Smoke after idle...
05-10-2012, 12:36 PM
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Smoke after idle... I can't find a definite answer searching, but if I missed something, feel free to point me to the thread.
Lately I've noticed that if I let my car (2000 LS1 M6, stock motor) sit at idle for some time (10-20 minutes), and then quickly rev it a bit (quickly go from idle to 2,500-3,000 rpm), it'll give a decent puff of white/slightly blue smoke. Rarely, when I restart after it's only been off for a short time, I'll hear a slight knock (just once) and get a similar puff of smoke. It always starts quickly and easily. The smoke smells like oil. It doesn't smoke just sitting at idle, nor at any other time, just after revving it after it's been at idle a while. It uses maybe a half a quart every 3,000 miles, and has since I got it. From what I've read, it sounds like it may be valve seals. Would this be a correct assumption? What else should I check?
Lately I've noticed that if I let my car (2000 LS1 M6, stock motor) sit at idle for some time (10-20 minutes), and then quickly rev it a bit (quickly go from idle to 2,500-3,000 rpm), it'll give a decent puff of white/slightly blue smoke. Rarely, when I restart after it's only been off for a short time, I'll hear a slight knock (just once) and get a similar puff of smoke. It always starts quickly and easily. The smoke smells like oil. It doesn't smoke just sitting at idle, nor at any other time, just after revving it after it's been at idle a while. It uses maybe a half a quart every 3,000 miles, and has since I got it. From what I've read, it sounds like it may be valve seals. Would this be a correct assumption? What else should I check?
05-10-2012, 02:07 PM
#3
Certainly oil from the color. Either through the seals or rings but some is getting by and your getting a slight build up and as soon as you "clean off" the combustion chamber and valves thats when it gets combusted.
On a off chance it could be OIL though the intake but I would pop off the T/B and feel around. Probably will have some residue but maybe not enough to do what its doing.
On a off chance it could be OIL though the intake but I would pop off the T/B and feel around. Probably will have some residue but maybe not enough to do what its doing.
05-10-2012, 08:22 PM
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Thanks guys! How can I tell if its the rings or valves? Compression test? How difficult is it to change valve seals? I'm guessing you must pull the head?
I don't know if it means anything, but every now and then, the oil pressure gauge will flutter. Never more than a few PSI variance, but it'll just vibrate slightly while at idle, and rarely while driving at low RPM. With revs of 1300 or more, the fluttering stops. I usually see 45 PSI cruising at 1100 RPM's, 70-75 under a hard acceleration, and usually 40 at idle. Sometimes it'll be just below 40 at idle, not sure what causes the variance.
I don't know if it means anything, but every now and then, the oil pressure gauge will flutter. Never more than a few PSI variance, but it'll just vibrate slightly while at idle, and rarely while driving at low RPM. With revs of 1300 or more, the fluttering stops. I usually see 45 PSI cruising at 1100 RPM's, 70-75 under a hard acceleration, and usually 40 at idle. Sometimes it'll be just below 40 at idle, not sure what causes the variance.
05-10-2012, 08:27 PM
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Well for the rings at least take it to a shop or dealership and have them perform a leakdown test. I cant remember if it is good for valves. But if theres a valve seat problem you probably have a vacuum. Problem as well so that would be another test to run
05-10-2012, 08:50 PM
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Will do. I can monitor vacuum in real time as I drive, using the MAP sensor I assume. Is that an accurate reference? Is there a specific number I'm looking for?
