I'm not saying it's not, but in the process of hunting it down, it would be a good exercise to start from scratch. Noises can be a hard thing to chase down, and one thing that could help with locating the source of the actual noise is to temporarily dismiss the idea that it's chain slap. When the engine slows is when the valve timing would change, then when sped up it would go back into proper time, but with a loose chain it's possible that it would run rather poorly when accelerating, intermittently running well and then less well in concert with the noise. It's kinda hard to believe that the engine would run acceptably with a chain that loose and then also not pop a code. But with what you've posted above, that's not likely the case, either. With a loose chain, my concern would be that the chain is too long (one link too many?) and the tensioners just can't take up that much slack, or one of the tensioner pins was never pulled and keeps a tensioner from being engaged with the chain fully. So here are some ideas that may or may not pan out. You already covered what I was gonna suggest - the cam phaser solenoids. Every time I pull the valve cover off there is slack between the cams. I know it's hitting the upper chain guide. Also, when you rev it up, the chain rattles faster and still has that brief pause in it before it rattles more. Does the same thing when first started, to well after driving it for a while. Could this be the cam phaser(s) allowing for this slack in my chain? Anyone else had this synchronous intermittent timing chain rattle? Any help to point me in the right direction. I'd also like to note that the balance shaft chain was not lose on first inspection. What the hell could be making it do this? This is not your ordinary failing tensioner or broken guide. So long story, but my problem is not fixed with the rattle. I checked the cam solenoids for the resistance in each and they are in spec and do work when manually activated. I did notice that the rattle does get a 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. So ive been driving the car with it like this for a few days now. Again, I still have no check engine light. I pulled the cover back off, inspected it and yes the chain was loose. Set the tensioner and put the covers and everything else I took off to do the job in the engine bay. Checked the oil nozzle, tightened everything down. So I reassemble it all and quadruple check my timing marks. 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. 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. (This whole time there has never been a code) so I tear into the front of this motor and I find nothing. No codes for anything like a p0013-17 etc. First off, there is no check engine light and never was. Every video and description I saw an read was either due to a failed tensioner or broken guide due to lack of oil change etcetera. Before I did anything to this car, I researched the **** out of this car and it's timing chain issues. I pulled the valve cover off and voila, loose timing chain between both cam sprockets up top. I knew it was the timing chain to begin with before I did anything. Put it all back together, and same damn thing. Changed the timing chains, tensioners, guides, did the procedure to spec by gm/alldata.
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