Z06guy07

New to the forum but hoping I could get some advice..... Bought a used Z06 about 8 months ago after selling my 05 Z51. Thank goodness I bought a 07 with a warranty still on it.

Took my 07 Z06 Vette in about 4 months ago for a tick under warranty. Around 1900 to 2100 RPM it had a very distinct tap/tick. Not normal valve sound. You could hear it through the RPM but it was very distinct around that RPM range.

Turned out to be a blown rocker arm. They replaced all the rockers with updated parts #'s (likely due to the dreaded rocker arm flaw). They also had to re-seat a valve that was damaged. I later found out they didn't do the best most proactive measures to eliminate additional damage. They didn't recover all the needle bearings, test the oil filter or oil for shavings/etc... When I asked the mechanic he said many were broken so they couldn't tell how many there was.

After it was supposedly fixed I picked it up and still had the same tick. Really couldn't believe they gave it back to me and didn't notice or maybe they hoped I would just go away. Took it back in and they said this was a different noise and most likely it was "injector noise" and to keep driving it and see if it got worse. Noise got worse so I took it back to the dealer a week later. They had it for a week or two and could not figure out what was causing it. They finally decided to replace the whole bottom end because they thought the sound changed when the clutch pushed in (which it didn't). After taking the whole bottom end apart they didn't find any issues and replaced with all new pistons, rods, etc....

Picked it up after the bottom end was replaced and it still had the same tick. At this point I am dumbfounded that they would return it to me a 3rd time with the same issue like they had fixed it. When I took it back they called in the regional service manager and he called an engineer and they said "oh that is normal noise, LS7's are traditionally noisy." I couldn't believe they would work on my car multiple times for a noticeable tick then try to say it was normal. After arguing with them a few more times after it continued to get worse they finally took it back in again. The mechanic then said "wow that is a lot worse" and found a large amount of play on several of the valves due to wore valve guides on the drive side. When they compressed the spring they could move several of them far more than what the tolerance was supposed to be. They then decided to replace both heads.

Picked it up again and sound was gone...or so I thought. A month later it started to come back. Almost the exact same noise. Took it back in again and they are now sending a regional engineer in to look at it. At this point I don't feel I should settle for anything but a new engine.

All I can figure that would be causing this is a oil delivery issue. At this point they have broke into it multiple times and there has been so much metal in the oil I do not see how it could not have caused premature wear through out the engine.

Any ideas on what could cause this and any suggestions on how to get them to replace the whole engine? I bought it used so Lemon Law is out but the federal Magnuson Moss Act may apply some.

Total time in the shop over 2 months
1st time blown rocker arm
2nd time still had tick (replaced entire bottom end but found no issue)
3rd time found valve guides were wore and put new heads on
4th time......to be determined waiting on the regional engineer.

Car Info:
07 under warranty
Stock except for air intake and mild to wild switch

08VRZ06

IMHO They should have replaced the dry sump oil tank and replaced the oil lines and oil cooler to make sure that there was no left over metal in the oil system.

Mark

Z06guy07

I agree, when I asked him if anything could have made it through the mechanic said the needle bearings were too big to go through the screen to the oil pump. But then when I asked more questions later he said they were all broken up and couldn't count them so if they were broken metal particles would probably have been created.

TurdsOfMayhem

I've kind of accepted my loud ticking as normal since all of my LS motors have done it. However, since you had a or several broken rocker arms, did you notice any power decrease or fuel economy change?

I REALLY want to pull my covers to inspect mine and take pics to post for forum members to scrutinize. But I've never removed them before. Done water pumps, alternators, window motors - that kind of stuff. So slightly concerned about doing it.

Z06guy07

Not any major power loss, although when I got it back after they fixed the broke rocker arm it seemed a little more torqued then normal.

If it had always had that sound I would agree, but it went from nothing to noticeable even by my wife (which normally says I am paranoid) in a few weeks. I have owned many F-Body LS cars and a 05-Z51, all are noisy and have a minor tick to them but those happen through the RPM range pretty consistent. This had a major change (almost like a metal on metal distinct tap/slap) much much louder at certain RPM ranges. You could put it at 1800 and it was barely noticeable, then go to 1900 and it was 4 times louder.

John_P

Z06guy07:

Welcome to the website!

Sorry to hear about all the problems you have had with your Z06!
It is good that you at least have some warranty on the car. I am a fairly new member here also, so I am afraid I can't offer you any experienced advice. But, this is a great forum and I know the veteran members will be able to help you Sir.

Good luck.

---------
John_P

tim414

Wow. Sounds like you you pretty much have a new engine already by them doing bottom end then top.

I would be interested to hear what the engineer finding gonna be...??

tim414

sublime1996525

Sorry to hear that man. I hope you get your new engine. When they run they are great cars and once they get it fixed here's to many trouble free years!

Yawlak80-86

Welcome to the site/Sorry to hear about your problems.


The oil tank and lines can be easily flushed to remove shavings/residue. Was it done by the dealer, highly unlikely.

I wonder if they changed your oil pump and lifters. An unusual ticking noise starting at a certain rpm sounds like its an oil pressure/starvation issue.

Anytime GM reps tell you something is normal and you suspect it's not, just ask them to right it down, (in exactly the same way they told you), on the invoice, then sign and print their name w/ title below it. If they comply. ask the service manager or general manager to do the same. You need to document everything in the event this goes to court.

On a job such as yours, (warranty), the tech gets paid significantly less than if it were a non warranty job. He's going to try and rush it to minimize the loss. I realized the hard way that dealer's and customer service are a waste of time. They will rarely tell you the truth.

IMO Customer Service should be called Corporate Defense. All they seem to do is compile information to see if you have a winnable case in court, (on the bigger issues). They simply weigh out paying for a proper fix of your problem vs. the damage you can do to them if they blow you off.


Good luck, I'm sorry if the post is a little scattered. I'm a bit short on time.

Z06guy07

If the mechanic was good and they followed proper piston balancing and all procedures they follow in the factory I would agree. Just know they haven't replaced everything and with the possibility of damage due to debris and particles would prefer a crate motor. After the mechanic that worked on it told me it was a injector and didn't know count the bearings, check the filter, lines, etc...and after they gave it back to me 3 times with the same issue don't have a lot of confidence in the mechanical prowess of this dealer.

Z06guy07

They did change the lifters the first time when the rocker arm blew. Then the 3rd round they put brand new full heads on.

They found the last time that the source of the noise was wore valve guides on an engine that had 30k miles. Now they put new heads on and it looks like its most likely the same issue again. I know they have a heat sync, heard it was due to the material they used on the guides but wouldn't think it would go out that quick unless there were other issues.

OnPoint

Sorry to hear you're going thru this.

Please keep us posted on what GM says next step is.

Would be great if you could get a new engine out of this (and new cooler, sump and lines).

MTIRC6Z

"The mechanic then said "wow that is a lot worse" and found a large amount of play on several of the valves due to wore valve guides on the drive side. When they compressed the spring they could move several of them far more than what the tolerance was supposed to be."



Hmmm, so they told you a worn guide could be diagnosed without actually removing the valve from the head and using a micrometer to take measurements of both the valve OD and the guide ID. Further, they think the ticking noise could be a result of the guides being excessively worn. Neither of these seem remotely possible to me.

Cheers, Paul.

Z06guy07

When they compressed the sprint they took a measurement of the movement according to what the GM engineer told them it should have. It was pretty noticeable, they showed me one of them and then another that wasn't bad and you could tell the valve had a lot of slack/play in it side to side.

If the valve guide was worn allowing the valve to move side to side when it seated against the head if it was not perfectly aligned would think it could make noise.

That being said since they diagnosed that as the whole problem and replaced both heads it could have been something else that caused it and they never diagnosed it correctly in the first place.

Chevy Cust Svc

Z06guy07,

I'm sorry you have been having this issue with your car. Please keep us updated on how the dealer fixes things.

Thank you,

Evan, Chevrolet Customer Service

hoefi

Don't know about the noise making part. But dectecting "excessive" worn guides is not difficult just by moving the tip of the valve. I found my worn guide by first noticing excessive movement of the tip by feeling them. They were loose enough that I know it's abnormal. By placing a dial gauge at the tip of the valve stem confirmed my suspicion was correct. It was way too loose. Subsequent measurements of the stem with a micrometer confirmed the stem was in spec. Then a mesurement with a bore gauge confirmed the guide was "way out" at 4X the allowable limit.

If it's only a couple of thou over the limit, you can't detect it by feel. Once it's 2X over or more, it's easy to feel it, at least to an experience person.

67redrat

Removing the heads isn't required to check for wear, but it is a hassle. the springs can even be removed, once the piston is at top the center and the valves are wedge to keep from falling. My warranty runs out this December and would like to check for my self if this is an issue with me but my engine runs fine. This is an issue to be aware tho, it could happen at anytime and to anyone. If I go about doing my own check and find worn guides how do I approach GM what is going to be my excuse for the find. Majority of problems is when its too late. Hate for that to happen and the replacement is denied.

hoefi

No excuse is needed. Bring it to a dealer and tell them what you found out and have them fix it. No different than you found out there is a leak under the tranny or the rear axle nut is loose.

GMuffley

The more I read on the subject of worn valve guides, I wonder if there is a recall or class action lawsuit in GM's future.