exp with timing chain gears, no excessive wear noticed) and the tensioners operated just like they should. So at this point I'm stumped. I decide to by a whole new kit with all new guides, tensioners and chains.ill also note that when I got to tdc before disassembly, it appeared to be in time still. So I reassemble it all and quadruple check my timing marks. Checked the oil nozzle, tightened everything down. Set the tensioner and put the covers and everything else I took off to do the job in the engine bay. Started it up, and bam, same damn thing. Loose chain. I pulled the cover back off, inspected it and yes the chain was loose. Again, I still have no check engine light. So ive been driving the car with it like this for a few days now. I did notice that the rattle does get s little quieter after about 20 mins, but the pattern of the intermittent chain rattle remains the same even when the rpms are raised, makes the same pattern of rattling only faster and quicker. I checked the cam solenoids for the resistance in each and they are in spec and do work when manually activated. So long story, but my problem is not fixed with the rattle. What the hell could be making it do this? This is not your ordinary failing tensioner or broken guide. I'm so stumped. I'd also like to note that the balance shaft chain was not lose on first inspection. This car has just under 130k miles only. Any help to point me in the right direction. Could this be the cam phaser(s) allowing for this slack in my chain? Anyone else had this synchronous intermittent timing chain rattle??

There is an apparent problem with this vintage engine which GM has never clearly identified. It may be a machining issue, core shift problem, or something similar. It may be years before we really find out, much like the starter pad issue in the '70s.

When the new tensioner was installed, did you measure the overall travel of the tensioner before the chain was installed? I suspect that the tensioner may be at its limit, even though the chain and tensioner are new. This could be due to mounting location/machining problems. A redesigned tensioner (12608580) was released to address problems like this.
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