MTPZ06

I'm thinking lifter issues. Valve issue is more of a silent killer...no issues until boom.

tomcat11

I too hoped that by buying a 2012 might stand a better chance of not having any problems. My decision was based on all the information I could gather from this site, the action center (Hib Halverson), and GM's own published statements. I bought my car back in February with 11K miles and immediately changed the oil and filter. I decoded the engine build date to 10/20/11. I put about 2100 more miles this last summer and enjoyed the hell out of the car. Very quiet valve train and seemingly no oil consumption but....always in the back of my mind was the uncertainty and I was always listening to the engine. Finally a couple of weeks ago following my instinct I did the correct best method wiggle test as described by Hib.

The very first valve (intake) I checked had .0045" movement. I stopped and started the process of removing the heads. Once removed I discovered 6 of 8 intakes were out of service limits but surprisingly the exhaust valves were good. Wait no it gets worse. Several of the intakes had worn through the chrome nitride coating. There was also a paisting of oil in the intake ports and a ton of carbon deposits on the piston crowns. What a mess.

My heads are down at AHP getting the full treatment as we speak and I am cleaning and inspecting the rest of the valve train. I recently read Katech's article about what they have seen over the years and I am now 100% convinced that the problems with this engine are numerous and pervasive. From the aluminum lifter bores, ti coatings, and all the other known problems it seems this engine was bean counted and pushed out without being engineered for reliability over the long haul. The design is very good but the materials are questionable and I can see the short cuts they took. Ya Ya I know all about price points bla bla, It's a flag ship car for gods sake!

What a disappointment to say the least and such a shame for such a legend of a brand/make. Glad I checked and tore it down when I did.

Hirohawa

I had a lot of noise turned out to be bad lifters only. Guides were all in spec.

Aggiecatcher

Just having a crate motor installed this week. My crate motor comes with a 24 month 50K warranty. Why not wait until my two years are up before spending the money on this issue? Thoughts? I'm already looking at new Z06's, so I'm not sure I'll even have it that long.

Landru

Mess w/ a crate engine's heads (or any other component) will void warranty.
Owned an '08 its entire life, always covered w/ GMPP/GMEPP & as such left LS7 stock per warranty requirement.
Since GM limits renewals to 3 I was SOL forcing me to take a proactive decision re having heads rebuilt.
Leave it alone, enjoy w/o fear the warranty period, knowing if it frags GM's on the hook for a new one.

All the more reason to leave it be.

G8Pumpkin

Iam basicly in the same boat as you glad I pulled mine apart before it let go, check your camshaft carefully for any signs of wear mine was just starting to fail. I too think its a shame the General did not use better quality parts the basic design is good just fails in the execution department.

tomcat11

Do you have any pictures of your camshaft? Proper inspection is difficult to do without removing it which I would like to avoid at this point. Some of my lifters have very small fine lines on the rollers which may be the result of some trash, possibly scuffed aluminum from the lifter bores. The lifters also have some scuff marks on the their bodies. From what I can see with both eyes and boroscope I think the polished looking surface with some frosted lines on the cam lobes may be normal wear as the surface of the lobes seems smooth with no grooves or surface pitting or spalling. I have a new set of Delphi lifters going in.

Les

Here's a lobe gone bad- second lobe from the right. Pretty easy to spot.

Les

Same lobe, different angle.

Les

One that would probably degrade fairly soon- second lobe from the left. Running my fingernail across it, I can just barely feel it catch on those two lines.

tomcat11

Yes that is pretty obvious. I think mine all look similar to the other adjacent lobes. I don't like these frosted lines but I am an old school racer and have decades of flat tappet experience but am fairly new to these hydraulic roller set ups. Is this the soft cam/material/heat treat issue or was there another problem?

Les

No other problem I'm aware of, so yes. Honestly, if I was in your situation I'd just be safe and put a new cam in while I'm in it that deep. It's relatively small change to eliminate the risk of failure, considering the damage it could cause.

Undy

Here another one...

G8Pumpkin

Here is a pic of mine that is just before what happens as shown by other posters pictures where there cam is definitely toast mine is headed that way so I replaced it. You can do it without pulling the motor there is a video on ytube that shows and explains some of the steps. I watched that and did mine and learned the following as I went, the steering rack does not have to be taken all the way out of the car just slide it over to the passenger side so you can get at the crank damper.
Take all the accessories off the front of the motor the air conditioning condenser will swing up and then pivot back and sit on top of the motor with the lines still attached so no need to discharge the a/c.
Take the power steering reservoir off, undue and remove the ABS bracket from the frame and the ABS unit total 4 bolts and pry it up as it sits in a rubber mounted stud,
remove the 2 lines from the steering rack that go to the cooler at the rack and take a picture before you do this so you can figure out where the lines have to go relative to the reservoir lines will save a lot of time putting it back together,
take the fans out the bottom of the car much easier that out the topside think also the same for the radiator I removed mine out the top but when reinstalling figured out it would be simpler out the bottom
I did all mine on jack stand in my garage would be nice to have a hoist but not necessary
clean the a/c condenser of dirt it will be packed took me a long time with an air hose and a vacuum as I have a very small compressor so was constantly waiting to build air pressure, the rad on mine had very little dirt its the a/c condenser because of the much smaller fin opening traps the dirt but it also shuts off the air supply to the rad which is behind it.
I used Johnson 2110 slow leak down lifters which are more expensive than the OEM but in my research the stock GM lifter only gives accurate cam translation to the rocker arm 65% of the time vs the Johnson which is supposedly 95% so you gain performance right there by not losing lift and duration at the valve, apparently this is why GM use the slow leak down lifter in the COPO Camaro car from the factory, these will require a new pushrod length but you should put in better pushrods anyway the factory ones are poor and pushrods are not expensive.
You will need 2 tools I longer bolt for installing the timing cover and the crankshaft damper you can get the centering tool and the bolt on ebay at a decent price for the real Kent Moore tools
For a camshaft I went with Cam Motion and there $50.00 upgrade to the best core still waiting for the machine shop to finish my heads should have them in a few days then I can finish reassembly.
If you are doing going this far with things put in a better crankshaft damper than the stock GM one which has a habit of failing down the road I used a middle of the road Power Bond one its cheaper than OEM any way and I only wanted to do this job once as it is a fair bit of work.
I will post a separate thread on the oil pump to explain a bunch of things

tomcat11

Interesting that although I see pitting next to the damaged area on that lobe I do not see the frosted lines on that lobe.

Gearpuller

I was also aware of the valve guide Issue when I bought my 2010 Z in Oct 2014. it had 21,500 miles on it at the time.
Drove it 500 miles and it bugged the hell out me every time I started it wondering if it was the last time.
Checked them at 22,000 miles and found 7 intake and 3 exhaust wiggled.

But has other posters have said you may some other problem.

Even still you should check them or have them checked. Better yet just have them fixed.
I have seen a 08 Z with 15,000 easy mile early this year have most of the valves wiggle.
He replace his with AHP heads and stayed stock.

Then I read your post about taking it to AHP after I type my post. Good choice.

73DBG

Spaceme1117

Could part of the problem of excess valve guide wear be from the 1.8 ratio rocker arms putting too much side loading onto the guides? Would rocker arms with a roller tip help with the problem?