docwyte

iTrader: (4)

'02 LS1 75k ish miles
Road course track motor for the past 3 years.
EPS cam, pushrods, double roller timing chain, FAST90/90, 1 3/4" long tubes.

I've been burning oil and smoking on decel. Did a leakdown and compression test and they were both good, so I replaced the valve stem seals.

Not smoking as much, but still noticeable on decel and still burning oil.

I noticed some play in the exhaust valve guides while replacing the valve stem seals.

Could that be causing all of this? Should I do another leakdown/compression test?

Last thing I want to do is buy and install a new set of ported 243's only to find my bottom end is bad and I should've spent the money on a crate LS3 motor...

C5_Mike

The bottom end is pretty stout so I would be surprised if that was the issue.


My first guess is Valve seals due to the fact that it's on decel like you said. But you already did that. Do you have a catch can? I am guessing you rev your car out pretty high being a road coarse car. A catch can can be a big benefit for that type of driving.

Z28SteveA4

iTrader: (16)

it still can be getting pushed past your rings on decal. I would put a catch can on if you don't have one already and check to see if you have oil in you intake.

docwyte

iTrader: (4)

I've got an ls6 valley cover plumbed into an elite engineering catch can. Not much ending up in the catch can...

td1168

iTrader: (2)

If you leak tested the engine and all cylinders checked good why would you still think it's your bottom end? Its either the guides or pcv. If you have excessive guide clearance new seals would slow it down but won't completely fix the problem.

docwyte

iTrader: (4)

Mostly fear I suppose. The reason why I have the LS1 in the car now is the factory Porsche motor failed. It was blowing blue smoke on decel and it took some time and several leak down tests before it finally showed up as a bad cylinder.

I'm reluctant to put money into the heads unless I'm sure the smoke on decel can be attributed to the worn exhaust valve guides...

moosifer

iTrader: (1)

Did you do a wet compression test as well? That test will tell you for sure if your rings are sealing or not. No jump in compression means the rings are sealing. Jump in compression means the rings are leaking.

ws6guy27

iTrader: (31)

I would almost bet its a set of your rings in one or more cylinders. Either bad rings or stuck rings. Iv been in this same boat. Had tear down motor fix the waffle ring btwn the 2 oil control rings and put back together. Gained power back and smoking quit

docwyte

iTrader: (4)

ws6guy27, you didn't have any cylinder wall or piston damage? You just had to replace the rings?

moosifer, no, just did a dry compression test, but that's a great idea. I'll do a wet compression test after the last event of the season at the end of this month.

Question is if it's cheaper to tear this motor down and fix the rings vs getting a crate LS3...

docwyte

iTrader: (4)

Just did a wet and dry compression test. Numbers were good (for my altitude) and didn't change when oil was squirted into the chambers.

Car is smoking at start up and on decel. Quite a bit actually. So where to go from here? Is it possible that the oil control rings are bad, but the compression rings are good? All coming from worn valve guides in the heads?