1toofastlt1

iTrader: (4)

Hey all,
I just picked up a 02 zo6 with a 440ci ls2 long sleeve with ls7 heads. The engine has about 8k miles on it (I have receipts showing the miles). I noticed when I down shift a bunch of blue smoke comes out of the exhaust. I ran a compression test on it and i have 250-278psi. Do you think I could have bad rings? or could it be the funk PVC system they had hooked up? what should I check before I tear this engine down? The engine runs strong and the dyno sheets show 570rwhp but it smoke under vacuum conditions
Thanks

topfig1

iTrader: (5)

Valve seals? I would do a leak down test to ensure all is well with the heads. I had a 383 do the same thing a while back. I was crushed thinking it needed nother rebuild. Turned out the heads were the issue and no big deal. Good luck with it.


TopFig

LS6427

iTrader: (2)

Remove the vacuum line to the intake, cap it off and go for a drive. See if it still smokes. If it doesn't, you might just need a new $2.00 PCV valve, it could be stuck open.

If it still smokes when you go WOT from about a 60mph steady cruise speed, and you stay on the throttle and then the smoke slowly goes away as you CONTINUE accelerating....its bad valve seals.

I would say its NOT bad rings....because then you would smoke all the time under acceleration. The smoke trail wouldn't clear up as you accelerated.

I had bad valve seals and had the smoke trail when I went WOT, but then it would clear up in 2-3 seconds as I nstayed on it. Took the heads off had them rebuilt.....1-00% smoke free after that and my oil burn completely stopped. If it is bad valve seals...get ready to possibly have to clean some pistons. Look at mine below.........

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fuel

iTrader: (13)

cant you change seals with the heads on....i think you can.

2002gt

iTrader: (14)

I have the same problem. My 440 CU stroker is smoking also. Did you guys have rough idle and the smoking problem. Hopefully I don`t have bad rings.

LS6427

iTrader: (2)

Mine didn't have idle problems when my valve seals went bad. The oil will only make it by the bad valve seals when you accelerate from a steady rpm. When you push the throttle down more it creates a low pressure in the cylinders and for that few seconds till it equalizes....that suction pulls oil through the bad seals from under the valve covers.

I guess if its a really bad leaky seal allot of oil could get sucked into one cylinder or more than one, causing a rough idle.

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2002gt

iTrader: (14)

I guess I will do a leakdown check first, then start to teardown the engine. I will make sure to get the heads checked first. Hopefully it is something simple.

SlickVert

iTrader: (5)

check the rocker arm bolts.
Most ported or after market heads have the rocker arm both threaded directly into the intake port. Remove the bolts, clean with a degreaser and put some sealant on the treads and reinstall.

common problem

gtomama

True that...

1toofastlt1

iTrader: (4)

I checked all the above and replaced all my valve seals. Could it be that this motor was build with no2 in mind. My rings are gaped to .043. Could that cause blow by?

MotoFreak

man them LS7 impress the hell out of me. still best flowing heads