High iron content after new heads LS7

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erick_e

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I recently had my cylinder heads replaced under warranty. Even though the dealer changed the oil at same time, I switched to M1 0W/40 about 100 miles after the swap so I could install an E-Force supercharger.

For the past few months I have been getting a lean condition at idle. Any chance the high iron content is related?

xszj.jpg
 
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Are the cylinder heads iron or aluminum?

If you have not changed the oil, I would do so again in case were seeing manufacturing particles in the oil.
 
Originally Posted By: MolaKule
Are the cylinder heads iron or aluminum?

If you have not changed the oil, I would do so again in case were seeing manufacturing particles in the oil.


LS7 heads are aluminum as is the block. The only thing unusual about the whole engine besides the dret sump oiling system are the titanium conrods.
 
If you just replaced your LS7, and I am going to assume this is on a Z06, and they are basically the OEM cylinder heads, then the iron is probably from the valve guides if they used GM valve guides, which are a sintered iron guide.
 
Yes, OEM heads with PM sintered guides were installed under warranty.

My old guides were way out of spec (you didn't need a micrometer to see how bad they were) and iron content never showed up in previous samples.

I just don't see how guide wear would show up in a oil sample. I would think most guide material just be expended through the exhaust.
 
Originally Posted By: erick_e
Yes, OEM heads with PM sintered guides were installed under warranty.

My old guides were way out of spec (you didn't need a micrometer to see how bad they were) and iron content never showed up in previous samples.

I just don't see how guide wear would show up in a oil sample. I would think most guide material just be expended through the exhaust.


There is some slight amount of oil that could enter the oil stream. Even though there is an oil seal, I could see some working it's way in. And iron could enter through the intake side also.

Sorry to hear about your heads and hope you caught it before warranty ended. I had an 08 and one of the reasons, not the primary reason, I sold it was because of the valve guide issue.
 
Originally Posted By: Merkava_4
Why were the original heads replaced?


Heads were replaced due to noise caused by excessive valve guide clearance.
 
I don't think that a lean condition at idle could cause that much iron in 4850 miles. How much have you been romping on it over the last oil change interval? A lean condition at high power would be more likely to cause problems.
 
Originally Posted By: erick_e
Heads were replaced due to noise caused by excessive valve guide clearance.


If that's the case, with all that iron in the UOA, you may be well on your way to another set of heads. Good thing it's under warranty.
 
Originally Posted By: A_Harman
I don't think that a lean condition at idle could cause that much iron in 4850 miles. How much have you been romping on it over the last oil change interval? A lean condition at high power would be more likely to cause problems.


I haven't been on it too much, as I've been trying to figure out the lean condition.

Originally Posted By: Merkava_4
Originally Posted By: erick_e
Heads were replaced due to noise caused by excessive valve guide clearance.


If that's the case, with all that iron in the UOA, you may be well on your way to another set of heads. Good thing it's under warranty.


Unfortunately it no longer covered under warranty since the E-Force installation.
 
How many miles on the engine? I've always understood that when you get a valve job or recondition heads or brand new heads for that matter, on an old or higher mileage engine because of the increase in compression compared to the older heads you may see increased wear from the crank. Plus a supercharger is also going to increase compression and therefore pressure on the crank. Could the lean mix be a result of the mods you've done i.e.. the supercharger, and everything not being dialed in yet? Even though the supercharger isn't spooling up at idle it would seem to me that there would be an increase of air being put into the engine compared to natural aspiration. JMHO Good luck with you vehicle.

Eric
 
Hopefully, it is TOTALLY tuned for, and dialed in with the Edelbrock blower sitting on top, with NO lean conditions currently.
21.gif


Do the brand new valve guides normally slough off some iron just like the brand new main bearings give up some bronze(?) in LSx apps??
 
Originally Posted By: Merkava_4
Are you getting the same kind of noise now that you had with the previous set of heads?


There is no difference in the amount of noise.

Originally Posted By: k9jadon
How many miles on the engine? I've always understood that when you get a valve job or recondition heads or brand new heads for that matter, on an old or higher mileage engine because of the increase in compression compared to the older heads you may see increased wear from the crank. Plus a supercharger is also going to increase compression and therefore pressure on the crank. Could the lean mix be a result of the mods you've done i.e.. the supercharger, and everything not being dialed in yet? Even though the supercharger isn't spooling up at idle it would seem to me that there would be an increase of air being put into the engine compared to natural aspiration. JMHO Good luck with you vehicle.

Eric


The supercharger is the only performance mod. I'm using Edelbrock's factory tune.

I wonder if something mechanically is causing my lean issue at idle, and the high iron is just the first indicator.

Originally Posted By: dailydriver
Hopefully, it is TOTALLY tuned for, and dialed in with the Edelbrock blower sitting on top, with NO lean conditions currently.
21.gif


Do the brand new valve guides normally slough off some iron just like the brand new main bearings give up some bronze(?) in LSx apps??


It still has a tendency to run lean during extended idle.
 
How are you monitoring the lean condition?
Is it using wideband O2 sensors?

And on a separate note:
Does the Edelbrock E-force supercharger have a bypass valve?
 
Originally Posted By: A_Harman
How are you monitoring the lean condition?
Is it using wideband O2 sensors?

And on a separate note:
Does the Edelbrock E-force supercharger have a bypass valve?


After it started setting the CEL, I started monitoring it using a Tech 2, and data logging using SCT Live Link software.

Yes, the E-Force has a internal bypass valve.
 
Wow... I'd be ringing some heads at GM for what you paid for that car/engine!!

Just one more reason I hate the LS motors... and GM in general anymore... so many problems with them over the years. Sure they're fast WHEN they run but I know of many friends over the years with 40-50k miles replacing engines, heads etc.

One thing I'll give my fords, might be underpowered but a 4.6/5.4 mod motor will run forever and take anything you can throw at it! Add in the ol 302/5.0 and even the 300 straight 6 motors. Bulletproof! Sorry... did I mention I was a blue oval guy?
 
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