Sounds too logical but Always Always Always check for a loose plug before going inside......did you?
Has anyone actually indicated that a replacement of the valve adjuster thing actually fixed it?I think mnviper, iggy, and one other have reported this issue recently.
mnviper, post a picture of your odometer and I'll award you a 100,000 mile badge.
It is, if they're not pumped up (recently done an oil change, or car has been sitting for a long while). They should retain oil pressure when the car is shut off, though. That's why it doesn't clatter like crazy on startup like some cars may do for a few seconds after an oil change.I see some in this thread seem to indicate that it might be normal to be able to push down on these hydraulic cushion things when they have no oil pressure. However as I understand it on my engine, only one of these can be pushed down, and even then it's not able to be pushed 100% of the time.
Interesting... wonder why some might not keep oil inside, but most do... and if that in itself is a sign that something is wrong with them.It is, if they're not pumped up (recently done an oil change, or car has been sitting for a long while). They should retain oil pressure when the car is shut off, though. That's why it doesn't clatter like crazy on startup like some cars may do for a few seconds after an oil change.
Can you please share with me your invoice, so GM knows exactly what to replace. I am having the same intermittent as you were having. You are the only one that i can find that has the same intermittent noise my is making. I would greatly appreciate it.Ok, so here's the run down... I got my car back , including the 16 valve adjusters / lifters ( or whatever you want to call them ) that were replaced.
One out of 16 can easily be compressed with your fingers, the other 15 are virtually impossible to compress more then a tiny amount ( a few thousands of a inch at most ). My car runs like a champ now, probably better then it has in months, maybe longer. I've only driven it about 100 miles since I got it back , but during that time I averaged almost 37MPG. Now, there have been times in the past when I can average that much on a longish highway type of trip, but over the past 6 months to a year, I can't really remember a time when I had done it in this car.
Using a stethoscope before the repair when this ticking was present, I was able to hear quite well that the ticking was coming from beneath the valve cover, on the intake side. Now, being my problem was intermittent , there were also times when the ticking had gone away, with no ticking sounds at all coming from under the valve cover. After the repair, with the stethoscope on the valve cover, all you hear are nice whirring noises, nothing odd sounding at all.
For kicks I put the stethoscope on the fuel rail, you can for sure here a ticking coming off the fuel rail. Without the stethoscope , the injector ticking is barely audible to my ears ( with fairly bad hearing ).
For anyone who may be reading this and trying to diagnose your own ticking noises... if it sounds like a lifter, it probably is a lifter. At least that's my opinion... Anyone who's ever heard a bad lifter, knows the sound, it's significantly louder then any fuel injector I have ever heard. When my lifter was ticking, you could hear it easily ( even with my bad ears ) by rolling down the window and listening. If you put your ear up to the top of the valve cover, the noise was clearly coming from under the valve cover.
I personally wonder how many of these parts fail... how many fail intermittently , and even how long mine might have been causing less severe problems with out me even knowing it. As I had said before, even after this issue became more obvious, I did not have a check engine light come on, except for two times, when I was purposely out driving it hard to try and figure out what was going on. Having a Bluetooth OBD2 device and the Android App 'Torque', was really helpful to me on this issue. When the noise was at it's worse, you could see the knock retard parameter jump to 15 degrees or higher. After my repair, on my normal driving with regular gasoline, the knock retard hasn't gone above 3 degrees. I suspect that my lifter had been partially failing , and gone undetected for quite some time and that it wasn't until it got to the point where it was failing much more frequently that I actually noticed that it. I'm only speculating, because I don't make a habit of running my Torque app on a full time basis, I basically only use it if I'm trying to diagnose a problem.
Cost me $120 for 16 new lifter / adjusters, because I asked to have them all replaced, while technically there was only one bad one detected. Also had to pay for a valve cover gasket, which I think was around $25. But the major cost was 4 hours of labor. All total this repair cost me just over $500.
Could you do this repair yourself? Not very likely, unless your a good mechanic, but even then there's a special set of tools that GM dealers can get that make the job less prone to errors. By errors, I mean getting the timing of the cam shafts all out of wack and damaging the motor / valves in the attempt to repair. The kit consists of a round shaft that holds the crank still during the repair ( goes in through a cover on the side of the engine ), another little thing that looks like a allen wrench, that apparently holds some other thing in place during the repair... this big aluminum bracket and a few other do-dads. I don't know the cost of the kit, but I bet it cost my dealer as much for this kit then they made on this repair. I told my mechanic friend... " well, your experienced now, if anyone else comes through the door with the problem, you'll know exactly what to do". I also asked who paid for the tool kit, and was told that the dealer bought it. Needless to say, I am glad to have a good local shop that I can trust , cause I suspect that if you were clueless about this repair, you could get burned pretty easily by a shady shop. But you should be aware that this is not something a novice mechanic would likely be able to do on their own, even if you had the tool kit, it's not a trivial thing to do.
As a side note... They found my water pump to be weeping, and I got that repaired under the extended warranty for those...
Moral of the story... if you have a ticking noise that seems louder then it should be, check it out further, don't just assume it's fuel injectors like so many people are told. There is a distinct difference between these valve ticking noises and a fuel injector ticking.
And personally, I really have no reason to believe this failure as oil related. My best guess is that it's just a somewhat non-typical parts failure. The fact that I actually have a brand new lifter / adjuster that did not move freely when I bought it, but now moves in and out very easily after I accidentally dropped it, really makes me very curious about exactly how these parts work. I'm tempted to try and tear one apart to see exactly what's inside and what actually fails on them. As of yet, I haven't been able to find a really detailed drawing of exactly what's inside one. There are a lot of other similar parts out there , ones that I have seen drawings for , but I still don't fully understand how these things actually work.