Is this piston ring flutter? Correct answer wins money
05-01-2006, 11:15 PM
#21
Originally Posted by nytoy
Me too, motor was bone stock before the rebuild. EVAP and EGR system is gone, hmmm think that's messing things up?
BTW you say the motor was bone stock before. That does or does not include the cam. I hear some people say bone stock but have a cam in it.
05-01-2006, 11:27 PM
#22
On The Tree
Join Date: Feb 2005
Location: Odessa, TX
Posts: 178
Likes: 0
Received 0 Likes
on
0 Posts
Why did we rebuild the first time? I beleive it is in the rings. You can get oil into the top end from the rings. It occurs when the cam is in overlap, and an opposing cylinder is on the intake stroke. I tried for a month to convince myself it was not happening to my new 402. When we tore it down the cylinder that was causing the problems was out of round by .0015. I would tear back into it and hone it .005 with a plate put new pistons and try again.
05-02-2006, 08:33 AM
#23
On The Tree
Thread Starter
iTrader: (3)
Join Date: Dec 2004
Location: Rochester, NY
Posts: 169
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Boostaholic
I would try and cap off the lines that run from valve cover to throttle body/intake area and then test drive the car, that might lead you to your answer
05-02-2006, 08:41 AM
#24
On The Tree
Thread Starter
iTrader: (3)
Join Date: Dec 2004
Location: Rochester, NY
Posts: 169
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by kossuth
Not a chance. Here is another question and this might be a different approach to it. Is the oil getting burnt in the combustion chamber? I ask this question because it might getting burnt in the exhaust off the hot headers. Think of it like this. The cylinder ignites, and starts the piston down on the power stroke. Piston expands alittle, and pushes the rings out against the cylinder wall opening the gaps up alittle. Maybe letting oil by as it is scrapping on the way down. Piston reaches BDC and begins it's travel upward with the exhaust valve open. Now the rings are laying against the bores on their own tension scraping oil off the walls as it goes pushing it in a somewhat atomized state out the exhaust valve and onto the hot headers. Did you have the same cam in the motor before you had it rebuilt? Also what did your engine builder spec the ring gaps at? Stock pistons or aftermarket? I doubt any of that is amiss. It might be something to do with cylinder pressures vs valve events. Have you ever checked to see what kind of crankcase pressures you are seeing on the motor? Another stupid question LS1 or LS6 block? Might also have to do with bay to bay breathing in combination with the cam.? It's hard to put a finger on it without seeing it. If you had a stock cam laying around I would almost be willing to throw that in the motor and see what it does. The only factors that remain consistant with the oil burning is the block itself and the cam everything else has been redone correct? If you were feeling frisky I guess you could swap the cam and see if it changed anything. I doubt it would change anything but then again what haven't tried yet? I'm outta ideas.
BTW you say the motor was bone stock before. That does or does not include the cam. I hear some people say bone stock but have a cam in it.
BTW you say the motor was bone stock before. That does or does not include the cam. I hear some people say bone stock but have a cam in it.
It burns oil when I'm off the gas at high rpms and under power, but I believe it's just leftover oil in the chamber because it will go away under WOT after a minute, so this leads me to believe that only under the super high vacume situation of high rpms in gear is oil getting pulled into the chamber somehow.
Can I pull the spark plugs and see if they are oily, would that tell me anything?
I peaked into the intake last night and couldn't really tell if it was covered in oil or not, I'll pull it totally off tonight.
LS6 cam before the rebuild, 224/224/114 TR cam after the rebuild, stock everything otherwise.
Correct, I reused the intake (is it possible this is cracked were I can't see it) The heads, I doubt there's a crack in them. And the block, I almost was thinking there is a hairline crack somewhere and it's pulling from there, but who knows.
My only next thought is swapping the heads and intake, and if it's the same, that that narrows it down to the shortblock correct??
Again thanks for all the good info!
05-02-2006, 08:43 AM
#25
On The Tree
Thread Starter
iTrader: (3)
Join Date: Dec 2004
Location: Rochester, NY
Posts: 169
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by MAC4264
Why did we rebuild the first time? I beleive it is in the rings. You can get oil into the top end from the rings. It occurs when the cam is in overlap, and an opposing cylinder is on the intake stroke. I tried for a month to convince myself it was not happening to my new 402. When we tore it down the cylinder that was causing the problems was out of round by .0015. I would tear back into it and hone it .005 with a plate put new pistons and try again.
AH! Very interesting, I was thinking the same thing about getting oil into the top end, thinking there's no way it could be the rings!
Hmmm that sounds like my last option, I'm using stock pistons. I'm wondering if it would even be worth to change out the heads and intake manifold just for testing purposes.
Last edited by nytoy; 05-02-2006 at 08:50 AM.
05-04-2006, 10:20 AM
#29
TECH Regular
Join Date: Jul 2004
Posts: 419
Likes: 0
Received 0 Likes
on
0 Posts
seal those rocker arm bolts/holes
and then I'd think about an out of round cylinder or a bad oil controll ring installation
I think its the unsealed rocker arm bolt holes because that would leak only under the extreme vacuum during lift-off and show its smoke cloud upon re-acceleration.
oil control rings would be a similar situation, leaking at off throttle and then showing smoke at on-throttle... like my GSR motor did and it was indeed the oil control rings being pinched in the piston groove, so tightly pinched in place that they didnt expand to scrape the oil off the walls. (DOH!)
and then I'd think about an out of round cylinder or a bad oil controll ring installation
I think its the unsealed rocker arm bolt holes because that would leak only under the extreme vacuum during lift-off and show its smoke cloud upon re-acceleration.
oil control rings would be a similar situation, leaking at off throttle and then showing smoke at on-throttle... like my GSR motor did and it was indeed the oil control rings being pinched in the piston groove, so tightly pinched in place that they didnt expand to scrape the oil off the walls. (DOH!)
03-03-2007, 10:24 PM
#30
12 Second Club
Join Date: Jan 2007
Location: Greenwood SC
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
I have the exact same problem...mine didn't start until I change exhaust...I went with mac shorties and no cats...been smoking ever since...but only when I get above 3k rpm gives a good cloud then goes away and then if I leave it in gear it will puff again on the decel...
03-04-2007, 12:02 AM
#32
TECH Junkie
iTrader: (3)
Join Date: Nov 2001
Location: TEXASS
Posts: 3,202
Likes: 0
Received 0 Likes
on
0 Posts
Id pull the plugs and see if you can tell which cylinders are burning oil. If its all of them the problem is not the shortblock. If just one, two or three etc its probably out of round cylinders.
