meridock

Let preface this as I am a 3 year owner of a 2010 Z. I bought it used as certified preownerd with 5k miles on the clock. I have had the car in for oil consumption I documented in 2016 here under:

https://www.corvetteforum.com/forums...nsumption.html

Staring 2 weeks ago I noticed a weird thing on a cold start that I decided to document: Oil in the exhaust on cold start. Blue Exhaust of Death if you were...

4 hours in cold

8 hours in cold

(color is not steam color)

(this last one is most concerning and notice the two soot marks on floor.)

So I decided to take it to the dealership for another round since the car is under warranty and this is a new thing. My thought was valve guides leaking down over night into the heads. I had to leave it there for the Corvette dude to review and diagnose with help from Corvette engineering. I presented the videos to my service agent to show it is not my imagination and such and the car is literally puffing oil out the exhaust on cold starts. He reviewed the videos with me and confirmed he saw what I saw. I also asked for his technician to take a buddy to start the car so he can observe it himself.

My call today from the advisor was in his words "not looking so good." so I am thinking that this means pop the heads and replace. Actually, what he meant was the engineer at GM is leaning at blaming the oil consumption on "how these cars get driven."

Couple things to note.

• This car has less than 37k total miles on it.
• I daily drive it in all weather done to 40 degrees on wet days and into the 20's on dry days.
• My commute is along I66 to herndon VA with its.notorious bad traffic.
• I do not track the car at all
• Religious tracking of oil consumption
• No smoke puff in the previous 2 years of cold weather

So let me get this straight - It seems no matter how hard I actually drive the car GM will say something to the effect of these cars will consume oll if driven anywhere over 3k RPM, and will BURN oil in 37k miles?

We left the call with it is not final yet, but I think I will be getting a call to say "normal" operation. Does anyone have advice on escalation on this type of thing? I have 3k miles and 2 months on the warranty, and am not exactly wanting to replace the heads under my dime, fund GM to pop heads and check valves myself to "prove" a mechanical issue, or anythign like that. I just want a proper diagnosis cause in any car under warranty this is not normal operation, or acceptable.

Thoughts?

S.

meridock

FOr some reason the last video is not showing ...

Texasthunder

I would say valve guides for sure. If they don't want to fix it under warranty I would take it to a certified GM shop and get a wiggle test done. They know the guides are crap on these cars. Don't take NO for an answer.

meridock

I thought the wiggle test was no longer accepted as proof that the heads were faulty? Meaning if we are both right I am still on the hook for diagnostic and would still need to fight GM. But you are correct - no way this is normal function of the LS7. Especially with the soot lines from the exhaust. that are very recent - if you look at the video from the 16 and compared to the 21st the soot lines are there from 3 cold starts in between videos.

Too-Fast

rjacobs

looks like condensation to me. And the black soot drops from the exhaust are carbon and water(condensation). Looks pretty normal to me. I also dont see the blue hue to the exhaust.

And the LS7 has a pretty common issue with pushing oil into the intake manifold...especially if driven at high RPM... get a catch can...

meridock

There is a blue hue in the exhaust, and the condensation appears only after the pipes warm a slight bit.

@too fast - I understand the comment but in a time where I am actually babying the cars as November to March-ish there is no hard launch to sky high revs it is high odd to start seeing this puff off smoke this month after not even pushing the car for months. the car has never smoked or smelled bad even when the GM eng team said normal consumption in 1-2+ quarts per 5k miles of driving (!).the last video had the audible of my 13 year daughter saying it "stank" again this past 2 weeks have changed the view of the car.


Smoking and Stinking on start up are not the normal operations of a daily driven car. it Does remind me of my dad's 78 Malibu. 2 rebuilds in and it still burns oil like a WWI battleship.

Apocolipse

Takes 10 min to pop a valve cover off and wiggle a few around. If there is an issue on 1 or 2 of em it will be obvious.

Landru

Somehow oil's getting into where it shouldn't be, burning-off at startup.
Might be bad seals allowing slight amounts of oil past into cylinder(s)?

OTOH if it is guides going south, it's a rare instance of a warning.
Moreover if GM's bucking responsibility insofar as at least looking for a cause it's up to you to be proactive.
Have heads thoroughly inspected by a pro...and not one from a GM dealership.
Find a solid indy HP shop w/ references who're familiar w/ LS7.
Tell 'em what's happening & look specifically for bad guides/seals.

If you love your LS7 as I & many other owners do the goal is keeping it alive, in your case in spite of GM.
GM would love selling a new LS7, after warranty runs out.
Low rent way of doing business, granted; but, bottom line's ball's in your court.
G/L, post follow-ups please.

meridock

Yep - kinda my thought. GM seems to be hiding behind "its how this car (or these cars) are driven" comment that is a bit infuriating. Cars don't smoke with 37k miles. Especially cars that are commuting 90% of the time, with the remaining 10% taking girls to softball practice and general weekend chores.


I totally understand I use the Z06 in a non-typical way, but I really love the look compared to my 2006 Base model. Still wishing I had found a Grandsport in 2015 when I decided to change cars. the LS3 is rock solid.

MTPZ06

If you're looking for precise measurements, there's better (more invasive tests)...but the wiggle test is a very good indicator of whether or not you have a problem that requires a closer look.

^ This

Dirty Howie

OP get the wiggle test done by someone that can confirm valves guides are worn beyond spec. Then take it to your dealer and agree to pay the inpection fee if they are in spec which is extremely unlikely. If they are out then you get charged nothing and will get a new set of heads. I just went through this a few months ago and I had aftermarket warranty through Vehicle1


DH

Gary '09 C6

449er

Dirty Howie has a good suggestion, have the dealer perform the valve guide inspection test, depending on what they find, they are on the hook for the fix if the guides are out of spec. You don't want to grenade one of these engines

meridock

I talk to Tony from Tony's Corvette tomorrow to see what are my options - he is an authorized service center for GMPP extended warranties in addition to the speed shop that did my header install on my last vette.

The update from the dealership is no update as of COB today. They will try again with Corvette engineering on Monday. (i am not holding my breath...)

meanjoe

With your mileage, I'm going to figure that you have a 90% chance of having out of spec valve guides. Valves will wiggle even with the springs on in a bad guide. I know this as that's how I found mine bad at only about 3500 miles. Spend the 45 minutes it takes to remove one of the valve covers and see what you find.
Good luck with the dealer.

farmington

Jfryjfry

meridock

I haven't looked there yet.


I did think about doing a few redline pulls since I haven't done many of those in the car.

Millenium Z06

Looks like valve stem seals to me but it's definitely oil leaking into the cylinder during periods of none use.
I'd pull the TB off and look down the intake and see if there's any oil in it otherwise, put an air line in the cylinder and pull some strings and see how the valve guides feel and how the seals look