VeTTeMaNC486

Hello,

First off, the car is a 2004 z06 with full bolt ons and a TSP tsunami cam. Ever since I got the car it has gone through about a quart of oil per change, as have all other ls power vehicles I have had, so that didnt concern me. Lately I have noticed my car smoking at idle when its hot. When I crank it after it sits it would give a small puff of smoke (very small... not as bad as my c4 did that had bad seals) and it would go away after like 1.5-2secs and not smoke anymore until it warmed up, at which point it would begin to smoke at idle. It will also give a nice blue smoke trail under wot from 6k-7k rpm (rev limiter is bumped up to 7k), but only during that rpm range. If i go wot and shift at say 5.5k or lower it doesnt smoke. Also, this past oil change it used 2 quarts in around 3500 - 3600 miles.

I am leaning more towards rings, but am holding out hopes it can be valve seals/guides. I have heard that cams over .600 lift can cause guide wear if using stock rockers, my intake lift is .647 and the cam has been in the car for probably 20k miles. (has like 55k on it now)

Opinions?

VinnyT

Sounds like rings. Pull a few plugs and see how they look.

jcgunn

Smoking after start only is usually valve seals. Smoking under load is usually rings.

racebum

this

and valve guides having excessive clearance is usually what kills seals

the smoke trail under WOT would have me suspecting rings

sounds like a worn motor all around really. if you run these cars hard the engines are only good for 150-200 hours of track time. regardless of what the odo says if the car has a good deal of race mileage it may be in need of a rebuild

slocobra

any blowby when you take off oil fill cap while at idle? If so I would say worn motor, if not Id start looking at valve stem seals and valve guides.

Just did my seals they were all destroyed. only difference is it used a TON of oil. like a qt every 1K miles..lol

racebum

the oil cap test and a manifold vacuum test will let you know if there is compression loss

a manifold vacuum gauge will flutter if one cylinder is low/high compared to the others. normally with worn engines there's always that one cylinder that's REALLY bad

VeTTeMaNC486

I took the plugs out, did not have any oil on any of them. Not sure what I'm looking for. I snapped some pics, but it was with my phone, so they look muuuch darker than they really are. Let it run until it was smoking pretty good at idle, took the oil fill cap off, and there was nothing coming out. Same goes for the dip stick. I'll post pics later this evening.

racebum

with the oil cap off did you put your hand over it and feel for pressure blowing into your hand?

VeTTeMaNC486

I did, and I did not feel any pressure on my hand. There is some oil in the intake behind the throttle blade, but not really anymore than last time I had the throttle body off (was not having any issues at that time).

And the only racing it has done is 1/8th mile dragstrip passes (with maybe 10 or so 1/4 mile passes) mostly back when it was bolt on only. I would estimate 50 or so passes total. I really don't drive the car that hard. I might go through 1st and 2nd maybe 3rd once a week. I am having clutch troubles and a sticky clutch pedal kind of takes the fun out of rowin' the gears .

Here are the pics of the plugs. They did not look near this dark in person mind you..



This is another pic of the darkest plug, just trying to get better light on it.



As I said, there was no oil or wetness at all on any of the plugs, also it drives fine and as smooth as it can be (other than a little cam surge at like 45mph in 6th..)

slocobra

At this point I would take a good look at the guides and valve stem seals. do You have a catchcan? is your PVC system working correctly, no stuck valve or pinched lines?

racebum

plugs look fine

if you're racing and only going through a quart every 3000 that's pretty good. you will suck some in the pcv system under high rpm use

when we say the 02+ cars don't burn oil that means in normal driving.

any car subject to high rpm driving burns oil to some degree

during the summer when i went to the strip a few times and did time trials i went through...maybe 1/2 a quart on that change and my car doesn't smoke at all, inside the intake and pcv had a nice oil film on them though

VeTTeMaNC486

No catch can yet, it is on my list of things I need to purchase/do (long list ). How do I verify if it the PCV system is working correctly? I do not know if the valve is stuck, how can I tell? I'm fairly certain there are no pinched lines, but I will check. Is there a way to check the valve guides with the heads still on it? I assume not, but this is my daily driver so I really need to keep down time to a minimum.

The thing is, I am not racing it. It only sees high rpms like once a week, which is slightly less than once per fill up (116 miles a day to and from work...) It is usually just in 6th gear putting along at 65-70mph. Honestly, it isnt the consumption that bothers me, its the mosquito fogging that its doing.

I have a friend who has a ls1 trans am that used to drink oil like it was gasoline, and he switched to thick dino oil and he said it really helped with the consumption. To me that just seems like a band aid instead of a true fix....

racebum

the engine isn't burning enough oil to tell. i had a honda vtec engine that drank a quart every 2k miles and it also did the puff of smoke above 6000 to 8500 and continued to do for for another 60k miles before it started getting worse and eventually fragged a valve. the plugs looked nothing like yours and there was oil residue on them

if you want to seriously troubleshoot this i would

1. do a cylinder leakdown test
2. check manifold vacuum and look for any flutter
3. replace the pcv valve

the leakdown and vacuum test will tell you if there are any internal issues

the other thing with high rpm puffs, how much of it is gas? is the car tuned rich at WOT?

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sami85L98

Very good advises from everyone so far, being a mechanic myself although i am general repair guy on all makes and models (well most) but have worked on LS motors too few times including new Re-rings on my 01 LS6 and lot more.

Do small things first upper end, leak down test, air escaping from oil fill cap definitely rings, however you can go ahead replace valve seals first...see how it goes and if you still get smoke puff in morning or cold engine...if no than if still smoke at WOT than Rings for sure....at this point Re-ring or rebuilt short block in order, Valve seals and guides wont wasted as you can re-use those heads back again on same rebuilt motor.

Another opinion besides awesome posts above.

slocobra

If your pvc system looks good, Im putting my money on the valve seals and guides, and if its not, as stated above at least its not wasted time and money.

GO_BLUE_VETTES

What was the ultimate conclusion / solution? VeTTeMaNC486?

I am facing a somewhat similar problem with my '01 LS6

RedZMonte

01 Z's had an oil consumption issue. there is a TSB about it, i know the dealers were replacing the rings under warranty.. but a little smoke/oil consumption is normal for many 01Z'2

GO_BLUE_VETTES

Unfortunately, it's not as simple as the issue in that TSB. I am working to diagnose if it is a broken ring or bad intake valve. Leakdown test suggested the intake valve, but it took the heads to a shop and they checked out ok.