Question: 2007 LS7 lifter noise

[C5NGAGE]

I have been gone for quite a while and may have missed this topic, but it has cropped up on my 2007 Z06 with 26,000 miles and I need some input.
2,000 RPM up thru 2,600 RPM lifter tapping on the right (passenger) side is very very noticeable.
I had needle bearing in the oil and replaced al the rocker arm bearing with Harland Sharp units thinking that was the tapping cause.
After the GMPP covered the cost to replace three of the broken rockers bearings (while I paid for a full set) I was disappointed to find the lifter noise was still there.
I let it go after several folks told me that is just a noisy engine. The Dealer that has generally been very good said yeah that is lifter noise but until the engine is showing Error Codes in the DTC GMPP will not cover the repair. The repair from them was a new set of lifters and cam. At my cost over $3,000 at a dealer.
Then I started reading about broken exhaust valves and worn valve guides. This did sound like that issue initially. I also read about Roller lifters rotating at mid RPM and tapping????
I read about cracked Lifter retainer caps due to over revving. I read about the high flow oil pump from KaTech. Linked Roller Lifters from Lunati, different oils even oil additives can fix the problem.
I don't mind paying for a fix if the GMPP won't, I just want to keep my engine all in one piece and prevent the daylight seeking piston syndrome. Been there, done that elsewhere.
is there any concrete research to define the issue, clarify a good fix and validate it does not come back. Short of Cam, Lifters, Oil Pump, Heads, all thrown at the problem at once as suggested by one Corvette Specialist???? I hoped to find serious research done and posted but am unable to find anything that presents a clear understanding of the problem. Oil flow, lifter design, etc etc.
Hoping some of you smart folks here will know what I am talking about and know of a good fix.
Thank You CAC

 

[Hib Halverson]

I have been gone for quite a while and may have missed this topic, but it has cropped up on my 2007 Z06 with 26,000 miles and I need some input.
2,000 RPM up thru 2,600 RPM lifter tapping on the right (passenger) side is very very noticeable.
I had needle bearing in the oil and replaced al the rocker arm bearing with Harland Sharp units thinking that was the tapping cause.
After the GMPP covered the cost to replace three of the broken rockers bearings (while I paid for a full set) I was disappointed to find the lifter noise was still there.
I let it go after several folks told me that is just a noisy engine. The Dealer that has generally been very good said yeah that is lifter noise but until the engine is showing Error Codes in the DTC GMPP will not cover the repair. The repair from them was a new set of lifters and cam. At my cost over $3,000 at a dealer.
Then I started reading about broken exhaust valves and worn valve guides. This did sound like that issue initially. I also read about Roller lifters rotating at mid RPM and tapping????
I read about cracked Lifter retainer caps due to over revving. I read about the high flow oil pump from KaTech. Linked Roller Lifters from Lunati, different oils even oil additives can fix the problem.
I don't mind paying for a fix if the GMPP won't, I just want to keep my engine all in one piece and prevent the daylight seeking piston syndrome. Been there, done that elsewhere.
is there any concrete research to define the issue, clarify a good fix and validate it does not come back. Short of Cam, Lifters, Oil Pump, Heads, all thrown at the problem at once as suggested by one Corvette Specialist???? I hoped to find serious research done and posted but am unable to find anything that presents a clear understanding of the problem. Oil flow, lifter design, etc etc.
Hoping some of you smart folks here will know what I am talking about and know of a good fix.
Thank You CAC

You say this is "very, very noticeable". Are you sure this is lifter noise and valve noise? Have you used a listening device of some sort to try and better locate the noise? Lisle makes a really good automotive stethoscope. You can use that to see if the noise is lifters, valves or something else.

If you are sure it's valve noise, know that excessive valve noise is one characteristic of an engine with worn valve guides. You need to have the stem-to-guide clearances measured. Most in the hobby call this a "wiggle test".

The dealer who spoke to you before is not giving you a straight answer.

A Service Bulletin was issued early last year. The executive summary is that you have to have either noisy valves, excessive oil use or an MIL for misfire to get GM to inspect the engine (ie: the "wiggle test" for worn guides) at its expense, however, you can also ask a dealer to test the engine and pay for the testing yourself. If they measure stem-to-guide clearance and find any valves out of spec, GM will repair the engine and reimburse you for the expense.

As for the other issues you raise...

1) No stock LS7 needs a Katech oil pump.
2) Under normal circumstances, LS7 lifters cannot "rotate" in their bores. If they do, your engine would have already failed.
3) No stock LS7 needs Lunati linked lifters
4) There is no pour-in oil additive needed
5) A change in engine oil is very unlikely to affect this problem, but long-term durability might be improved by going from Mobil 1 5W30 to Gibbs Driven 5W30.

 

[C5NGAGE]

LS7 lifter noise

[QUOTE=Hib Halverson;1153391]You say this is "very, very noticeable". Are you sure this is lifter noise and valve noise? Have you used a listening device of some sort to try and better locate the noise? Lisle makes a really good automotive stethoscope. You can use that to see if the noise is lifters, valves or something else.

1) No stock LS7 needs a Katech oil pump.
2) Under normal circumstances, LS7 lifters cannot "rotate" in their bores. If they do, your engine would have already failed.
3) No stock LS7 needs Lunati linked lifters
4) There is no pour-in oil additive needed
5) A change in engine oil is very unlikely to affect this problem, but long-term durability might be improved by going from Mobil 1 5W30 to Gibbs Driven 5W30.[/QUOTE]

I have a stethoscope I will validate what 4 separate mechanics tell me, lifter noise. I know the injectors are clacky but this pretty noticeable. I may still have my decibel meter I will see from one side the other the noise levels. If I can find it. Appreciate the input, I would have thought this issue would have been more of a recorded historical event with know fixes.

this was all good input it did not make sense to me either but I had nothing else to go on,
thank You

 

[Hib Halverson]

You didn't mention in your OP that four different technicians told you there is a faulty valve lifter. If that's the case, get the intake manifold and the valley cover off and replace the lifter(s) which are faulty. Also, inspect the camshaft. If the faulty lifter has damaged a lobe, replace the cam, otherwise leave it alone.

Then, change the oil and filter and road test.

dB meter won't tell you a thing that you already don't know.

LS7s do not have a history of problems with lifters. The engine's two documented problems have been some early engines with bad rocker arms and problems with valve guide wear on most model years. With both these problems, some engines have them but most do not.

For more information on the LS7 see this article here on the CAC.

 

[C5NGAGE]

Stethescope test

I got my stethescope out and had my wife take the RPMs from idle to 2,500 and hold it. We did this twice while I listened to sounds under the valve cover and exhaust manifold. I also listened to the Idler bearing on the drive belt and the Oil Tank of the Dry sump system for comparison.
I could hear tapping at idle.
I checked the injectors and of course they were were tapping but lighter.
I tested on the exhaust manifold and the tapping was very low and the rush of exhaust was whooshing.
The Bearing on the idler was whirling like you expect, not rough or grinding.
The oil tank all you heard was liquid splashing not tapping. That was interesting.
When my wife took the RPMs up to 2,500 the tapping under the valve cover turned in to a hammering!
At 2,500 i also tested the exhaust manifold again and is was exhaust whooshing not hammering or tapping. Thinking this could mean the valve guides are ok but the lifters are toast.
While not clear exactly, I hope it is not the valve guides and maybe just the lifters. The question is if the cam is hurt in any way.
I guess to pull the lifters and test the cam lobes is the next step. and the check the valve guides at that point.
Kind of sad to have put all this money into this Z06 and have a basic engine component failure.
I already did the Rocker arm bearing, now lifters. thanks for the guidance.
I hope GMPP will help somewhere in all this.

Update to status:
GMPP came and heard then after three days thinking asked to have the passenger side head pulled for inspection.
I am in a rental car, the shop has had my car a week and no billable work has been done. They think I have to pay them for this tear down. The Intake can stay because the Lifters are under the head in a closed cavity, they are not under the intake manifold like on the old Mouse and Rat motors. I also read there was a lifter oil filter under the oil pressure sensor, maybe need to look at that. Missing out on some great cruising weather too Dang it. More later

 

[C5NGAGE]

LS7 Lifter Noise Update

Wow! There is news folks and while the engine did not destroy itself it is only a miracle that it did not.
We have the Passenger head off and again found roller bearings in inside.
The head looked clean intact and no visible signs of damage or wear.
Several Roller Lifters appeared to be missing some roller bears but I also had the rocker arm bearings fall out so ...
The GMPP inspector asked the shop to pull a set of springs off so he can measure Valve guide wear.
When he returned the exhaust valve which looks fine actually just fell out and at 1/2 of travel had 1/8 or more wobble.
The stem was scored the guide was egg shaped and it was clear ALL the exhaust valves were on their way to seekign daylight. Wow!
We are now waiting for the Estimate to repair and see how much labor GMPP will cover.
Now I am worried to repplce the Exhaust valves wth the light weight sodium filled valves or go with heavier Stainless steel.
And the Lifters and Cam needs replacing so I am reading the GM Performance catalogues for the old Super Duty type parts but I can't realy figure out for the LS7 what would be best. Would like to see 150,000 miles after this repair?

Well that is the update. If you have an LS7 please get it inspected and you have to pull the Spring off which can be done with the head left on. And verify the exhaust valve guides are OK. You can see where the stem will eventuially just give up and LS7s do not digest Exhaust valve heads very well.

More later, Dennis
:ugh

I got my stethescope out and had my wife take the RPMs from idle to 2,500 and hold it. We did this twice while I listened to sounds under the valve cover and exhaust manifold. I also listened to the Idler bearing on the drive belt and the Oil Tank of the Dry sump system for comparison.
I could hear tapping at idle.
I checked the injectors and of course they were were tapping but lighter.
I tested on the exhaust manifold and the tapping was very low and the rush of exhaust was whooshing.
The Bearing on the idler was whirling like you expect, not rough or grinding.
The oil tank all you heard was liquid splashing not tapping. That was interesting.
When my wife took the RPMs up to 2,500 the tapping under the valve cover turned in to a hammering!
At 2,500 i also tested the exhaust manifold again and is was exhaust whooshing not hammering or tapping. Thinking this could mean the valve guides are ok but the lifters are toast.
While not clear exactly, I hope it is not the valve guides and maybe just the lifters. The question is if the cam is hurt in any way.
I guess to pull the lifters and test the cam lobes is the next step. and the check the valve guides at that point.
Kind of sad to have put all this money into this Z06 and have a basic engine component failure.
I already did the Rocker arm bearing, now lifters. thanks for the guidance.
I hope GMPP will help somewhere in all this.

Update to status:
GMPP came and heard then after three days thinking asked to have the passenger side head pulled for inspection.
I am in a rental car, the shop has had my car a week and no billable work has been done. They think I have to pay them for this tear down. The Intake can stay because the Lifters are under the head in a closed cavity, they are not under the intake manifold like on the old Mouse and Rat motors. I also read there was a lifter oil filter under the oil pressure sensor, maybe need to look at that. Missing out on some great cruising weather too Dang it. More later

 

[Hib Halverson]

Ok...I'm posting to an old thread..

Glad you found the problem.

Relax. You have the rocker arm bearing problem. There was a run of 2007s which had engines built with defective rocker arm needle bearings.

By now you should have had all 16 rockers replaced with your extended warranty.

If the engine is now quiet, you probably have no other noise problem but it's unlikely you have trouble with valve guide wear but it's not impossible.

If you are worried about guide wear and are getting stressed from all the hysterics you read on other forums about exhaust valves, before you do anything more have your engine "wiggle tested". That will determine of you have any issues with valve guides.

 

[C5NGAGE]

oil sampling tells a story

Ok...I'm posting to an old thread..

Glad you found the problem.

Relax. You have the rocker arm bearing problem. There was a run of 2007s which had engines built with defective rocker arm needle bearings.

By now you should have had all 16 rockers replaced with your extended warranty.

If the engine is now quiet, you probably have no other noise problem but it's unlikely you have trouble with valve guide wear but it's not impossible.

If you are worried about guide wear and are getting stressed from all the hysterics you read on other forums about exhaust valves, before you do anything more have your engine "wiggle tested". That will determine of you have any issues with valve guides.

Hi Guys,
the engine has received new heads, lifters, and dropped the oil pan for clean out, new exhaust valves, and all gaskets, bolts etc.
the clincher was oil samples. I had oriGina oil from 2 years ago 0 ppm titanium.
oil from last May 20,000 miles 3 ppm Titanium. Current oil before repairs 9ppm Titanium. The exhaust valves are Titanium. Based on the oil samples and disassembly GMPP stepped up up. $7,000 later repairs were done. They refused to pay for a new cam or the oil pan clean out. The cam did seem ok but when we found bears in the oil pick screen I was disappointed they would not cover that cost.
Bottom line, if you own a Z06 get oil samples tested, cheap predictive detection of self destructive engine condition. Keep records and trust your own judgement. No one I spoke to thought this was a big deal. Yet I have seen videos of exploding LS7s.
I hope this helps some of you to protect your engines and yourselves. The engine is quiet and has more power. I have 28,000 on this Ron Fellows and I plan to keep it until I am dead.

 

[Hib Halverson]

(snip) I plan to keep it until I am dead.

Now that's what I'm talking about!

 

[Iroc2Vette]

You didn't mention in your OP that four different technicians told you there is a faulty valve lifter. If that's the case, get the intake manifold and the valley cover off and replace the lifter(s) which are faulty. Also, inspect the camshaft. If the faulty lifter has damaged a lobe, replace the cam, otherwise leave it alone.

Then, change the oil and filter and road test.

dB meter won't tell you a thing that you already don't know.

LS7s do not have a history of problems with lifters. The engine's two documented problems have been some early engines with bad rocker arms and problems with valve guide wear on most model years. With both these problems, some engines have them but most do not.

For more information on the LS7 see this article here on the CAC.

I recently re-read the article on the LS7. The valve guide issue is making me very nervous. I'm going to have to keep a eye and ear on my oil level and engine noise. I know these engines are rather 'talkative' due to the aggressive cam profile and stiff valve springs. The issue that really scares the wee out of me is the fact the replacement heads were also defective. I have talked to a 'insider' from GM QC who said the heads were probably left up to the supplier to provide inspection after Feb. 2011. GM, he thinks, doesn't do the inspections themselves. To me, this is akin to telling the criminal to police himself. This issue has been really exploding on another site. One person said he talked to a couple of members of the the performance center at a Barrett Jackson event and they said GM will probably not do anything about it. In other words, even if GM replaces the heads for free, the new heads will most likely be mis-machined, as well. I still have much of my PT warranty left. I'm really hoping GM eventually corrects this, otherwise, I may have to get rid of my Z06. Which I'd REALLY hate to do. And links of your article are being pasted all over the site and scaring the pooh out of everyone who owns one of these cars. I also suspect the crate long block engines people bought for their custom hot rods and the 427 Camaros are probably involved as well. Letting Linamar inspect their own heads and GM not doing this, which is what I surmise is what's happening from what I was told by the insider, is, to me, just a nightmare waiting to happen for their customers.

I received delivery of mine in Sept of 2012 for the 2013 model year. I have 26K+ miles now. I'm going to be watching my oil level like a hawk and developing a 'ear' for my engine. I have to take it in for the low beam headlight recall and get the brake fluid swapped out. It'll be a good time to get the wiggle test done, too. I might cost me a extra $200 or so to do this test, but, I want to nip this problem before my engine makes a window on the side of the block.

 

[C5NGAGE]

sample your oil religiously

The detection of titanium in my Z06 engine saved my engine. TES IT Needed NEW Heads AND Valves BUT It Did NOT BLoW up. And I have my old heads for rebuild if this condition reappears. Get your oil sampled.